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Small Pioneer SX-636 problem...

Ok, I hope the rest are being edited in, from the quote it looks like you caught the post as I was entering it in,
I was expecting 4 more critical measurements:

base of Q7 (red dmm lead) to base of Q9 (black dmm lead) should be about 2.4 volts
base of Q10 (red dmm lead) to base of Q8 (black dmm lead) should be about 2.4 volts

emitter of Q7 (red dmm lead) to emitter of Q9 (black dmm lead) should be about 1.2 volts
emitter of Q10 (red dmm lead) to emitter of Q8 (black dmm lead) should be about 1.2 volts

the voltage 1 and voltage 2 readings for both channels is fine, and providing me food for thought...

and the millivolts do matter!!
 
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Okay, here is the base voltages:

Q7 and Q9 base: 2.443v
Q8 and Q10 base: 2.383v

Q7 and Q9 emitter: 1.283v
Q8 and Q10 emitter: 1.226v
 
Well, we are getting somewhere. With the diodes shorted, I cannot get any idle current. Should I put in 100 ohm resistors like the 525?
 
With the diodes shorted ( a slightly unexpected jump ahead, but my phrasing is partially at fault) re measure all the base and emitter voltages, then try increasing the resistance and watch the idle current.

IF you can hit the indicated current, fine, otherwise read the resistance and voltages and current (by a voltage reading) at maximum to see where we are at and how short of the goal we are.

The pot IS paralleled to a 200 ohm resistor, which affects any mods to get it working.....
 
Here are the voltages at zero ohms:

Q7 and Q9 base: 2.371v
Q8 and Q10 base: 2.376v

Q7 and Q9 emitter: 1.170v
Q8 and Q10 emitter: 1.175v

Turning the pot all the way up gets only 0.1mv of current, which is why I was asking if I should put a 100 ohm resistor in the place of the diode.
 
Hooray, it works! I put in two 100 ohm resistors, one for each channel, powered up on the DBT (defiantly) and was able to set it to 20mv solid with the pot turned about halfway, no problems. Turned it back down to zero ohms and took it off the DBT, then powered it up, carefully watching the idle current. No problems again, so I set the idle current and have had it playing for about half-hour and the sound is so sweet! I just checked the current again and it is still 20-20.5mv.

Thank you once again, Mark, for all that you do.

Is there any thing else you would like to recommend that I do?
 
Sorry for bringing up a old thread, but I am planning on recapping the tuner board on this thing along with my SX-890, as almost all the caps on it are the blue Sanyo caps. It sounds okay right now, but preventive maintenance never hurt.

Here is the list I put together:

AWE-046-0 C18: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWE-046-0 C20: 10uF 16v CEA: 647-UPW1E100MDD6 10uF 25v
AWE-046-0 C21: .47uF 50v CEA: 667-ECQ-E1474KF .47uF 100v
AWE-046-0 C25: 1uF 50v CEA: 647-UPW1H010MDD 1uF 50v
AWE-046-0 C28: 100uF 16v CEA: 647-UPW1V101MPD 100uF 35v
AWE-046-0 C32: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWE-046-0 C33: 47uF 6.8v CEA: 647-UPW1A470MDD6 47uF 10v
AWE-046-0 C36: .1uF 25v CSSA: 667-ECQ-V1H104JL5 .1uF 50v
AWE-046-0 C39: 10uF 16v CEA: 647-UPW1E100MDD6 10uF 25v
AWE-046-0 C44: 10uF 16v CEA: 647-UPW1E100MDD6 10uF 25v
AWE-046-0 C48: .33uF 10v CSSA: 598-DSF050J334 .33uF 50v
AWE-046-0 C49: 1uF 10v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWE-046-0 C50: .47uF 10v CSSA: 667-ECQ-E1474KF .47uF 100v
AWE-046-0 C59: .33uF 25v CSSA: 598-DSF050J334 .33uF 50v
AWE-046-0 C60: .33uF 25v CSSA: 598-DSF050J334 .33uF 50v
AWE-046-0 C61: 220uF 16v CEA: 647-UPW1E221MPD1TD 220uF 25v

All of them are in stock, I just want to confirm that I have the correct substitutes for these.
 
mattsd said:
Sorry for bringing up a old thread, but I am planning on recapping the tuner board on this thing along with my SX-890, as almost all the caps on it are the blue Sanyo caps. It sounds okay right now, but preventive maintenance never hurt.

Here is the list I put together:

AWE-046-0 C18: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWE-046-0 C20: 10uF 16v CEA: 647-UPW1E100MDD6 10uF 25v
AWE-046-0 C21: .47uF 50v CEA: 667-ECQ-E1474KF .47uF 100v
AWE-046-0 C25: 1uF 50v CEA: 647-UPW1H010MDD 1uF 50v
AWE-046-0 C28: 100uF 16v CEA: 647-UPW1V101MPD 100uF 35v
AWE-046-0 C32: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
AWE-046-0 C33: 47uF 6.8v CEA: 647-UPW1A470MDD6 47uF 10v
AWE-046-0 C36: .1uF 25v CSSA: 667-ECQ-V1H104JL5 .1uF 50v
AWE-046-0 C39: 10uF 16v CEA: 647-UPW1E100MDD6 10uF 25v
AWE-046-0 C44: 10uF 16v CEA: 647-UPW1E100MDD6 10uF 25v
AWE-046-0 C48: .33uF 10v CSSA: 598-DSF050J334 .33uF 50v
AWE-046-0 C49: 1uF 10v CSSA: 647-UKL1H010KDDANA 1uF 50v
AWE-046-0 C50: .47uF 10v CSSA: 667-ECQ-E1474KF .47uF 100v
AWE-046-0 C59: .33uF 25v CSSA: 598-DSF050J334 .33uF 50v
AWE-046-0 C60: .33uF 25v CSSA: 598-DSF050J334 .33uF 50v
AWE-046-0 C61: 220uF 16v CEA: 647-UPW1E221MPD1TD 220uF 25v

All of them are in stock, I just want to confirm that I have the correct substitutes for these.
Click to expand...

So confirmed, I have gone over it line by line. Using the service manual.

C48, C49 & C50 may affect the stereo decoder a bit. But you may get away without needing an alignment, IF it hasn't been touched since the factory.

Nowadays the pin 18 (ic pin 10) test point can be set (vr1) with a frequency counter to 4 x 19khz = 76 khz without a stereo broadcast being received.
 
It has not been touched, have not needed to as it is currently spot on for alignment.

Thanks, Mark! :thmbsp:
 
mattsd said:
Hooray, it works! I put in two 100 ohm resistors, one for each channel, powered up on the DBT (defiantly) and was able to set it to 20mv solid with the pot turned about halfway, no problems. Turned it back down to zero ohms and took it off the DBT, then powered it up, carefully watching the idle current. No problems again, so I set the idle current and have had it playing for about half-hour and the sound is so sweet! I just checked the current again and it is still 20-20.5mv.

Thank you once again, Mark, for all that you do.

Is there any thing else you would like to recommend that I do?
Click to expand...

Talk about a resurrection, a thread from 2010...Used this trick by mattsd, I was having the same issue with a 636 in for repair.The 100 ohm resistors worked like a charm.
Thanks Matt and Mark!
 
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