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Pioneer SX-636 30V on left output

well it shouldn't really affect it to a great extent with the design . i know single supply amps like cap coupled ones the dc balance and bias can affect each other greatly .
 
Finally have some good news to report. After replacing R28, R30 (.5 ohm 5w ) and R36 (10 1/2 w) My R output came under control to 19 mV DC.

Learned a few things about things faulting in circuit even tho they measure correctly out of circuit.
 
testing in circuit is the way to go ... not enough power from multi-meters to test for real ...its a no go or anyone's guess ...
 
After playing the 636 for a few hours i quickly found out. its REALLY sensitive on the low end, like 60Hz and below. i have the bass knob flat and the low end it on par with my Fisher's 63Hz slider at around +6dB. maybe thats why people say these 70's units sound so warm because there sensitive to the low end. i love that i dont even need an EQ with this. only the treble knob up 2 steps.
 
got the rectifier built for if i decide to pop an LED in the dial pointer. if not i guess i have a 1A rectifier for something else
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1000uF is probably a bit big for a single LED on a full wave bridge...but whatever. i think it looks neat all together like that.
 
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First, I know about zero about electronics and magical smoke inside electronics parts, so take the following with that in mind, please:

1. The (capacitance) size of the reservoir cap (the first one past the rectifier) will have an effect on the current inrush when power is first applied. So, a huge reservoir cap immediately will draw a lot of current in quickly to "fill" that cap initially. I don't know how that will effect this downstream-from-the-initial-power-supply circuit, but something to research more.

2. My understanding of power supply circuits is you really need either a RC filter or a LC filter just beyond the rectifier and the reservoir capacitor so the output is smooth (little or no ripple). So, you should add a resistor (to make a RC filter) or an inductor (to make a LC filter) in series with the positive output of the reservoir cap and add a smaller filter cap. Why? I don't know, but just the filter cap itself is rare (or wrong, maybe). http://www.learnabout-electronics.org/PSU/psu12.php

I think your idea here is really, really good. There are lots of convert-AC-powered-indicator-lamp-to-LED opportunities here on AK and a simple, small, cheap keep-the-LED-from-flickering solution would help numerous people.
 
Yes im aware of the larger caps inrush current. thats why my A-1100 (pair of 8200uF filters) dim my lights on power up. i think an SX-1280 filter caps pull 150A right at power up. thats enough to knock you flat on your ass real quick!
 
Bassblaster said:
Yes im aware of the larger caps inrush current. thats why my A-1100 (pair of 8200uF filters) dim my lights on power up. i think an SX-1280 filter caps pull 150A right at power up. thats enough to knock you flat on your ass real quick!
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The house fuses or circuit breakers feeding whatever AC socket would kick in, wouldn't they, if any device drew more than the 10 or 20 amps they (the house breaker or fuse) were rated for. I think... unless the transient draw was too short-lived to trip the breaker.

Another way of looking at it would be the rectifier diodes or bridge would have to be capable of that much current draw, albeit peak instead of recurring. I don't totally understand all the the secondary specs on diodes and bridges yet, but I think 150 amps is too much for most stereo gear rectifiers.
 
dlucy said:
The house fuses or circuit breakers feeding whatever AC socket would kick in, wouldn't they, if any device drew more than the 10 or 20 amps they (the house breaker or fuse) were rated for. I think... unless the transient draw was too short-lived to trip the breaker.
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that really high current is "surge current" not "continuous current" so it wont pop any fuses, beakers or diodes.
for example. standard house breaker in the US is 15A continuous meaning they can take 100A+ very briefly. just like a large cap charging up.
example 2. a 1N4004 diode can take 1A continuous and 20A surge. a 1N5404 and take 3A continuous and 200A surge.

dlucy said:
Another way of looking at it would be the rectifier diodes or bridge would have to be capable of that much current draw, albeit peak instead of recurring. I don't totally understand all the the secondary specs on diodes and bridges yet, but I think 150 amps is too much for most stereo gear rectifiers
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Nope. for massive caps that kind up inrush current is normal. but because its very brief it wont pop any thing in circuit.
if i can find the page that said 150A at startup ill edit it in here.
EDIT: not was i was looking for but close enough
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i got about 200 records about a week ago and i can confirm my TT's output is WAYYYYY to high for the built in preamp. its nothing but pure distortion. turning the volume to the first notch drives the amp to audible clipping. so for now i just have it running into the 2nd tape monitor. doesnt sound bad just have to turn the bass knob to the max and its still a bit weak. im thinking about adding some dropping resistors to the output in my TT. what do you think a good value would be?
 
Bassblaster said:
i got about 200 records about a week ago and i can confirm my TT's output is WAYYYYY to high for the built in preamp.
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That is odd. The phono circuit in a modern receiver is expecting about 5mV from an unamplified MM cartridge. That's actually the highest voltage of typical cartridges as MC cartridges are much lower.

Is your TT one of the newer ones with a built in preamp turning its internal 5mV cartridge output into line level 1V output? That would match your symptoms. If so running it into the TAPE 2 or AUX would be one option but that would bypass your SX's nice RIAA EQ phono preamp.
 
dlucy said:
That is odd. The phono circuit in a modern receiver is expecting about 5mV from an unamplified MM cartridge. That's actually the highest voltage of typical cartridges as MC cartridges are much lower.

Is your TT one of the newer ones with a built in preamp turning its internal 5mV cartridge output into line level 1V output? That would match your symptoms. If so running it into the TAPE 2 or AUX would be one option but that would bypass your SX's nice RIAA EQ phono preamp.
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To my understanding its a ceramic cartridge...and i know its the original because it cant be changed. my table isnt exactly "newer" either. its a 1968 GE Glaser Steers table
 
back to this since my hand is getting better after i broke it, im starting to build up the parts list for the next mouser order to finish recapping the rest of the unit. current plan is re build the tone amp and phono board and i might do the tuner. so far all ive gotten in C29 and C30 tantalum are being swapped out with film caps. 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?

Currently looking at Panasonic ECQ for the tantalums. any better options? i know the 0.012uF rating can be changed around but by how much? some digging around looks like 0.1uF is a good value.
 
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
 
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