[YamahaDX] Dx7s transformer

[Lee [e-mail] [YamahaDX]]

Dear all

Does anyone know the spec of the DX7s power transformer off the top of their head?
This pic suggests it has 2 secondaries.

One x-0-x and one x-0

Different voltages.
I presume hefty current rating too?


http://www.keyboardkountry.com/yamaha-dx7-9-transformer/

Sent from my iPhone

[Daniel Forró [e-mail] [YamahaDX]]

Output voltage from power circuit are +/- 12 V and +5 V, so secondary voltages are probably little bit more.

But that transformer is more complex - there’s another primary circuit for feedback circuit with opto element, I suppose it serves for better voltage stabilization, it can balance voltage inaccuracies which can occur on primary side from power line.

Daniel Forro

Post by Lee ***@yahoo.co.uk [YamahaDX]
Dear all
Does anyone know the spec of the DX7s power transformer off the top of their head?
This pic suggests it has 2 secondaries.
One x-0-x and one x-0
Different voltages.
I presume hefty current rating too?
http://www.keyboardkountry.com/yamaha-dx7-9-transformer/ <http://www.keyboardkountry.com/yamaha-dx7-9-transformer/>
Sent from my iPhone

[Jacob Vosmaer [e-mail] [YamahaDX]]

It's odd how that transformer does not seem to be mentioned in the parts
lists of the service manual. The only thing I found is a type number
'TM163A' or 'TMI63A' in the schematic.

It's part of a switch-mode power supply. The feedback loop via the shunt
regulator and optocoupler only controls the 5V line. Whatever adjustments
that makes to the duty cycle are applied to +/-12V as well. No idea how to
pick a replacement transformer.

Post by Daniel Forró ***@yahoo.com [YamahaDX]
Output voltage from power circuit are +/- 12 V and +5 V, so secondary
voltages are probably little bit more.
But that transformer is more complex - there’s another primary circuit for
feedback circuit with opto element, I suppose it serves for better voltage
stabilization, it can balance voltage inaccuracies which can occur on
primary side from power line.
Daniel Forro
Dear all
Does anyone know the spec of the DX7s power transformer off the top of their head?
This pic suggests it has 2 secondaries.
One x-0-x and one x-0
Different voltages.
I presume hefty current rating too?
http://www.keyboardkountry.com/yamaha-dx7-9-transformer/
Sent from my iPhone

[Daniel Forró [e-mail] [YamahaDX]]

Thanks for additional explanation :-)

Exact spec of transformer is not written, as it is supposed it will be replaced by the same model type or part number when necessary. And this info is written in service manuals, I just checked some.

Daniel Forro

It's odd how that transformer does not seem to be mentioned in the parts lists of the service manual. The only thing I found is a type number 'TM163A' or 'TMI63A' in the schematic.
It's part of a switch-mode power supply. The feedback loop via the shunt regulator and optocoupler only controls the 5V line. Whatever adjustments that makes to the duty cycle are applied to +/-12V as well. No idea how to pick a replacement transformer.
Output voltage from power circuit are +/- 12 V and +5 V, so secondary voltages are probably little bit more.
But that transformer is more complex - there’s another primary circuit for feedback circuit with opto element, I suppose it serves for better voltage stabilization, it can balance voltage inaccuracies which can occur on primary side from power line.
Daniel Forro

Post by Lee ***@yahoo.co.uk [YamahaDX]
Dear all
Does anyone know the spec of the DX7s power transformer off the top of their head?
This pic suggests it has 2 secondaries.
One x-0-x and one x-0
Different voltages.
I presume hefty current rating too?
http://www.keyboardkountry.com/yamaha-dx7-9-transformer/ <http://www.keyboardkountry.com/yamaha-dx7-9-transformer/>
Sent from my iPhone

[Lee Borrell [e-mail] [YamahaDX]]

Thanks guys - it is now evident that simple replacement is not possible,which is what I was after finding out.
Thanks for your definitive information.

LEE



From: "Daniel Forró ***@yahoo.com [YamahaDX]" <***@yahoogroups.com>
To: ***@yahoogroups.com
Sent: Saturday, 3 March 2018, 10:23
Subject: Re: [YamahaDX] Dx7s transformer

  Thanks for additional explanation :-) 
Exact spec of transformer is not written, as it is supposed it will be replaced by the same model type or part number when necessary. And this info is written in service manuals, I just checked some.

Daniel Forro



On Mar 3, 2018, at 18:19, Jacob Vosmaer ***@jacobvosmaer.nl [YamahaDX] <***@yahoogroups.com> wrote:


It's odd how that transformer does not seem to be mentioned in the parts lists of the service manual. The only thing I found is a type number 'TM163A' or 'TMI63A' in the schematic.
It's part of a switch-mode power supply. The feedback loop via the shunt regulator and optocoupler only controls the 5V line. Whatever adjustments that makes to the duty cycle are applied to +/-12V as well. No idea how to pick a replacement transformer.
2018-03-03 5:47 GMT+01:00 Daniel Forró ***@yahoo.com [YamahaDX] <***@yahoogroups.com>:


Output voltage from power circuit are +/- 12 V and +5 V, so secondary voltages are probably little bit more.
But that transformer is more complex - there’s another primary circuit for feedback circuit with opto element, I suppose it serves for better voltage stabilization, it can balance voltage inaccuracies which can occur on primary side from power line.
Daniel Forro


On Mar 3, 2018, at 12:13, Lee ***@yahoo.co.uk [YamahaDX] <***@yahoogroups.com> wrote:


Dear all
Does anyone know the spec of the DX7s power transformer off the top of their head?This pic suggests it has 2 secondaries.
One x-0-x and one x-0 
Different voltages.I presume hefty current rating too?

http://www.keyboardkountry. com/yamaha-dx7-9-transformer/

Sent from my iPhone








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