Back to it! A Pioneer SA-9500 that Ron ought to recognize...

jbeckva

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LOL

Well heck guys... listening to it now. Not too shabby... Not a WOPL, but still pretty darn good.

Kelly - since this showed as intermittent, it's best to keep stressing and testing for a few days... :thumbright::violent1:
 
Elite-ist

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That seemed almost too easy for you, Jerry. I bet for an integrated amplifier, in that power class and vintage, it would be hard to best. Although I sold my Pioneer SA 9500II, it was such a good-sounding integrated amplifier it was hard to let go of it. I doubled my money on it, so I wasn't too disappointed. I was beginning to mature and realized I couldn't hold onto everything.





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Nando.
 
Z

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jbeckva said:
LOL

Well heck guys... listening to it now. Not too shabby... Not a WOPL, but still pretty darn good.

Kelly - since this showed as intermittent, it's best to keep stressing and testing for a few days... :thumbright::violent1:
Click to expand...

great news jerry, stress and test all you want, didnt buy it to look at, bought it to blast it!
 
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zkman2002 said:
great news jerry, stress and test all you want, didnt buy it to look at, bought it to blast it!
Click to expand...
Well ugh, I am noticing something but as I recall not exactly what you initially described. The offset adjustment did help with it not going in and out of protection (kicking the relay off) so we are making progress. Now what I am hearing is every now and then noise and static. The semi-good news is it does not appear to be an issue with the power amp section, but rather in the preamp. Could be a deoxit job away from fixing, but "them's" a lot of pots and switches to first get to then douche out. But first I need to do the same isolation test in reverse - using the power amp section separated (driven by my own pre), and seeing if the issue follows or disappears. If it follows, then it's "there" or possibly something in the power supply (need to be watching the supply voltages). If not, preamp section is suspect. And off to deoxit land we go... hehe.

More this weekend when I get more time to take a crack at it...
 
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jbeckva said:
Well ugh, I am noticing something but as I recall not exactly what you initially described. The offset adjustment did help with it not going in and out of protection (kicking the relay off) so we are making progress. Now what I am hearing is every now and then noise and static. The semi-good news is it does not appear to be an issue with the power amp section, but rather in the preamp. Could be a deoxit job away from fixing, but "them's" a lot of pots and switches to first get to then douche out. But first I need to do the same isolation test in reverse - using the power amp section separated (driven by my own pre), and seeing if the issue follows or disappears. If it follows, then it's "there" or possibly something in the power supply (need to be watching the supply voltages). If not, preamp section is suspect. And off to deoxit land we go... hehe.

More this weekend when I get more time to take a crack at it...
Click to expand...
Couple years back Jer, I had one of those with the occasional low level bzzzzzz that would come and go very intermittently on a PL700B that Johan asked me to diagnose and fix. It turned out to be a marginal TO-3 socket on the backplane. The electrical arcing noise would radiate everywhere and make it show up on both channel outputs. Replacing every socket and rewiring the backplane fixed it for good. Johan gave me a CD that would bring it out occasionally in a certain section of one cut on the CD. Just the right sequence of loud sounds to produce the output current to bring it out...

Good luck, these are not easy to find and fix.
 
orange

orange

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Good observation, I wonder if it proves to be prophetic.
 
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Ok, so after setting it to separated and plugging a pre into the power amp in, I hear no issues.. fritzes.. etc. That means the preamp section and likely the associated switches. "Easy/Obvious" step first which will be hitting it hard and thorough with deoxit. Then we start looking for components.

My prime suspect would be the fets on the input stage. Joe.. is it a fact or not that over time, fets do degrade and introduce spurious noise into the circuit? I remember we had FET switches between the switching matrix and measurement sections back in the Nav days, and we went through quite a bit of them when the measurement path would not calibrate properly...

Hmmm.. maybe with the separate/combined switch first.. :scratch:
 
orange

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First of all, maybe we should bring everyone up to speed here...this is the block schematic for either channel of this model.
SA9500 block schema.jpg​
 
orange

orange

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Now...if you say that's fine then where do we look next?

The entire service manual is available on hifiengine.com FREE with membership, as usual.
 
jbeckva

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Steven, the first thing I did (year ago) was to get the skeezer lol.. But thanks!!.. :hello1:

Waitin' for Joe to clue me in on the FET's and noise.. do they degrade and introduce noise over time?
 
laatsch55

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A BJT input pair does....FET's are not bullet proof, so yeah I think they would get noisy over time..
 
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laatsch55 said:
Like any other semiconductor Jer, they're gonna degrade...
Click to expand...
Semiconductors usually fail due to overstress of some form or from mechanical problems associated with heating and cooling cycles affecting the bond wire integrity. Or from initial fab process problems that take years to manifest (failure in time).

Properly made semiconductors that are not overstressed should theoretically last forever. Seldom true.
 
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