I got this one from a Craigslister, "just a little noisy on one channel". Yeah, right!
Anywho, it was cracking an popping something fierce on one channel. Even going into protection from time to time. The guy said he pulled the jumpers and it didn't go away, when actually he pulled one jumper (the one on the good channel).
That problem turned out to be a bad JFET, Q3 on the preamp board. I didn't have the exact replacement, so I replaced it and Q4 with SK3112, turned 180 so the pins were correct. I recapped the board while I had it out, and did the the usual cleaning / de-oxiting.
Next problem was snapping through the speakers when turning the unit off.
I replaced all of the electrolytics on the protection board. Problem solved.
Final problem was snapping in one channel when turning on the tone controls.
I replaced all of the electrolytics on the board, problem still there.
I scratched my head for awhile, checked voltages and such, even floated a thread here.
I had thought of possible bad tantalum caps, but I wasn't sure if they even went bad with age. Sure enough, got a suggestion about them, so out they came, and I had to rob some out of an SX 850, just to try it.
Whoo Hooo!! Perfect! What a sweet receiver.
Now that it was working proper, I set the bias and the dc offset to spec, cleaned/de-oxited the rest of the controls and gave 'er a bath.
As fond as I am of the Sansui G-series, I must say that these Pioneers are just about the most attractive receivers ever made.
Gentlemen, behold!
Anywho, it was cracking an popping something fierce on one channel. Even going into protection from time to time. The guy said he pulled the jumpers and it didn't go away, when actually he pulled one jumper (the one on the good channel).
That problem turned out to be a bad JFET, Q3 on the preamp board. I didn't have the exact replacement, so I replaced it and Q4 with SK3112, turned 180 so the pins were correct. I recapped the board while I had it out, and did the the usual cleaning / de-oxiting.
Next problem was snapping through the speakers when turning the unit off.
I replaced all of the electrolytics on the protection board. Problem solved.
Final problem was snapping in one channel when turning on the tone controls.
I replaced all of the electrolytics on the board, problem still there.
I scratched my head for awhile, checked voltages and such, even floated a thread here.
I had thought of possible bad tantalum caps, but I wasn't sure if they even went bad with age. Sure enough, got a suggestion about them, so out they came, and I had to rob some out of an SX 850, just to try it.
Whoo Hooo!! Perfect! What a sweet receiver.
Now that it was working proper, I set the bias and the dc offset to spec, cleaned/de-oxited the rest of the controls and gave 'er a bath.
As fond as I am of the Sansui G-series, I must say that these Pioneers are just about the most attractive receivers ever made.
Gentlemen, behold!
