SA-8500 driving me insane!

slayer44

Well-Known Member
At my wits end here. So a while back my 8500 just stopped working. No fizzle, no sound drop off...just relay off. So I recapped the switch and power amp assy. I put in ALL new transistors while I had it all apart. I have done at least 20 amps before this so I know I got them all in right. I checked and re-checked. Put it back together and worked awesome for about six hours all the while monitoring the outputs heat. My idle and offset were dialed in perfectly IAW the manual. No DC from the speaker terms. I checked ALL the voltages at all pins and trannies and within spec. Still no relay. Changed the trannies and caps in relay circuit, nothing. I am out of troubleshooting steps that appear in these forums, so any guidance would be greatly appreciated. I will post my voltages soon as I neaten up my desperate hen scratching. Thanks.
 
Had to restart my phone...keyboard was getting funky. I have no relay click with the preout jumpers in or out. Forgot to mention, before the relay quit altogether, it would click on and off repeatedly every three seconds or so which led me to believe weak trannies might be the culprit. Also, do the polyester caps degrade over the years?have never changed those so no idea and there is a ton of them in this amp. Any ideas are welcome.
 
Have tried cleaning or replacing the relay itself? have you measured DC Just at the speaker terminals or in the amp itself? If the relay won't engage, of course you won't get DC at the terminals, as the relay is there to block DC if it sees too much.
 
BBerkom, I did think about that. It did feel like a mechanical failure the way it would randomly cycle. I checked the resistance of the coil and got some, so it isnt open. The contacts look spotless, so no carbon buildup. I am not getting voltage at the relay coil so eliminated that avenue. Thank for the idea though...keep em coming!
 
Sc1845's...I got the legs right. In my notes the 1313 are BCE, 1845s are ECB. I double checked just now. I think you may have helped me. I just checked a 992 I used for Q9 and I had two goddamned legs touching!. Sorry for cussing but damn my eyesight sometimes. Got it out of protection and waiting the ten min to check offset/idle again. Its always human error isn't it?...be right back.
 
Yeah right!...its aggravating though. I thank you reminding to recheck my work. I knew it must have been something dumb I did. I think its time to finally get my first pair of glasses...been putting it off. I will report my amps findings after I get it adjusted for the benefit of others...In other words, get your eyes checked!
 
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