Hello everyone,
Normally I am troubleshooting my selfbuild equipment, but an uneducated friend of mine fried one channel of the Yamaha MX-630 Power amplifier by shorting the speakerwires.
Now all the Sankens have to be replaced including the drivers.
What puzzles me is that some small resistors (not in the powerchain) are also overheated. Maybe they were underrated by designmisstake, I am not shure. I also would like to replace them because I think it is a fire hazard and a great liabillity factor.
You help your friend out but created a fire bomb and destroyed his house (including the amplifier) in the end.
I have tried to contact Yamaha directly in order to get a schematic or service manual but I have been not succesfull as of yet.
Can somebody help me to retrieve at least a schematic of this amplifier ?
I would be very greatfull.
Thanks for reading.
Bij voorbaat dank.
Govert-Jan
Normally I am troubleshooting my selfbuild equipment, but an uneducated friend of mine fried one channel of the Yamaha MX-630 Power amplifier by shorting the speakerwires.
Now all the Sankens have to be replaced including the drivers.
What puzzles me is that some small resistors (not in the powerchain) are also overheated. Maybe they were underrated by designmisstake, I am not shure. I also would like to replace them because I think it is a fire hazard and a great liabillity factor.
You help your friend out but created a fire bomb and destroyed his house (including the amplifier) in the end.
I have tried to contact Yamaha directly in order to get a schematic or service manual but I have been not succesfull as of yet.
Can somebody help me to retrieve at least a schematic of this amplifier ?
I would be very greatfull.
Thanks for reading.
Bij voorbaat dank.
Govert-Jan
Congratulations and thanks Daniel
This is what i think is a good friend... a good moderator... when needed to be hard he knows how to do with kind way.... when are visiting their forum as one of us, he is friendly and do not think as many
THIS IS ALL MINE!
This way, wonderfull and kind work, helping us.
Carlos
This is what i think is a good friend... a good moderator... when needed to be hard he knows how to do with kind way.... when are visiting their forum as one of us, he is friendly and do not think as many
THIS IS ALL MINE!
This way, wonderfull and kind work, helping us.
Carlos
Thank you very much!
Dear Peter,
Thank you very much for helping me out !
You are one of the most resourcefull persons I have ever met.
Is it not wonderfull to share information this way !
One day hopefully I will fly one of those well crafted products you make in Seattle !
Cheers to you.
Thanks everybody for thinking with me. What a great teamwork here on this website.
With respect,
G.J.S.Groenendijk
Dear Peter,
Thank you very much for helping me out !
You are one of the most resourcefull persons I have ever met.
Is it not wonderfull to share information this way !
One day hopefully I will fly one of those well crafted products you make in Seattle !
Cheers to you.
Thanks everybody for thinking with me. What a great teamwork here on this website.
With respect,
G.J.S.Groenendijk
succesfull repair
I would like to inform you all, especially thanks to Peter Daniel, that the amplifier has been restored to its previous condition.
It had taken me two days in a span of two weeks to get it fixed.
Downloading transistor data and finding replacements with the correct specifications also took a long time.
Those Japs ( my wife is one! ) discontinue stuff like rabbits !
It was obvious for me to replace the output transistors and drivers but I almost could not believe I had to replace all semiconductors in the soundstage and the protection circuit as well.
The PCB has more wire bridges than components on it.
As you can see from the schematics there are no active current sources at all.
Not for the diff input and not for the VAS. And on top of everything there is no bootstrapping (common when there are no active current sources like aksa, P3a).
The schematic is also overwhelmed by compansation caps.
The amp can produce good bass because the input capacitor and the feedback capacitor (both poor quality electrolytics!) are huge compared to there resistive loading.
The rest of the sound is poor to my ears. There is a hole in the mid's and the highs are made of plastic.
Tiny heatsinks as well.
Must have been a panic product from Yamaha.
The conclusion is that I have managed to repair this mediocre equipment cheaply and made a friend very happy again. The cost was about 70 euro's.
By the way he has Tannoy defenition D900's , lucky ducky.
No money to let me make a real amplifier for him.
One more thing,
DestroyerX ( Carlos) must stay with us!
Cheers to you all !
Govert-Jan
I would like to inform you all, especially thanks to Peter Daniel, that the amplifier has been restored to its previous condition.
It had taken me two days in a span of two weeks to get it fixed.
Downloading transistor data and finding replacements with the correct specifications also took a long time.
Those Japs ( my wife is one! ) discontinue stuff like rabbits !
It was obvious for me to replace the output transistors and drivers but I almost could not believe I had to replace all semiconductors in the soundstage and the protection circuit as well.
The PCB has more wire bridges than components on it.
As you can see from the schematics there are no active current sources at all.
Not for the diff input and not for the VAS. And on top of everything there is no bootstrapping (common when there are no active current sources like aksa, P3a).
The schematic is also overwhelmed by compansation caps.
The amp can produce good bass because the input capacitor and the feedback capacitor (both poor quality electrolytics!) are huge compared to there resistive loading.
The rest of the sound is poor to my ears. There is a hole in the mid's and the highs are made of plastic.
Tiny heatsinks as well.
Must have been a panic product from Yamaha.
The conclusion is that I have managed to repair this mediocre equipment cheaply and made a friend very happy again. The cost was about 70 euro's.
By the way he has Tannoy defenition D900's , lucky ducky.
No money to let me make a real amplifier for him.
One more thing,
DestroyerX ( Carlos) must stay with us!
Cheers to you all !
Govert-Jan
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