Sony ES series amp overheating halfway

Hi Folks,
I would be really interested in some insights on how to resolve my overheating problem on my old Sony TA-F444ES II amplifier
Essentially it is working fine, but when I open the volume knob a little over halfway it will go into ‘preotection mode’ after a couple of minutes due to over heating.
I bought it about 30 years ago, have recently cleaned it (though it didn’t need much), but have no idea how to fix this.
Would I need to take the heatsink off and ‘re-glue’ it on?
Easier/better to add ventilators (sounds like an uggly (and noisy) solution) ?

Any suggestions?

Here’s a link to what the beast looks like: http://www.highfidelityreview.com/inside-out-sony-ta-f444es.html

Thanks a lot in advance!
Oscar

Hi elbie,

I use exactly the same Amp - also bought about 30 years ago - for not too less money.

The issue you describe has nothing to do with Volumio - i’m quite sure.

Could be it is required to adjust the quiescent current - or simply replace some of the electrolytic condensers (after so much working hours).
Never ever put some other device on top of this Amp if you want to use it for another 30 years :wink: (to make sure heat is getting off)

This is a rrrrreally great sounding amp and please do not add noisy fans - it hasn’t deserved this.
It’s driving a pair of Dynaudio MSP110 speakers at my workbench which i use to do testing on all my Raspberry based and other devices.

Please rethink to try repairing it yourself - it is worth to be reviewed by a specialist.

  • Josef

@Josh2000 Thanks mate! Appreciate the input/feedback.
On low volume output not much heat is produced, so would hope the quiescent current is what it should, but more fedback is appreciated.
I noticed on other forums some folks change their caps, is that like a logical thing to do on old amps like this?
What would be the reason for this? They are physically deteriorated by usage & time and therefore produce heat?
The quality of the sound is still great though.

The area where I live is kinda rural, so not many electrocs shops around here. Some expert guidance would be appreciated.
I actually spend some school time in the electro/electronics field so am somewhat comfortable repairing, but need to understand what to look for and what to do as that dates about 30 years back as well…

Hi @Capthijs,
You seem to be knowledgable on this. Would you mind lending a hand to an expat?

Thanks all!
Oscar

Hi Oscar,

Please see “DC BIAS Adjustment” in the service manual page 11.
You can get it there:
https://elektrotanya.com/sony_ta-f444es_full_sm.pdf/download.html

Regarding the electrolytic condensers:

Please check first if they look blown up or if there is some kind of “grind” around them on the PCB. If yes replace them.
Next measure with your fingers if they get warm or even hot at louder levels - take care to not touch high voltage parts. If they get warm or hot replace them. Take care !!!

They used real high quality electrolytic condensers in this amp. (The ones in mine are still o.k. after 30 years but i never had some other devices on top of it that could influence the thermal flow).
If you really have to replace them (usually the big ones - but check all of them) be sure to choose also high quality brands like e.g. Nichikon or Panasonic.
There are special types for music/sound/amps/hifi - take these ones.
Yes they are expensive but worth the money. Don’t even think about buying the cheap chinese ones !

For more detailed information you could look at: ( or Google :wink:)
http://www.eng-tips.com/viewthread.cfm?qid=237142
http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html
http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html
https://electronics.stackexchange.com/questions/253976/what-happened-to-electrolytic-capacitors-in-the-21st-century

or YouTube:
https://www.youtube.com/watch?v=J9-k0HgGzbU

I think this is getting a bit off topic as this is not a repair forum.
Please send me a PM if you have further questions.

I wish you good luck to make this “underestimated” but really good sounding amp working like in the days when you have bought it.

  • Josef

Super cool feedback, thanks !!
I am away from home for atleast a week, so bear with me on response. I do accept your invite for a PM if needed. :smiley:
Thanks again,
Oscar

Hi Guys!
I have the same problem of overheating in my sony ta da9000es
It works on zero all the time , and it was covered by matantz sr7011 on top of it
Now protectors click after 12 minutes, but in minus 13 it still work OK

So, what shouls i do with it?

Thanks

Hard to tell. Possible causes can be:

  • DC offset/BIAS at the output, which causes the transistors to start conducting => Adjust to DC output to 0mV
    image

  • Voltage rails unbalanced, causing asymmetrical amplification => Adjust the voltages rails

  • Capacitors have a bold top => Replace all with identical ones and perform adjustments
    image

  • As this is a A/B class, check if there is distortion between positive an negative amplification