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Pioneer SX-636 30V on left output

i forgot about that trimmer pot issue...but i get a new half pound roll of 60/40 solder and started on the power supply.
IMAG0108[1].jpg
thats what it looks like before i started on it. i started on it last night and holy **** the new solder smokes like a steam train. i think i accidentally inhaled the fumes because my throat has been burning since i started on the power supply last night and all of today. will post after i finish it.
 
Looks great! Eye-balling the diodes and the caps from your before photo to the after one to check for proper polarity was easy because you posted identical images that could be scrolled back-and-forth to. Nice!
 
Bassblaster said:
ITS WORKING!! GTQUIWFGKUJHOVFDGJIKVDGKJFWEDASGKJPUI
all i got left is to re cap the power supply and replace the lamps and i think i can call this project done...for now. i plan to come back later and recap the rest of the unit.
Click to expand...
congrats on the progress!
 
it should be marked on the board ..
if resistance is changing through full range whilst its on the board it must be fitted correctly ..
in this case it is like B
resistors.gif
 
well then .. i just happened to check the schematic and no wonder the offset wont adjust ..the pots are for bias .. no adjustment pots for offsets .
 
Just went back and looked at your pics, I guess we share the same version of the amp board. In a moment of desperation I checked out some boards available on ebay and noticed there are later revisions.

I ended up taking mine to the local audio guy to get some tips. Nothing is solved yet, but I was able to confirm 100% my power supply is good and the output transformers aren't at fault. My next step is replacing the wirewound resistors, since the other resistors I swapped out (R24, R26) didn't change anything. I noticed yours aren't the same brand as mine, not that it makes a difference. Or does it. Im getting wild +/- swings in DC voltage, from -32 vDC to -17 some part is not operating under load and I haven't figured it out yet.

It doesn't help that I need to recap parts of the AF amp, it's not stable either

On the bright side, I did score a Fluke 87 for $20 at an estate sale.
 
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I can't remember did you replace the drivers? Also how do you know the amp board is the problem? It's possible the amp is just doing its job and amplifying some DC from the pre amp. Are you sure that's emitter resistors are bad? They should test out at 0.5 ohms. If they test bad replace them with a 0.5 ohm 5% 5W wireround
 
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I didn't replace drivers, just capacitors and transistors on the entire board of 034. There was +.01-.03 (or was it .001-.003) volts DC coming into the R channel from the pre amp and I am pretty sure I found the faulty capacitor but that wasn't enough to account for the voltage at the R output terminal.

The past few days I've started where the pre amp fed into post 5 (since I've got right channel issues) and followed the schematic. I measured all the elements and/or compared to the L side until I encountered DC voltage after C4 & C6 that looks like it was coming from the power supply. Since power is being fed thru the L channel and over to the R, I'm assuming the problem is in the R circuit. I've tested virtually every resistor, transistor and all but a few of the small caps.

The voltage is fluctuating, in my uneducated opinion that might indicate a part not functioning under voltage but under lower "strain" does the job. After 3 months on this, I'm just going to replace everything until it's completely rebuilt.
 

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Ive been really sick that past few days and finally got around to plugging the 636 into the wall after the power supply recap. powered it on and....no booms, pops or what not. now to adjust the BIAS
 
BIAS adjusted good. man i had them all kinds of messed up. left was at 80mV and right was at 5mV. i got the left to 19.8mV and the right to 20.1mV
 
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so it seems like the DC offset is connected to the bias. ill have to remember that if i get another piece of gear that the offset wont adjust
 
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