[YamahaDX] Early TX816 capacitors [2 Attachments]

[[e-mail] [YamahaDX]]

Hi,

I just sold locally my DX7 along with its DX MAX 3 card (along with a Sony BVM monitor) to get the beast that's the TX816 (well actually a TX516 since it has 5 TF1s).
I was told it's a day one model, the previous owner bought it directly from a Yamaha dealer in Japan the day the first units came out of the factory (SN# 1010, is there anyone here who like to share its TX SN too? the TF1's SN# are also in the 4 digits range).

Well that was the story about this particular unit. Now it's working (I tested it at the seller's) but since It's 32 years old I'm dissasembling it for the obligatory maintenance before using it at home and, wow! what a surprise I got. The TF1's PCB are in a pristine condition, all the (Sanyo) lithium cells are still 3V (!) and only two capacitors per TF1 board are slightly bulged (always the same, the biggests, near the bottom left corner of the PCB), but none are leaking. Talk about a marvel of Japanese engineering!

So now I'm in the quest of changing these 5x2=10 capacitors (I know I should do them all to let them age at the same rate but I'd rather modify this machine only when I really have to in order to not hurt it).
What should I order? The original ones were Nichicon 16V 100µF @85°C. I'm tempted to take the same ones but with higher temp spec (105°C since 135°C seems a bit overkill, and more expensive) but I don't want this decision to alter any of the legendary sound quality of these early TX units. What would you recommend? Also my supplier is letting me decide between 16V DC or just 16V (I assume AC) for the capacitors, what should I choose?

I attached pics of the capacitors and the PCB in order to let you tell me if the capacitors are on the audio path (I think not, they are likely to be filtering the power supply but I'm no expert).

Another subsidiary question: does the ROM of the indiviual TF1 module has been dumped? I cannot find a reference to this. Like I said earlier I'd rather not tinker too much with the insides of the TX but if it could help someone or the community at large I'd be willing to take the chance to do it. Let me know.

Cheers in advance for your feedback,

Jonas

[Takis [e-mail] [YamahaDX]]

These are just standard general purpose caps.

Any 100uf capacitor at the rated or higher voltage and temperature will do.

I'd go with ***@25V Nichicon PW series or Panasonic FM but low esr is
not of great importance there, these are just quality cap series that I
personally keep in stock and use.

Truth is that any reputable branded cap should last forever as a
replacement if genuine and properly stored since manufacture date.

I wouldn't expect any sound difference though.

Caps that could make a difference are almost always found on analog
synths and in the voice(s) or filter(s) sections.

Decoupling capacitors or power supply filtering capacitors are there
just for eliminating power supply ripple.

below]
Hi,
I just sold locally my DX7 along with its DX MAX 3 card (along with a
Sony BVM monitor) to get the beast that's the TX816 (well actually a
TX516 since it has 5 TF1s).
I was told it's a day one model, the previous owner bought it directly
from a Yamaha dealer in Japan the day the first units came out of the
factory (SN# 1010, is there anyone here who like to share its TX SN
too? the TF1's SN# are also in the 4 digits range).
Well that was the story about this particular unit. Now it's working
(I tested it at the seller's) but since It's 32 years old I'm
dissasembling it for the obligatory maintenance before using it at
home and, wow! what a surprise I got. The TF1's PCB are in a pristine
condition, all the (Sanyo) lithium cells are still 3V (!) and only two
capacitors per TF1 board are slightly bulged (always the same, the
biggests, near the bottom left corner of the PCB), but none are
leaking. Talk about a marvel of Japanese engineering!
So now I'm in the quest of changing these 5x2=10 capacitors (I know I
should do them all to let them age at the same rate but I'd rather
modify this machine only when I really have to in order to not hurt it).
I'm tempted to take the same ones but with higher temp spec (105°C
since 135°C seems a bit overkill, and more expensive) but I don't want
this decision to alter any of the legendary sound quality of these
early TX units. What would you recommend? Also my supplier is letting
me decide between 16V DC or just 16V (I assume AC) for the capacitors,
what should I choose?
I attached pics of the capacitors and the PCB in order to let you tell
me if the capacitors are on the audio path (I think not, they are
likely to be filtering the power supply but I'm no expert).
Another subsidiary question: does the ROM of the indiviual TF1 module
has been dumped? I cannot find a reference to this. Like I said
earlier I'd rather not tinker too much with the insides of the TX but
if it could help someone or the community at large I'd be willing to
take the chance to do it. Let me know.
Cheers in advance for your feedback,
Jonas

[Takis [e-mail] [YamahaDX]]

I just looked at the attached pictures and if I'm not mistaken those
caps seem to be bipolar.

I see BP marked on the side and no strip indicating negative polarity
but I'm not 100% sure.

If that's the case, you should use bipolar caps.Most of them are suited
for audio applications too.

Post by Takis ***@yahoo.com [YamahaDX]
These are just standard general purpose caps.
Any 100uf capacitor at the rated or higher voltage and temperature will do.
is not of great importance there, these are just quality cap series
that I personally keep in stock and use.
Truth is that any reputable branded cap should last forever as a
replacement if genuine and properly stored since manufacture date.
I wouldn't expect any sound difference though.
Caps that could make a difference are almost always found on analog
synths and in the voice(s) or filter(s) sections.
Decoupling capacitors or power supply filtering capacitors are there
just for eliminating power supply ripple.

Post by ***@yahoo.fr [YamahaDX]
Hi,
I just sold locally my DX7 along with its DX MAX 3 card (along with a
Sony BVM monitor) to get the beast that's the TX816 (well actually a
TX516 since it has 5 TF1s).
I was told it's a day one model, the previous owner bought it
directly from a Yamaha dealer in Japan the day the first units came
out of the factory (SN# 1010, is there anyone here who like to share
its TX SN too? the TF1's SN# are also in the 4 digits range).
Well that was the story about this particular unit. Now it's working
(I tested it at the seller's) but since It's 32 years old I'm
dissasembling it for the obligatory maintenance before using it at
home and, wow! what a surprise I got. The TF1's PCB are in a pristine
condition, all the (Sanyo) lithium cells are still 3V (!) and only
two capacitors per TF1 board are slightly bulged (always the same,
the biggests, near the bottom left corner of the PCB), but none are
leaking. Talk about a marvel of Japanese engineering!
So now I'm in the quest of changing these 5x2=10 capacitors (I know I
should do them all to let them age at the same rate but I'd rather
modify this machine only when I really have to in order to not hurt it).
I'm tempted to take the same ones but with higher temp spec (105°C
since 135°C seems a bit overkill, and more expensive) but I don't
want this decision to alter any of the legendary sound quality of
these early TX units. What would you recommend? Also my supplier is
letting me decide between 16V DC or just 16V (I assume AC) for the
capacitors, what should I choose?
I attached pics of the capacitors and the PCB in order to let you
tell me if the capacitors are on the audio path (I think not, they
are likely to be filtering the power supply but I'm no expert).
Another subsidiary question: does the ROM of the indiviual TF1 module
has been dumped? I cannot find a reference to this. Like I said
earlier I'd rather not tinker too much with the insides of the TX but
if it could help someone or the community at large I'd be willing to
take the chance to do it. Let me know.
Cheers in advance for your feedback,
Jonas

[[e-mail] [YamahaDX]]

Yep, they look like bipolar to me. No stripe and what looks like a BP marking.

[[e-mail] [YamahaDX]]

Well spotted. I missed that. They may well be bipolar.

Are there just two? Maybe they are for the headphones socket.

What looks like a marking for the negative lead isn't - it's the manufacturers name.

But, yes, electrolytic capacitors do wear out. It's one of the main reasons old equipment dies. If you look at datasheets or suppliers listings, you'll normally see an alarmingly short lifespan, rated in thousands of hours - and often only one or two thousand.

Andy

[Takis [e-mail] [YamahaDX]]

You may as well know that, but the service hours are stating capacitor
lifespan in hours worked under the rated temperature.

At 85 celsius this may or may not be alarming but for 125 rated caps
it's almost impossible for a cap inside consumer equipment to "see" that
kind of temperature.

I've yet to encounter equipment that reaches 70 or more ambient
temperature so the caps internal temp is not easy to reach even 85
celsius most of the time.

Also ,the majority of chips usually have max operating temperatures far
lower than the capacitor temp ratings so under extreme circumstances the
caps are tested for, even if the capacitor can withstand this kind of
heat the machine would probably fail anyway because of the chips not
operating correctly.

That's why it is typical to find caps thousand hours older than the 1 or
2k hours one sees in the datasheets.

Caps are temperature over-rated for most consumer applications.(all that
applies to quality caps not the chinese junk you see everywhere these days)

Post by ***@ntlworld.com [YamahaDX]
Well spotted. I missed that. They may well be bipolar.
Are there just two? Maybe they are for the headphones socket.
What looks like a marking for the negative lead isn't - it's the manufacturers name.
But, yes, electrolytic capacitors do wear out. It's one of the main
reasons old equipment dies. If you look at datasheets or suppliers
listings, you'll normally see an alarmingly short lifespan, rated in
thousands of hours - and often only one or two thousand.
Andy

[Takis [e-mail] [YamahaDX]]

Drying electrolyte on the other hand can cause internal capacitor
resistance to rise leading to higher cap temperatures under normal
operation but in that case we already have a failing or soon to fail
cap.The fact that it can withstand its "failure" makes it no less
failed.(I could've said that better, I know;))

Even if a cap is designed to last more under temperature stress,
capacitors that reach that kind of temperature marks are probably
already due to be replaced.

It's just less probable to fail in a spectacular or leaky way.I believe
that's the principal reason people use higher temp caps in consumer
stuff.They usually fail "quieter" than standard caps but that doesn't
prevent from drying.

One can argue though that higher temped caps might have better
electrolyte formulas to begin with.I'm no cap expert though, so I can't
tell for sure.

Post by Takis ***@yahoo.com [YamahaDX]
You may as well know that, but the service hours are stating capacitor
lifespan in hours worked under the rated temperature.
At 85 celsius this may or may not be alarming but for 125 rated caps
it's almost impossible for a cap inside consumer equipment to "see"
that kind of temperature.
I've yet to encounter equipment that reaches 70 or more ambient
temperature so the caps internal temp is not easy to reach even 85
celsius most of the time.
Also ,the majority of chips usually have max operating temperatures
far lower than the capacitor temp ratings so under extreme
circumstances the caps are tested for, even if the capacitor can
withstand this kind of heat the machine would probably fail anyway
because of the chips not operating correctly.
That's why it is typical to find caps thousand hours older than the 1
or 2k hours one sees in the datasheets.
Caps are temperature over-rated for most consumer applications.(all
that applies to quality caps not the chinese junk you see everywhere
these days)

Post by ***@ntlworld.com [YamahaDX]
Well spotted. I missed that. They may well be bipolar.
Are there just two? Maybe they are for the headphones socket.
What looks like a marking for the negative lead isn't - it's the manufacturers name.
But, yes, electrolytic capacitors do wear out. It's one of the main
reasons old equipment dies. If you look at datasheets or suppliers
listings, you'll normally see an alarmingly short lifespan, rated in
thousands of hours - and often only one or two thousand.
Andy

[[e-mail] [YamahaDX]]

I expect you're right about the rating, but the point is, electrolytic capacitors don't last forever, and can't reasonably be expected to.

I can think of two pieces of equipment in my life, off hand, that routinely suffer severe capacitor failure.

One is the Casio DH-100. They are notorious for just one particular capacitor failing. I bought one already failed that way (knowingly), and replaced it with a tantalum bead, which I hope will last longer.

The other is a TV recorder box, I own, which I sent to be repaired to someone who has a lot of experience of repairing that particular model - actually, he just replaces all the electrolytics in the power supply, so I didn't have to send the whole thing. I could have done it myself, but I'd far rather pay someone who's good at it, and has the experience, if the price is fair.

In both cases, they are clearly not specified to withstand the conditions they routinely encounter, and in the case of the Casio DH-100, it was just poor design - the capacitor presumably overheats, but due to too much current going through it.

In the case of the TV recorder, they probably did their best given that it's a small enclosure that generates quite a bit of heat from a RISC CPU and an IDE hard drive. Apparently, mine had lasted longer than most, and most likely, it will fail again, in few years, or a sooner.

The capacitors probably didn't reach their rated temperature, but the heat still shortened their life, because they were at a good fraction of it for long periods of time.

I'm sure Yamaha's engineers did a good job, and the insides of synths are normally not that hot. Still, capacitors are normally the first thing to fail. Depending on the circumstances, that can be sooner or later, but it's pretty much inevitable.

Andy

[Daniel Forró [e-mail] [YamahaDX]]

Exactly :-)

Daniel Forro

I just looked at the attached pictures and if I'm not mistaken those caps seem to be bipolar.
I see BP marked on the side and no strip indicating negative polarity but I'm not 100% sure.
If that's the case, you should use bipolar caps.Most of them are suited for audio applications too.

[Daniel Forró [e-mail] [YamahaDX]]

These are bipolar - BP. See the schematics.

Daniel Forro

Post by Takis ***@yahoo.com [YamahaDX]
These are just standard general purpose caps.
Any 100uf capacitor at the rated or higher voltage and temperature will do.
Truth is that any reputable branded cap should last forever as a replacement if genuine and properly stored since manufacture date.
I wouldn't expect any sound difference though.
Caps that could make a difference are almost always found on analog synths and in the voice(s) or filter(s) sections.
Decoupling capacitors or power supply filtering capacitors are there just for eliminating power supply ripple.

[[e-mail] [YamahaDX]]

They'll almost certainly be for smoothing the power supply, Jonas, not part of the audio path.

A capacitor that big would only be used for audio if it was driving a loudspeaker, or just possibly a headphones socket, but if so, there will be a direct connection from one capacitor lead to the socket, and the other lead will go to a chip, or another component, not to ground.

You can usually spot a ground plane connection quite easily, because there's a lot of it - a track that covers a large area of the board. Smoothing capacitors will have the negative lead soldered to ground. Ones that pass an audio signal won't.

The thing to do is over specify, provided they will still fit where the old ones were - higher voltage rating if you can, and a higher temperature rating.

Electrolytic capacitors are only rated for DC, so the only difference between 16V and 16V DC is how the manufacturer has marked them.

Andy

[Daniel Forró [e-mail] [YamahaDX]]

They are bipolar, and they are in audio path :-)

I suppose bipolar caps are also electrolytic, just no polarized, and they can work for AC.

Daniel Forro

Post by ***@ntlworld.com [YamahaDX]
They'll almost certainly be for smoothing the power supply, Jonas, not part of the audio path.
A capacitor that big would only be used for audio if it was driving a loudspeaker, or just possibly a headphones socket, but if so, there will be a direct connection from one capacitor lead to the socket, and the other lead will go to a chip, or another component, not to ground.
You can usually spot a ground plane connection quite easily, because there's a lot of it - a track that covers a large area of the board. Smoothing capacitors will have the negative lead soldered to ground. Ones that pass an audio signal won't.
The thing to do is over specify, provided they will still fit where the old ones were - higher voltage rating if you can, and a higher temperature rating.
Electrolytic capacitors are only rated for DC, so the only difference between 16V and 16V DC is how the manufacturer has marked them.
Andy

[[e-mail] [YamahaDX]]

Yes, bipolar capacitors in that sense are electrolytic. So, they may well have a rating in AC, or just in volts, without the DC.

I think they're probably two normal electrolytic capacitors back to back in the same can, in parallel (with positive of one connected to negative of the other and vice versa). I've done that across a small DC motor with two normal electrolytic capacitors (for strange reasons of my own) and they were fine - they both survived putting it into reverse. If you do that with just one electrolytic capacitor, it tends to explode when it's reverse biased - I've done that too, though not on purpose :)

[Bruce Wahler [e-mail] [YamahaDX]]

+1 -- on both counts! :-D

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
978.597.7008

I think they're [bi-polar or non-polar capacitors] probably two normal
electrolytic capacitors back to back in the same can, in parallel
(with positive of one connected to negative of the other and vice
versa).  I've done that across a small DC motor with two normal
electrolytic capacitors (for strange reasons of my own) and they were
fine - they both survived putting it into reverse.  If you do that
with just one electrolytic capacitor,  it tends to explode when it's
reverse biased - I've done that too, though not on purpose :)
------------------------------------------------------------------------

[[e-mail] [YamahaDX]]

Wow! I did not though the topic would get such attention! Thanks to all!

So a bit of mixed answers, audio path or not? Does it make a difference even, since I'll buy (hopefully) official Nichicon replacement (16 or 25V, 105°C and 100µF)? And what do you mean by bipolar capacitor? A capacitor that as no positive or negative pin? I will look again at the PCB but I think I saw a negative stripe on the capacitor plastic cover.

@pnetops: don't worry I got a eeprom dumper (Genius G540 which worked fine for my DX7 and various other chips) but if you'll stumble upon another one don't hesitate to post it! I think I'll try to dump the eeprom from one of my TF1 (and share it of course), at very least for backup purpose for me

@Daniel: does your TX'es got low SN# as well? I'm curious about it because the two DX7 MK1 I owned were different regarding the mainboard PCB : )

And don't worry about the PSU, actually that was the first thing I wanted to look at but infortunately it's not the easiest to dissassemble compared to thye TF1 modules (4 screws). I'll try again tonight.

[[e-mail] [YamahaDX]]

I thought I saw a negative stripe too, but it's the manufacturers name - stupidly positioned to look like one.

I haven't seen the service manual, but no doubt that's right, so what Daniel(?) said (sorry - losing track) - they're bipolar capacitors, in the audio path.

[Bruce Wahler [e-mail] [YamahaDX]]

A bipolar capacitor -- often called 'non-polar' -- is a special type of
electrolytic.  Standard electrolytics are, by design, polarized: they
act like a capacitor with voltage applied in one polarity; and pretty
much like a (bad) short circuit in the other polarity.  Since it's
possible to make smaller electrolytics at a certain {capacity * voltage}
compared to say, mica or ceramic types, they are used in applications
where the voltage on one side may go both higher and lower than the
other side -- ex: the output of an amplifier like a headphone amp --
where a regular electrolytic isn't suited to the job.

Most non-polar electrolytics are really two capacitors in one physical
package arranged like so:

        +   -      -   +
    -----||----------||-----

In either direction, one of the capacitors is acting as expected, and
the other one is a short.  Although bigger in size, one could just as
easily buy two 'regular' electrolytics and solder the (-) terminals
together -- that's kind of what the factory does, just more elegantly. 
You may find that the specific replacement value needed isn't easy to
source.

These devices are mostly used in audio circuits that require a large
combination of capacitance and working voltage.  I've *never* seen one
used as a bulk cap in a power supply.  Be careful:  in an audio circuit,
the power-supply maxim of "more is better" doesn't always apply.  More
capacitance will both increase the low-frequency response (good) and the
peak current and startup/settling time of the circuit (maybe, not as good).

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
978.597.7008

Post by ***@yahoo.fr [YamahaDX]
Wow! I did not though the topic would get such attention! Thanks to all!
So a bit of mixed answers, audio path or not? Does it make a
difference even, since I'll buy (hopefully) official Nichicon
replacement (16 or 25V, 105°C and 100µF)? And what do you mean by
bipolar capacitor? A capacitor that as no positive or negative pin? I
will look again at the PCB but I think I saw a negative stripe on the
capacitor plastic cover.
@pnetops: don't worry I got a eeprom dumper (Genius G540 which worked
fine for my DX7 and various other chips) but if you'll stumble upon
another one don't hesitate to post it! I think I'll try to dump the
eeprom from one of my TF1 (and share it of course), at very least for
backup purpose for me
@Daniel: does your TX'es got low SN# as well? I'm curious about it
because the two DX7 MK1 I owned were different regarding the mainboard
PCB : )
And don't worry about the PSU, actually that was the first thing I
wanted to look at but infortunately it's not the easiest to
dissassemble compared to thye TF1 modules (4 screws). I'll try again
tonight.

[[e-mail] [YamahaDX]]

Two capacitors In series, back to back, makes sense, yes, Bruce. I've just been to look for the lash up in question, out of curiosity, but it was a couple of years ago when I made it. It's hiding.

[[e-mail] [YamahaDX]]

Again thank you all for your feedback! AFter looking carefully there isn't a negative stripe so they're definitively bipolar.

Thanks for your answer Bruce I learnt something. I'll stay with the original specs 16V 100µF @85°C.

I did my "homework" Daniel but I'd rather have a second confirming answer since electronics has its intricaties and the language is not as rigorous as the mathematics behind them (even more as the language used for this exchange isn't my native one) : )
I'll be careful with the PSU, thanks for your advice, even if I guess I'm more than prepared for the job since I got few Vectrex capkit under my belt; but one's never too cautious when tinkering with high voltages!

Also my TX is rated at 100V (12W) and I got a AC to AC converter rated at 110V (100W) since I live in a 230V country, does this 10V difference will do some harm or not?

[Takis [e-mail] [YamahaDX]]

It would not make a difference since even if the AC amplitude after the
transformer turns out to be higher(remember that's there's always a
ratio not fixed voltages after transformers!) regulators are going to
take care of higher rectified DC input voltage with the cost of some
extra produced heat..

I think that about + - 10% (don't quote me on the exact number) of
rated input AC voltage will not do any harm as long as possible DC
regulators are within their input range.

Post by ***@yahoo.fr [YamahaDX]
Again thank you all for your feedback! AFter looking carefully there
isn't a negative stripe so they're definitively bipolar.
Thanks for your answer Bruce I learnt something. I'll stay with the
I did my "homework" Daniel but I'd rather have a second confirming
answer since electronics has its intricaties and the language is not
as rigorous as the mathematics behind them (even more as the language
used for this exchange isn't my native one) : )
I'll be careful with the PSU, thanks for your advice, even if I guess
I'm more than prepared for the job since I got few Vectrex capkit
under my belt; but one's never too cautious when tinkering with high
voltages!
Also my TX is rated at 100V (12W) and I got a AC to AC converter rated
at 110V (100W) since I live in a 230V country, does this 10V
difference will do some harm or not?

[[e-mail] [YamahaDX]]

Enclosed with this post you'll find the EEPROM DUMP of the TF1 module (I also uploaded it to DX files since many people don't get the emails notification along with the attachments). I read 2 TF1 module from my TX for good measure and they got the same checksum. So seeing few strings here and there (RAM TEST, LED TEST and so on) I think it's a good dump and all the TF1 got the same (unknown) ROM version which seems logical.

Funny thing: the header of the ROM starts with the following characters: LM 8950. Either this is totally unrelated or maybe it refers to a date code (50th week of '89, but that clashes with the story about the day one unit of the previous owner) and LM are the initials of the lead programmer, or either that relates to a '85 Yamaha sound chip (https://en.wikipedia.org/wiki/Yamaha_Y8950).

Guess we'll never know : )

[Daniel Forró [e-mail] [YamahaDX]]

Thank you for this BIN file and comparison with the other TF1. Great work! Now we can be sure it’s good. Anyway it would be interesting if somebody else can do the same with his TF modules
 I haven’t tools and knowledge.

Inside the code the OS version is not written.

Concerning LM 8950, this LM is standard ASCII code header for most of Yamaha SysEx dumps of RAM, but I have never seen it also in the case of OS.

AFAIK nobody knows what LM means. It can’t be the name of designer, as Japanese language doesn’t use L and when converting foreign words they use R. This fact together with general bad knowledge of English here caused more funny things in manuals and schematics, like Moduration - which is their idea how English can look when converted back from Japanese katakana transcription which is “mo-dyu-re-sho-n”).

My guess is it can be shortage for Load Memory
 who knows. Or Lunar Module? Lunch Meat? Loving Mother?

After LM there are usually two empty spaces, and four numbers (different for different instruments and data types) plus two characters describing data type. Sometimes there are not these 4 numbers, but more characters describing data type, and sometimes one number as last in the cases there can be more of such data types.

Of course the number is not a date.

Daniel Forro

Post by ***@yahoo.fr [YamahaDX]
Enclosed with this post you'll find the EEPROM DUMP of the TF1 module (I also uploaded it to DX files since many people don't get the emails notification along with the attachments). I read 2 TF1 module from my TX for good measure and they got the same checksum. So seeing few strings here and there (RAM TEST, LED TEST and so on) I think it's a good dump and all the TF1 got the same (unknown) ROM version which seems logical.
Funny thing: the header of the ROM starts with the following characters: LM 8950. Either this is totally unrelated or maybe it refers to a date code (50th week of '89, but that clashes with the story about the day one unit of the previous owner) and LM are the initials of the lead programmer, or either that relates to a '85 Yamaha sound chip (https://en.wikipedia.org/wiki/Yamaha_Y8950).
Guess we'll never know : )
_

[Daniel Forró [e-mail] [YamahaDX]]

Post by ***@yahoo.fr [YamahaDX]
Again thank you all for your feedback! AFter looking carefully there isn't a negative stripe so they're definitively bipolar.

I think also it would be better.

Post by ***@yahoo.fr [YamahaDX]
I did my "homework" Daniel but I'd rather have a second confirming answer since electronics has its intricaties and the language is not as rigorous as the mathematics behind them (even more as the language used for this exchange isn't my native one) : )

No problem, you are right, it’s good to ask to be sure. Not all sources on the net are reliable.

Post by ***@yahoo.fr [YamahaDX]
I'll be careful with the PSU, thanks for your advice, even if I guess I'm more than prepared for the job since I got few Vectrex capkit under my belt; but one's never too cautious when tinkering with high voltages!

It’s “soft” high voltage, but even so any electric shock is unpleasant.

Post by ***@yahoo.fr [YamahaDX]
Also my TX is rated at 100V (12W) and I got a AC to AC converter rated at 110V (100W) since I live in a 230V country, does this 10V difference will do some harm or not?

This shouldn’t be a problem. I have moved to Japan from Europe with lot of 230 V machines, use more big or small step-up transformers, some of them American 110/220, so machines get only 210 Volts and it works well. I thought maybe bigger problem can be frequency - 50/60 Hertz, but even this is OK.

Some TX rack have voltage selector - at least my both have it.

BTW my TX816 has SN 1973, TX416 1428.

Daniel Forro

[[e-mail] [YamahaDX]]

Thanks for your answer Takis!

@Daniel: Funny thing, when looking for a voltage selector (there's none on this one) I discovered that the Yamaha stickers reads TX116! It would have been a TX116 with 4 TF1 modules bought as option, interesting, I'll try to get in touch with the previous owner to see if he still has an invoice or something like that.

[[e-mail] [YamahaDX]]

PSU removed! I'm currently analysing it but it seems to be in perfect condition with no bulged nor leaking capacitors. There was a fair amount of screws to remove for the top cover then the side cover next to the PSU) but actually it was very logical so no much difficulties, at least on this model.

Another interesting thing to note: maybe a coincidence but the PSU (made by Yutaka electric MFG co., LTD) bears the inscription "LM PS NP 80900" (where PS may be power supply and NP 80900 a model number) so LM would reference at least the TX or maybe a Yamaha product line (or "Long Module" or "Large MIDI")?

[[e-mail] [YamahaDX]]

Mystory solved about the LM strings. From a French book on the MIDI:

"Sauf exception, les quatre derniers octets de cet en-tête identifient en ASCII le numéro du produit (8387 pour la DMP11, 8976 pour le TX81Z, etc.), tandis que les quatre premiers, toujours en ASCII, correspondent aux lettres "LM" (pour LM Division, Nippon Gakki Ltd, participant au développement logiciel des instruments) suivies de deux espaces."

Translated in english:

"Otherwise noted, the 4 last bytes of the header [of a sysex dump] matches in ASCII the product number (ie. 8387 for a DMP11, 8976 for a TX81Z, etc...), while the first 4 bytes, still in ASCII, are made from the letters "LM" (for LM Division, Nippon Gakki Ltd, one of the protagonists involved into the instrument's software R&D [firmware]) following by two spaces."

So 8950 will be the product number of the TF1, I'm currently looking for a list of all the instruments ID if it exists.

[Daniel Forró [e-mail] [YamahaDX]]

Thanks for this info, but still it didn’t explain the meaning of LM.

Few additions to your info:
- header is not indicating the instrument. It is header of SysEx memory dump. So some relative instruments can use the same numbers.

- header is not for one instrument, but for data type. One and the same instrument can have different numbers for Voices, Performances, Multi, Drumset etc. etc. Opposite - different instruments can use the same numbers.

- four numbers are not the last 4 characters of header, it’s followed by two other letters designated type

- not always there are 4 numbers, I have found also 8A21, 8A26, 8A27

- not always there are numbers - sometimes they are replaced by letters (like DX7 II D/FD Fractional Scaling or Microtune)

- there can be added one number at the end if instrument has more data blocks of the same type (like TX81z System or Microtune)

- not always there is LM__ - I have found instruments which have SK__ or PK__

Yamaha has been using this system around between 1986 - 1998, not on all machines. There were also other systems used in their instruments, sometimes even mixed in one instrument.

If you are interested in, here are some header numbers from my gear, and few others:

TX802 - 8952
TX81z - 8986 (error in the manual?), 8976
V50 - 8976, 8073, 8023
VL1 - 0117, 8101
WT11 - 8976, 8023, 8053
TG500 - 0065, 0066, 0040
SY85 - 0065, 0040
TG77 - 8101, 8104
SY77 - 8101
SY99 - 0040, 8101
TG33 - 0012, PK__2203
SY22/35 - PK__2203
TG55 - 8103
EOS B500 - 0010
DX11 - 8976, 8023
W5/7 - 0147
TQ5, YS100, YS200 - 8023, 8976, 8036
P500 - SK__2356
RM50 - 0087, 0017
DX7 II D/FD - 8973
MEP4 - 8969__
MFC10 - 0271
DMP9-8 - 8A27
DMP9-16 - 8A26
FX900 - 8724
REV5 - 8345
DMP7 - 8344
DMP11 - 8387
MSS1 - 8978
SPX900 - 8636
SPX990 - 8A21
SPX1000 - 8378

You can do your own research from Owner’s and Service Manuals...

Daniel Forro

Post by ***@yahoo.fr [YamahaDX]
"Sauf exception, les quatre derniers octets de cet en-tête identifient en ASCII le numéro du produit (8387 pour la DMP11, 8976 pour le TX81Z, etc.), tandis que les quatre premiers, toujours en ASCII, correspondent aux lettres "LM" (pour LM Division, Nippon Gakki Ltd, participant au développement logiciel des instruments) suivies de deux espaces."
"Otherwise noted, the 4 last bytes of the header [of a sysex dump] matches in ASCII the product number (ie. 8387 for a DMP11, 8976 for a TX81Z, etc...), while the first 4 bytes, still in ASCII, are made from the letters "LM" (for LM Division, Nippon Gakki Ltd, one of the protagonists involved into the instrument's software R&D [firmware]) following by two spaces."
So 8950 will be the product number of the TF1, I'm currently looking for a list of all the instruments ID if it exists.

[[e-mail] [YamahaDX]]

Thanks for your feedback Daniel.

This article (http://www.muzines.co.uk/articles/inside-views-yamaha/3468) says it means "Light & Music". Maybe SK and PK would be other companies or other divisions inside Yamaha.

Regarding the ID you're correct it seems to indicate a format and not an instrument thus explaining why it would change depending of the firmware's version (a newer firmware would support another SYX format etc...). This ID would be hexadecimal like many other data in the MIDI world (but still written in ASCII) so it's normal to have letters.

Regarding my TX the PSU is again in a very nice condition (no buldging/leaking caps nor tarnished solder near them) and I found that the big red wired jumper outside the PSU is actually the voltage selector! Plugged it would make it a 100V one, and unplugged a 220 (or 230V) one! I guessed that looking at the 400V capacitor (why out such a large value if your PSU is only 110V) and confirming that with the page 30 of the service manual.

[Daniel Forró [e-mail] [YamahaDX]]

Post by ***@yahoo.fr [YamahaDX]
Thanks for your feedback Daniel.

You are welcome!

Post by ***@yahoo.fr [YamahaDX]
This article (http://www.muzines.co.uk/articles/inside-views-yamaha/3468) says it means "Light & Music". Maybe SK and PK would be other companies or other divisions inside Yamaha.

It’s quite possible, PK is usually used for Portable Keyboards. But I think nowadays Yamaha has different internal structure.

Post by ***@yahoo.fr [YamahaDX]
Regarding the ID you're correct it seems to indicate a format and not an instrument thus explaining why it would change depending of the firmware's version (a newer firmware would support another SYX format etc
).

No, it is not changed - the SysEx data format stays the same even when new version of OS came. It would be a great confusion to change data format when OS version changes. Besides OS version changes were not publicly known and announced, only authorized serveice technicians were informed


Post by ***@yahoo.fr [YamahaDX]
This ID would be hexadecimal like many other data in the MIDI world (but still written in ASCII) so it's normal to have letters.

I suppose you wanted to say “binary” - MIDI world is not hexadecimal nor decimal nor ASCII. It is only transcribed that way for simplicity.

And if you mean that this letter “A” as a part of four characters in the header is hexadecimal number, that’s wrong. It’s just ASCII code.
Number “A” in hex would have only four bits (binary 1010), but ASCII “A” in the header has one full byte - in hex it is 41 (binary 01000001). Am I right? Can you see the difference?

Post by ***@yahoo.fr [YamahaDX]
Regarding my TX the PSU is again in a very nice condition (no buldging/leaking caps nor tarnished solder near them) and I found that the big red wired jumper outside the PSU is actually the voltage selector! Plugged it would make it a 100V one, and unplugged a 220 (or 230V) one!

Great! Probably my TX's with voltage selector are slightly different concerning this red jumper. It’s longer time I did repairs and complete recapping of my TX's and TF's, so I don’t remember such details at all. Too many instruments I did in last years and still there’s a lot of others as they are aging, too.

Post by ***@yahoo.fr [YamahaDX]
I guessed that looking at the 400V capacitor (why out such a large value if your PSU is only 110V) and confirming that with the page 30 of the service manual.

Maybe to have enough reserve for possible power spikes?

Daniel Forro

[Bruce Wahler [e-mail] [YamahaDX]]

<snip>

Post by ***@yahoo.fr [YamahaDX]
I guessed that looking at the 400V capacitor (why out such a large
value if your PSU is only 110V) and confirming that with the page 30
of the service manual.

Maybe to have enough reserve for possible power spikes?

110V is really 120V in many countries 120V RMS is 170V peak; 340V p-p .
if the capacitor cannot get discharged in time.  Probably to cover for
UL/CSA/TUV/etc. safety requirements.

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
978.597.7008

[[e-mail] [YamahaDX]]

For the ones interested here's a complete electrolytic capacitors list of both a TF1 module and the PSU:

TF1 MODULE

(all caps are 85°C rated otherwise stated)

[Bipolar] Nichicon 16V 100µF x 2
SME 16V 220 µF x 4
SME 16V 10µF x 3
SME 16V 33µF x 1
ACE 50V 1µF x 2
[Bipolar] SME 25V 4.7µF x 1

- - -

POWER SUPPLY (Yamaha MRF8 // LM PS NP 80900 YUTAKA ELECTRIC)

(all caps are 105°C stated otherwise noted)

C5 C6 C15 C16 - Marcon 35V 10µF
C7 C8 - Marcon 200WV 470µF 85°C <<< shouldn't they be of a higher voltage to support the 230V operation?
C9 - Marcon 400V 220µF
C17 - Marcon 35V 22µF
C18 - Marcon 35V 100µF
C24 C25 - Marcon 25V 2200µF
C29 C30 C31 - Marcon 10V 4700µF
C32 C33 - Marcon 25V 330µF

[[e-mail] [YamahaDX]]

I'll change all the electrolytics of the PSU. Should I order low ESR ones or is this only for the two bipolar 16V 100µF on the TF1 module? Regarding the PSU still, this time taking 105°C instead of 85°C ones?

@Daniel: if you have it handy I gladly have your power supply schematics, they aren't part of the service manual nor available on the web it seems. Cheers!

[Daniel Forró [e-mail] [YamahaDX]]

I don’t know if it’s necessary to have low ESR caps for PSU, maybe somebody can answer this.

I would use 105 grades.

I will send schematics to your address.

Daniel Forro

Post by ***@yahoo.fr [YamahaDX]
I'll change all the electrolytics of the PSU. Should I order low ESR ones or is this only for the two bipolar 16V 100µF on the TF1 module? Regarding the PSU still, this time taking 105°C instead of 85°C ones?
@Daniel: if you have it handy I gladly have your power supply schematics, they aren't part of the service manual nor available on the web it seems. Cheers!

[[e-mail] [YamahaDX]]

I depends on the design of the PSU. In some cases, low ESR capacitors are specified in the datasheet of the voltage regulator chip, so that's what you need to use.

I can't think of a reason why replacing a higher ESR capacitor with a low ESR one would be a problem. Doing it the other way around definitely can be a problem - at the very least, doing it to a PSU could cause more ripple or hum. At worst, it could destabilise the voltage regulator and do a lot of damage.

Personally, I'd count most of the "cost" of a repair like that in terms of my time to do it. Spending more on the components isn't likely to bankrupt you. Using better specification ones makes it less likely that you'll have to do it again any time soon.

Andy

[Bruce Wahler [e-mail] [YamahaDX]]

I have actually seen switching power supply designs that will not work
properly with low-ESR capacitors.  The power IC manufacturer was using
the higher resistance for stability in the feedback loop, IIRC.

That said, these designs all came out in the late '90s or early '00s,
long after the TX816 was designed, so I don't think it's a problem
here.  But it just goes to show:  if some phenomenon exists, however
'undesirable' to most, some designer somewhere will find a use for it! ;-)

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
978.597.7008

I depends on the design of the PSU.  In some cases, low ESR capacitors
are specified in the datasheet of the voltage regulator chip, so
that's what you need to use.
I can't think of a reason why replacing a higher ESR capacitor with a
low ESR one would be a problem.  Doing it the other way around
definitely can be a problem - at the very least, doing it to a PSU
could cause more ripple or hum.  At worst, it could destabilise the
voltage regulator and do a lot of damage.
Personally, I'd count most of the "cost" of a repair like that in
terms of my time to do it.  Spending more on the components isn't
likely to bankrupt you.  Using better specification ones makes it less
likely that you'll have to do it again any time soon.
Andy

[[e-mail] [YamahaDX]]

Thanks for your feedback, I will proceed according to your suggestions!

[Daniel Forró [e-mail] [YamahaDX]]

After your study of PSU schematics you will understand it’s not necessary.

They used two caps in series because on machines with voltage selector they are used separately when 100 V are selected. Then 200 V is enough reserve.

When 220 Volt is selected, they are connected in series, which makes their total value 235 uF, and voltage is doubled - 400 V. Which is similar to C9 value connected behind L2.

At least if I understand well capacitor math :-)

Daniel Forro

Post by ***@yahoo.fr [YamahaDX]
C7 C8 - Marcon 200WV 470µF 85°C <<< shouldn't they be of a higher voltage to support the 230V operation?

[Daniel Forró [e-mail] [YamahaDX]]

In my schematics two of these connected for filtering +5 V rail were rated 10 V.

Daniel Forro

Post by ***@yahoo.fr [YamahaDX]
TF1 MODULE
SME 16V 220 µF x 4

['[e-mail]' [e-mail] [YamahaDX]]

[Daniel Forró [e-mail] [YamahaDX]]

Exactly, but usually it’s written in documents as underscore to indicate empty spaces :-)

Daniel Forro

I want to add: when in the docs you see "LM__xxxxxx" the "___" is not really 2 underscore characters but 2 space characters (ascii nr 32 or hexadecimal 20).
MT

[Daniel Forró [e-mail] [YamahaDX]]

Post by ***@yahoo.fr [YamahaDX]
Wow! I did not though the topic would get such attention! Thanks to all!
So a bit of mixed answers, audio path or not?

What is so questionable about it? Schematics is the ultimate reference and speaks clearly. These two caps are BP type.

Post by ***@yahoo.fr [YamahaDX]
Does it make a difference even, since I'll buy (hopefully) official Nichicon replacement (16 or 25V, 105°C and 100µF)?

Just buy what it is: Nichicon or Panasonic 100 uF/16 V, 85 C. Common component, try Mouser, Digikey, Jameco...

Post by ***@yahoo.fr [YamahaDX]
And what do you mean by bipolar capacitor? A capacitor that as no positive or negative pin?

Uncle Google has a lot of answers, if you ask him:

https://electronics.stackexchange.com/questions/304445/what-is-a-bipolar-capacitor-and-when-is-it-used/304448 <https://electronics.stackexchange.com/questions/304445/what-is-a-bipolar-capacitor-and-when-is-it-used/304448>

Do your homework :-)

Post by ***@yahoo.fr [YamahaDX]
I will look again at the PCB but I think I saw a negative stripe on the capacitor plastic cover.

I don’t think so.

Post by ***@yahoo.fr [YamahaDX]
@pnetops: don't worry I got a eeprom dumper (Genius G540 which worked fine for my DX7 and various other chips) but if you'll stumble upon another one don't hesitate to post it! I think I'll try to dump the eeprom from one of my TF1 (and share it of course), at very least for backup purpose for me

That’s a great idea! Thanks in advance.

Post by ***@yahoo.fr [YamahaDX]
@Daniel: does your TX'es got low SN# as well?

I think so, but I can look tomorrow, it’s deeply in one of my rack cases buried in hundreds of cables and now is 2 AM here on this side of the globe
 Probably yes, as there were not much of them produced.

Post by ***@yahoo.fr [YamahaDX]
I'm curious about it because the two DX7 MK1 I owned were different regarding the mainboard PCB : )

AFAIK there were more modifications of DX7, around 14
 later versions have much less chips on PCB. Also about 11 changes of OS.

Post by ***@yahoo.fr [YamahaDX]
And don't worry about the PSU, actually that was the first thing I wanted to look at but infortunately it's not the easiest to dissassemble compared to thye TF1 modules (4 screws). I'll try again tonight.

As I said, it’s a nightmare. Not only to get it out, but then disassemble the PSU box itself, and get out the PCB. If I remember well, there are four screws with short distance pipes (? I don’t know exact term), some nuts are hidden inside and difficult to access them


Be careful, three biggest caps on primary side are high voltage (rated to 400 V), they can be loaded. Before touching anything around them unload them first by shorting their pins.

Daniel Forro

[[e-mail] [YamahaDX]]

They are most likely dc decouplers. The safest way to go without further knowledge is to replace them with the same value caps. What is important is the uF value (especially if they do filtering), the voltage (bigger voltage tolerance is ok, but the larger the voltage the larger the capacitor, this can be an issue if they are on a fairly packed board), and the temp rating is basically inconsequential for most things, i.e. there are only usually two ratings, one is for 'commercial', the other is sometimes referred to as 'military' grade. So choose 100uF, 16v or 25v and 85c or 105c if they are similar price.

[Daniel Forró [e-mail] [YamahaDX]]

Further knowledge can be found in the Service Manual :-)

Modern caps are smaller than old ones so the size is no more problem. There are even very small caps available (more expensive). 105 grades are more expensive.

Daniel Forro

Post by ***@yahoo.com [YamahaDX]
They are most likely dc decouplers. The safest way to go without further knowledge is to replace them with the same value caps. What is important is the uF value (especially if they do filtering), the voltage (bigger voltage tolerance is ok, but the larger the voltage the larger the capacitor, this can be an issue if they are on a fairly packed board), and the temp rating is basically inconsequential for most things, i.e. there are only usually two ratings, one is for 'commercial', the other is sometimes referred to as 'military' grade. So choose 100uF, 16v or 25v and 85c or 105c if they are similar price.

[[e-mail] [YamahaDX]]

BTW - if you want to post the ROM(s) to me, I'll dump it for the community, and if you can find a newer version I can burn that for you at the same time and then send it back to you.

[Daniel Forró [e-mail] [YamahaDX]]

Congratulations! It’s a great machine.

Post by ***@yahoo.fr [YamahaDX]
Hi,
I just sold locally my DX7 along with its DX MAX 3 card (along with a Sony BVM monitor) to get the beast that's the TX816 (well actually a TX516 since it has 5 TF1s).
I was told it's a day one model, the previous owner bought it directly from a Yamaha dealer in Japan the day the first units came out of the factory (SN# 1010, is there anyone here who like to share its TX SN too? the TF1's SN# are also in the 4 digits range).

Yamaha serial numbers of instruments for the market starts always from 1000. More early numbers are prototypes for internal use at Yamaha.

Post by ***@yahoo.fr [YamahaDX]
Well that was the story about this particular unit. Now it's working (I tested it at the seller's) but since It's 32 years old I'm dissasembling it for the obligatory maintenance before using it at home and, wow! what a surprise I got. The TF1's PCB are in a pristine condition, all the (Sanyo) lithium cells are still 3V (!) and only two capacitors per TF1 board are slightly bulged (always the same, the biggests, near the bottom left corner of the PCB), but none are leaking. Talk about a marvel of Japanese engineering!

Yes, that’s so. I just got TG55 from 1989, and after opening it for checking I had the same surprise - it’s like a new machine. I’m in Japan, when we consider local high temperature and high humidity in summers it’s just unbelievable to find it in such condition. Probably it was somewhere in air-conditioned studio, or closed somewhere and not used. Some of my newer Yamaha machines I brought from Europe have rusty panels inside after 14 years here. Partly not so good metal is guilty, partly that humidity - my studio is not air-conditioned...

Post by ***@yahoo.fr [YamahaDX]
So now I'm in the quest of changing these 5x2=10 capacitors (I know I should do them all to let them age at the same rate but I'd rather modify this machine only when I really have to in order to not hurt it).

There shouldn’t be problem with TF1 temperature, it’s not PSU. 85 grades is OK for caps which are not in PSU.

There two values are bipolar caps, so use the same. When I have changed those in my 12 TF1’s, I have used some beautiful green color caps :-)

Post by ***@yahoo.fr [YamahaDX]
I attached pics of the capacitors and the PCB in order to let you tell me if the capacitors are on the audio path (I think not, they are likely to be filtering the power supply but I'm no expert).

Yes, they are in audio path. I don’t think they have any influence on the sound.

BTW I don’t hear anything particular or legendary in the sound of TF1 or DX7 Mk I, it’s just the second generation of Yamaha algorithm synthesis. The sound is defined by FM synthesis. If you mean low bit DAC and all that noise or intermodulation and frequency mirroring distortion, that’s not so legendary, I would call it rather problem. I personally prefer more clean sound of later FM machines.

Post by ***@yahoo.fr [YamahaDX]
Another subsidiary question: does the ROM of the individual TF1 module has been dumped? I cannot find a reference to this. Like I said earlier I'd rather not tinker too much with the insides of the TX but if it could help someone or the community at large I'd be willing to take the chance to do it. Let me know.

It seems not, I haven’t seen yet TF1 dumps, and don’t know anything about possible different OS versions.

Post by ***@yahoo.fr [YamahaDX]
Cheers in advance for your feedback,
Jonas

When you do such maintenance, check also control unit, and of course PSU - maybe you will find problematic caps there. It’s not Yamaha product, and it’s pretty difficult to dig it out and disassemble. I have changed all caps there in my TX816 and TX416, some of them were big - fortunately modern electrolytic caps are smaller than old ones. If you need schematics, I can send it to you if it’s not in File section of this group. It’s rather complex circuit with optocouplers between primary and secondary circuits
 not so common and simple.

TX816 Service manual and full schematics is easily to find elsewhere on the net in more versions. I have all.

Good luck!

Daniel Forro