Pioneer SX-780 problems

So I've got everything installed but FU3 blew immediately. The circuit protection relay is not kicking on :(

Help!
 

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Ok, when I get home i'll remove each power pack and attempt to power it on, see if I can limit the problem to a single channel.

FWIW, I have already retouched the solder on the 3 power transistors, they actually look pretty good.. there is no evidence of excessive heat on them

I've looked over the board pretty, I see no visible shorts from bad solder or wires touching. Any suggestions on where else to look?
 
So, both packs are removed, fuse still blows. I'm fairly confident its unrelated to the replaced resistors and transistors I've replaced. I did not have a 1A fuse to put in that place when I took voltages before.

So, with both packs removed the circuit protection kicks on again

I might be going down the wrong rabbit hole, but I took voltage readings on the 3 power transistors, here are my readings from back to front:
Q25: 2sb712
B: 14.03
E: 13.41
C: 25.80
Q19 2sd325r
B: 40.5
C: 39.9
E: 49.8
Q20 2sb536a
B: -40.6
C: -40.0
E: -54.1​
 
Thanks pete for your quick response!

I tested these in-circuit, let me know if I should lift a leg

In order from left to right
D7: .001
D6: .566
D9: .563
D8: .561

On another note I meant to put in my last post... the 1A fuse in FU2 has blown twice, seems random, but FU3 blows everytime
 
logically d7 doesn't make sense .. but logic isnt my friend .. yes it looks bad . check them all out of circuit .
bit of odd logic try pulling fuse 2 and checking d7 again .
 
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FU2 was removed already in my last readings, because it blew

Well I completely removed D7 and I'm still getting .001 - .194... more often its closer to .001

The rest with the emitter side removed:
D6 = .555
D9 = .558
D8 = .556
 
Ok, will any 200v 1A diode work, or should i use the AK recommended 1N4004? D6-D9 all had a soot like coloration on them, it could be paint or protective film... The diodes directly above them (d10-d13, SR3AM-8) have a similar coloration
 
Progress!????!?

Diodes installed & 2 new 1A fuses installed, DBT did the normal flash at power on... Relay kicks on, no blown fuses, DBT is off

The power packs are removed, should I put them back and see what happens?
 
Good news, sorta

As you can see, I have the right channel working, its one of the original darlingtons and it sounds terrible.

Apparently both new packs are no good, either DOA or I fried them at some point

Anyway, this one "working" darlington has bad sound on the speaker and headphones with any input. Sounds like the gain on the Bass is too high (I haven't adjusted the dc offset or anything)

With the other original darlington installed the DBT is glowing and the protection relay doesn't kick in.

I'm going to see if I can return the packs I bought off ebay, cant decide if I should try to get a refund or replacement.

I've read that some people have had to order 6 to get 2 working packs, so I might try the rcs16 mod recommended by awesomeaudio earlier

Thoughts?
Edit: The ebay seller refunded my money already and has requested they NOT be returned, so that was painless

20170428_193437_resized.jpg
 
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I'm going to try another set on Ebay from a seller that has apparently sold 208 sets. I've been reading over the rcs16 mod and i'm not sure if thats something i could tackle

So, i moved the one working darlington to the other side and it works there and sounds much better. Would that be a DC offset calibration or bad caps?
 
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