Sony STR 7055 overheating problem

[roger2]

Is it necessary to cut the leg of the resistor to measure the voltage?

No. The resistor would be measured in place and with the receiver powered on. No signal, volume turned down.

I would not suggest doing this if you had not already taken similar voltage readings in order to set the bias, which you did do several times according to your earlier posts. If you do not feel capable of taking a live reading safely, then by all means don't do it.

But if you are able to do this, you can have knowledge of what is going on as opposed to speculation. If, for example, it is a 1 watt resistor, then it should be dissipating less than 1 watt. By providing the information I requested in my last post, we can determine this. From a distance and over the internet, readers here can not judge the significance of terms like "hot" and "smells"

I understand the receiver will be moving on regardless, and that is cool. Nothing wrong with keeping the wife happy


EDIT: forgot to specify earlier, but if you do this reading you would be looking at DC voltage, not AC

 

[Kutiltim]

2 Binkman:
you are right man! but there is not to fight for. I have some other receiver that i like too, even if the Sony has more pleasant warm sound.

Yes, I can try to put it in the garage, if the smell will go away.

 

[Billski]

Yee haw! I have a 7065 with the same stinky issue. It's that same smell that I've encountered in many older pieces of electronics, especially those that run hot. I've had my 7065 up pretty loud using some JBL 4311s that rock the room and it's never clipped or distorted in the year I've had it. Granted, I only play it when the wife is gone (maybe 30 hours a year). I've left it on overnight and the smell remains, but nothing has popped on me yet.

While I'm well-trained in these matters, in retirement I find myself exceedingly lazy, to the point of not even blowing the dust off of it. I KNOW the smell of burning semiconductors, capacitors and pcb-laden transformers, and it's not that smell. So it must be just dust. Some people are cleaner than others. I picked up a receiver from my inlaws and it had no smells. She was obsessive about cleaning her house. I never saw a spec of dust.

Alas, the partner problem. My wife too is hypersensitive. I once brought home a pair of L100s for very short money from a chain smoker. I left them in the shed out back to air out. Not only didn't the smell come out, the shed caught the smell too. Sold them to a fellow for what I paid for them, and he said he would entirely sand down the wood on every piece in the cabinet and get new covers. I was doubtful, since the speaker cones are porous and god knows that particles settled into every crevace in the speakers. It was heartbreaking to let it go, but there was no other choice. Luckily for your, the receiver will clean up,

 

[eschenborn]

This is a reply to an old thread and the receiver in question might have moved on.

I am repairing-restoring a SONY STR-7055. I can confirm that the power supply corner of the main amp board does get hot; it is the hottest area if you hold your hand over the slits in the cover, way hotter than the power transistor heatsinks.

This is hot by design and obviously relatively safe over time.

BUT: I suspect the smell some of you percieve is not from the components heated by the hot resistors but from the evaporating electrolytic in the Nichicon capacitors used throughout the boards. these get leaky and smell. they also stop working and might damage the amp. I have the same smell in my machine. Recap already started.

other than the ELNA caps which SONY still used in the previous receiver generation (STR-60X5), the Nichicons leak and smell.
Problem solution: Total recap. The smell will go away immediately.

I encountered the same problem in a STR-7025 and a TA-3650.