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Pioneer SX-780 Repair help

Larry you were right, sound clears up in mono but is very weak with no amplification or power. Switch on stereo and it distorts. It wasn't obvious before because I wasn't getting any reception. Cleaning the points and working the tuner back and forth solved that issue, all the stations are coming in now. I did notice even in mono the stereo led still works and lights up as if I'm in stereo mode.

I didn't find any blue Sanyo caps. From another post I read are you referring to C37, C38, C40?

There is also C74 and C36 that are clear body, metallic appearance which look dead.

Could you please list which problematic caps I should change and suitable replacements especially for C74, C36?

I replaced R28 & R29 as they tested open in circuit. The legs on the old ones were brittle and broke right off. I tested what was left of them out of circuit and was surprised they were both in spec.

Q1 & Q2 voltages are good.
Q10 = B: 0v, C: 0v, E: 0v,
Q7= B: 8v, C: 5v, E: 7v
Q8= B: 8v, C: 5v, E: 7v

PA1001-A
Pin 1: 12.60v
Pin 2: 3.2v
Pin 3: 5.5v
Pin 4: 8v
Pin 5: 8v
Pin 6: 6v
Pin 7: 0v
Pin 8: 2.9v
Pin 9: 0.8v
Pin 10: 2.4v
Pin 11: 2.4v
Pin 12: 2.5v
Pin 13: 2.5v
Pin 14: 2.5v
Pin 15: 3.5v
Pin 16: 0.04v

HA1197
Pin 1: 0v
Pin 2: 0v
Pin 3: 0v
Pin 4: 13v
Pin 5: 13v
Pin 6: 0v
Pin 7: 0v
Pin 8: 3v
Pin 9: 9.5v
Pin 10: 0v
Pin 11: 13v
Pin 12: 1.5v
Pin 13: 0.7v
Pin 14: 1.5v
Pin 15: 0v
Pin 16: 0v

HA1201
Pin 1: 0v
Pin 2: 1.5v
Pin 3: 0v
Pin 4: 1.5v
Pin 5: 11.86v
Pin 6: 12.98v
Pin 7: 13v
Pin 8: 8v

PA3001-A
Pin 1: 1.97v
Pin 2: 1.97v
Pin 3: 1.97v
Pin 4: 0v
Pin 5: 0v
Pin 6: 5.7v
Pin 7: 5.9v
Pin 8: 5.6v
Pin 9: 5.6v
Pin 10: 5.6v
Pin 11: 12.7v
Pin 12: 3.5v
Pin 13: 0v
Pin 14: 0v
Pin 15: 5v
Pin 16: 3.6v

Hopefully someone can decipher all that data!
Thanks
 
The light (no matter whether in MONO or Stereo.) It's just indicating that the signal is stereo and can be set to stereo. It will still indicate with MONO Set. C74 and C36, if clear and have an end that looks like a light lens, are styrene caps. These aren't replaced as they don't have a tendency to go bad. They ARE highly sensitive to heat from an iron, and heat sinks (Hemostat's for us medical personnel or roach clips for the users, work well)are required on the leads to replace.
These

As for the rest of the caps. Usually anything UNDER 4.7uf will get a film cap. (WIMA MKS type) provided there is physical room for them. There should be some .47uf, .33uf, and .22uf electrolytics on the tuner board. Replace them. IIRC on the end opposite from the power supply there are some small value (<4.7uf) caps. Wima's here too. Otherwise Nichicon UPW/UHE for power supply, and UKL for signal path. BEEN almost a decade since I've had mine open.

POST a couple pictures of the main board and the tuner board.
 
I removed all capacitors and tested them for capacitance and ESR. There was only two small 1uf that had high ESR. I replaced everything - no change.
Q7, Q8, Q10 all passed diode test and voltages are good as far as I can tell. I might replace just to rule them out.
Im half way done testing all the resistors, everything good so far.
Can we suspect a bad chip at this point?
 
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FM works great now! It was Q29, Q28 that were replaced with J113 causing the problem. I had a spare 2SK34 pulled from the board, I decided to reinstall it as a test in Q29 and the problem went away. A BIG thanks to everybody who helped out and stuck with me on this one! Cheers :beerchug:
 
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