Help! Yamaha R-500 died today

V

version2

New Member
I have Yamaha R-500 stereo receiver. I believe its 1983, last year of analog receiver before yamaha changed to digital receivers. It has brushed silver face with green glowing tuner dial, with wood case. I want to save it for nostalgia reasons. It was working until this morning. I pushed the power button, and the delayed relay click that usually happens after a few seconds never happened. Everything lights up on the face, but no sound. I opened the case and looked inside but can't see anything smoked. I had a competent techie replace the STK 2040 amplifier chip a few years ago, one for one exact part replacement, and it has worked fine since then. Other than that, its all original parts. Is there a cheap easy fix for this? I'm not a techie, I don't have ability to do diagnostics, no equipment. I can do simple part replacement if I know which part to order off the net, I have solder gun. But that's about it. So don't talk over my head. Is this receiver aging out? I'd like to keep it going. Any help is appreciated. Thanks.
 
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I removed top of the case again, and was looking around inside with a flashlight. I pushed in the power button. Face lit up, but no relay click, and no sound. Suddenly after about 5 minutes, the relay clicked and I could hear sound again. Just like normal. So I tested it by switching power off, then on again. No relay click, regular or delayed.

Does that info help? I thought AK guys were smart and would have encountered this before? Any suggestions on what's failing?
 
After about 15 minutes of dead sound I switched it off. Then switched it on and the relay clicked after a few seconds and its making sound again like normal. So this issue appears intermittent. But it renders it pretty much useless, unless I can repair it. It appears a part is failing and still has limited life but on the way out. Does that help with diagnosis?
 
you would first be looking at the dc offsets or otherwise known as dc balance from the amplifiers output . needs to be close to zero volts .
the protection circuit monitors these voltages and if too high wont engage the relay to the speakers ..if dc offsets are good it very likely the fault is in the protect circuit .
 
I don't know what that means.

The rely click isn't happening most the time. If it does, it shortly clicks itself off, with a very brief 1 second burst of static in the left earphone. Then its dead sound. But the face is lighting up. So I think that means the power is ok, right? The fuse isn't smoked. There's no strange burning smell. No sparks. Nothing looks different inside that I can see. I had this plugged into a power strip with some surge protection capabilities, I don't know if that has anything to do with it. Just providing more detail.
 
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it could be a power supply issue ..needs looking at by someone that understands these things and has the correct tools .
there are ak members that do such a thing . maybe someone is near to you that can have a look for you .
 
If none of these bitches step up, what part would you suggest I try replacing first? Does that question make sense?
 
best if someone with knowledge looks at it for you ..hopefully someone will turn up soon .. its been a bit slow lately around here .
 
version2 said:
If none of these bitches step up, what part would you suggest I try replacing first? Does that question make sense?
Click to expand...

Classy response. Welcome to AK and Good luck!
 
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Dude, take it to a shop. Could be many many things wrong with it, so you can't just throw parts at it. You should hope that it is not an STK unit.
You might take off the bottom panel and have a look at the back of the circuit board for burnt parts.
Good luck.
 
I removed the back cover. Very easy to do with the R-500. Carefully viewed the back of the board with 3.0 reading glasses, and flashlight. Nothing looks smoked or damaged. I don't think its the STK replacement. If the part was defective, or the techie botched the install, it would have given me problems much sooner. What's the MTBF for a repair like that? I'm guessing once it goes in correctly its pretty much good as new, if not better for 10 years.

How do I identify the capacitor for protection circuit that needs to be replaced? Can you explain that in a idiot proof way with a pic or part number or something. I don't mind replacing a few old parts with new parts. Parts are easy to find on ebay for this receiver to my understanding.

If I don't fix it, then I have to buy the new RS500 which is $400. Probably should do that anyway, even if I fix this old one.
 
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version2 said:
IHow do I identify the capacitor for protection circuit that needs to be replaced? Can you explain that in a idiot proof way with a pic or part number or something I can't **** up.
Click to expand...

You need to download the service manual.
http://akdatabase.org/AKview/displayimage.php?album=3&pos=213

That's the best way for you to learn where the components are. The PCB layouts start on page 12, the schematic is on page 14 & 15, the parts list starts on page 24.

Cheers,
James
 
Studying PDF service manual, I was able to identify the DC offset voltage adjust, for L and R. Can I tweak those to "adjust" them? The capacitor parts list is not understandable to layman. How do you identify the capacitor for circuit protection? On the PCB diagram every part that begins with the letter C is a capacitor, correct? There are numerous around the DC offset voltage adjust. Any way to make sense of that?
 
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Its up an running as of today, after sitting unplugged for approx. 6 weeks. I plugged it in this morning to check before I boxed it up and put it in the closet, and its been working as normal. Relay click after 5 seconds, with normal sound. It repaired itself?
 
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