Pioneer SX-636 30V on left output

c 29 and c30 0.012uf 50v CQMA 123K 50 are MYLAR caps and are not electrolytics and are NOT replaced. THAT is WHY they are not ON MY LIST!!
http://www.audiokarma.org/forums/in...-sx-636-rushing-sound-on-left-channel.517531/

LOOK at the SX-636 parts list, only the CEA, any CEB, CEANL, CSSA, CSZA caps are electrolytic and need to be replaced.

CSSA, CSZA, CEANL are all replaced by low leakage Nichicon UKL caps - see my "rules of thumb".

Caps of all these types that are 0.1uf to 1.0uf are replaced by ECQ type film caps. And never need replacing again. No deterioration modes like electrolytics. SMH
nice thread! due to the way i think things i used my MS paint skills and color coded all the caps. i dont think i missed any.
upload_2016-12-24_12-19-55.png
gonna start adding the caps and trannys to my mouser list.
Do the trannys need to be gain matched?
 
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i used my MS paint skills and color coded all the caps.

Nice job on the color-coding to help everyone quickly see what you're talking about.

Do the trannys need to be gain matched?

Being a relative newbie, I don't know the precise answer to this. However, when you look at the quantity pricing for the replacements for the 2SA726 and the 2SC1344 transistors, the practical answer might be easier. You can get 10 KSA992's or KSC1845's for under $2.00 and 100 of either for $6. This approach won't be perfect for every budget, but having 90 or so extras lying around for your next Pioneer project and getting perfectly-matched pairs is pretty cheap.
 
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so far all ive gotten in C29 and C30 tantalum are being swapped out with film caps.

I have a lot of respect for MTF and I've based a lot of my learning on the time and experience he's shared here. Bb, if you are asking the question because your board seems to have tantalums at C29 and C30, then you very well may want to replace them. I think it would be unusual for those low-capacitance caps to be tantalums, but just in case they are and you need replacements:

  • Are they in the audio path? Then look for metalized polypropylene, polypropylene, metalized polyester, or polyester film caps (kinda in that order, to find the best you're willing to pay that price for) to replace them. Panasonic caps aren't the only ones that will work there.
  • Are they not in the audio path? Then mostly any film cap should do (remember I'm just an amateur; someone smarter than me will jump in here; just wait for them before ordering). I like MLCC caps for some replacements, so just look at the characteristics of the film, stacked ceramics, and ceramics that match.

i would like to redo it with different caps for power and audio paths but im not good at following schematics :( the tone amp board has a few low leakage caps on it so i need to take note of those and figure out what to replace them with. anyone mind telling me the audio path and power supply caps on the tone amp so i can go through and mark them?

MTF has shared his view on replacements, so that's a great starting place. If you have your own reasons for going further than that or doing differently, then rock on and have fun. And please share with us your whys, the whats, and the eventual how-it-turned-outs.

The following is not THE audio path, but rather a starting point. From the very little I know, this is part of the path the audio signal follows in the RIAA equalization circuit:

SX-636 RIAA circuit audio path.png

Would others chime in here and help point out the bits I'm missing and why they are part of the signal path, please? Bb is asking for help and I'm really, really interested in learning more.
 
that's a pretty good audio path, there is additional feedback audio through r19, r27,c17,c15 r25
the components r27,c17,c15 r25 are RIAA network that set the equalization curve.

IF C29 and C30 are NOT the big green lozenge type CQMA mylar capacitors, and instead little bitty tantalums were swapped in by the factory, yes replace them. read the cap sections here: http://audiokarma.org/forums/index.php?threads/pioneer-tuning-fork-service-guide.249745/

In the circuit above, gain matching of the transistors is NOT needed, in fact it would have no discernible effect. that means not only ears, but meters and scopes and distortion analyzers too.

My recommendations on caps differentiate between low leakage and "general" caps.
NOW we're getting into personal opinions here with "signal path caps" and particular brands etc.
Todays general caps are far better than audio caps of that era.
IN MY OPINION Todays audio caps are more marketing hype than PROVABLE, explainable measurable physical differences between them and the good general caps (panasonic fc,fm &, nichicon upw, uhe).

The only one I acknowledged that it is slightly better is the SilMic caps, and that is a slightly better resistance to mechanical vibration modulating itself upon the signal.
Sil = silk as in chopped up silk threads included in the separators, stiffening them a bit
mic as in microphonics
Quite frankly, an amp in that sound pressure level environment, you'd have a hard time measuring the difference - BUT IT'S THERE!! So I acknowledge it.
 
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Another audio signal path is through C11, it provides a short circuit for AC. It increase the AC gain of the common emitter amplifier stage. without it, the AC gain is substantially lower, as there would be much more local negative feedback.
C3 also does the similar operation of providing a AC short to the signal.
 
My recommendations on caps differentiate between low leakage and "general" caps.

Help me understand something, please. I've read several places here that audio path caps should be as low leakage as possible. Other places state stacked metalized polypropylene and polyester caps have no leakage. That would make them a better fit for audio path, even than UKL Nichicon electrolytics, when available. Right? Or is there another factor keeping UKL at the top of the list?
 
A film cap is far better than a ecap in terms of leakage and other parameters. ecaps are used because they provide much higher C for the same size of a film and are cheaper for the same capacity.
 
that's a pretty good audio path, there is additional feedback audio through r19, r27,c17,c15 r25
the components r27,c17,c15 r25 are RIAA network that set the equalization curve.

So, is this more accurate?

SX-636 RIAA circuit audio path.png
 
Another audio signal path is through C11, it provides a short circuit for AC. It increase the AC gain of the common emitter amplifier stage. without it, the AC gain is substantially lower, as there would be much more local negative feedback.
C3 also does the similar operation of providing a AC short to the signal.

Ok, so should C11 and C3 be low leakage caps?
 
Yes, that is what I would recommend or better yet film if you can get them to fit. look for 5mm lead spacing films.
I see you circled the RIAA feedback network. One usually uses tight tolerance components for that part, 1% or better R's. Harder and more expensive to get tight tolerance C's
 
Ok, so this is a better picture of the audio path in the SX-636 EQ amp (RIAA equalization for phono) circuit:

SX-636 RIAA circuit audio path.png
 
You should NOT be effing around with the RIAA network - there are NO components that need replacement in it.
Chances are you will NOT get the values you need, they were most likely special ordered when manufactured.

C11's being low leakage is useless because there is a 27k ohm resistor across it, and that will swamp out any leakage.
C13 is an output coupling cap. Outputs have large signals present, so any noise contribution it could make would be far lower
than any noise in the quietest of audio signals.

Low leakage caps are only effective in certain sensitive locations. We ASSUME that CSSA and CZSA cap locations are low
leakage, because that is a characteristic of those caps WHEN OPERATING CORRECTLY. To TRUELY know if CSSA and CZSA
caps in a particular circuit position NEED to be low leakage, the circuit has to be extensively reverse engineered. To see WHAT
requirements drove their selection: size? cost? prestige? leakage? capacitance? many other factors?
 
You should NOT be effing around with the RIAA network
they were most likely special ordered when manufactured.

not sure why were yabbing on about the phono board...all i planned to do was replace the electrolytics. but even with that said, nothing looks to be "special". all parts i could get from mouser. lets just say i were to replace R25 or R27 because lets say it had its ass blown to the moon and beyond. i would get some 1%-0.1% tolerance replacements anyway just because its such a sensitive circuit. but i would bet the factory's are most likely 5% anyway.
 
lets just say i were to replace R25 or R27 because lets say it had its ass blown to the moon and beyond. i would get some 1%-0.1% tolerance replacements anyway just because its such a sensitive circuit.

The experience I had, in all three Pioneers where I replaced 100% of the components in the phono circuit with 1% or better tolerance modern parts, was subjectively-better audio performance. I'm pretty sure the quality and precision of the parts I put in were superior (I.e. Closer to the schematic's intended value) to the factory ones. There was no absolute reason to replace them; I did it for fun and learning and to apply the learning I had in building my own tube-based phono-stage-only preamp. It was fun, it fit easily in my budget, and it gave me lots of practice searching for parts, comparing data sheets, and searching through AK for related advice, opinion and experience.
 
Sanyo D313. need a replacement.
Why did pioneer and realistic use that transistor in every receiver they made in the 70's?
EDIT: 512-KSC2073TU?
 
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Sanyo D313. need a replacement.
Why did pioneer and realistic use that transistor in every receiver they made in the 70's?
EDIT: 512-KSC2073TU?

Can't just say the D313, gotta say WHERE in the unit it is. We can GUESS, research that model to see if only one D313 in unit - but you KNOW and ain't tellin...
I usually don't have time lately to do that type of research. So you don't hear from me.

The other 2073's in mouser with the gobbledygook numbers are special lead configurations, usually that means they were CUT, which we DON'T need...
so yes, as far as mouser numbers 512-ksc2073tu but I don't know if THAT transistor is appropriate for the position.
IF it is the low voltage (13v) power supply (mostly) for the tuner - yes.

But it also could be the "high" voltage power supply or even the output transistors, and if so, no.
 
Can't just say the D313, gotta say WHERE in the unit it is. We can GUESS, research that model to see if only one D313 in unit - but you KNOW and ain't tellin...
I usually don't have time lately to do that type of research. So you don't hear from me.

The other 2073's in mouser with the gobbledygook numbers are special lead configurations, usually that means they were CUT, which we DON'T need...
so yes, as far as mouser numbers 512-ksc2073tu but I don't know if THAT transistor is appropriate for the position.
IF it is the low voltage (13v) power supply (mostly) for the tuner - yes.

But it also could be the "high" voltage power supply or even the output transistors, and if so, no.
It's a single 313 on the power supply. Not sure the voltage I haven't checked yet
EDIT: Looks like 13.5V
 
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ok so on the power supply,
D313 - 512-KSC2073TU
D234 - 512-KSC2073TU?
C945 - 512-KSC1845FTA?

Pre
C1344 - 512-KSC1845FTA
A726 - A992
 
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ok so on the power supply,
D313 - 512-KSC2073TU
D234 - 512-KSC2073TU?
C945 - 512-KSC1845FTA?

Pre
C1344 - 512-KSC1845FTA
A726 - A992
Sooo, will those transistors work to replace the old ones?
The WZ-140 Zener diode on the power supply, i would guess its a 14V zener?
 
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The WZ-140 Zener diode on the power supply, i would guess its a 14V zener?

Yes, the WZ-140 is a 14V Zener with 0.5W dissipation in a DO-35 package. I can't find my saved-aside PDF of an old cross reference guide and all my 1970's semiconductor cross-references are in storage (I'm in-between moves).
 
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