Pioneer SX-636 blowing fuses

[Sibley]

Hi there, I picked up a SX-636 today that ended up having an issue right off the bat. I'm wondering if some of you with some experience could have a look at the schematic that I'm including and tell me if the problem could be the 4 diodes that are all connected. fuse 1 and 5 both blow as soon as its fired up. They don't lead anywhere except the transformer and to these diodes. when I replaced the fuses I had volume and sound from both channels for a split second. Then that fast i did not as i watched the fuses blow. Thanks in advance for any help.

 

[soccerfan]

Most likely a blown output, which is drawing too much current and blowing fuses. Remove and test all the output transistors first . Then test everything in the driver amp
First step would be to build a DBT (Dim bulb tester) and use that so that you can prevent the fuses blowing up when you work to get it back working properly.

Dim Bulb Tester Build and How-To

I put this together based on the pics that @Jailtime posted a while back, and figured I'd take some in process shots. There were a number of threads on these with dead links to imageshack or photobucket (the scourges of the internet) so this should be a good post on the issue that won't have...

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[Sibley]

I actually just purchased a dim bulb tester and I haven't even used it yet. So that will be great to try out.

 

[markthefixer]

BUNCH OF SHOOT ON SIGHT TRANSIST0RS IN THERE, 2SC1451...ALSO SANYO CAPSISTORS. CLASSIC

2SC1451 CAUSES THE OUTPUT TRANSISTORS TO SHORT (DIE) WHEN THEY POP

PLENTY OF FOUND KNOWLEDE ON THIS IN THE OLD THREADS.

 

[fromnowon]

Have fun with your SX-636 @Sibley !

I still have mine and did a full restore on it back in 2019, with help from here, and it came out great. (It was blowing fuses as well).

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Hello, Today I ran into a "for parts" SX-636 for $20 because it had a channel out (right channel) and I figured what the heck, maybe I can learn something by trying to diagnose and fix it, so I bought it. First I cleaned the controls and still no right channel, then noticed this: right channel...

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New sx-636 Refurb Issues and Questions

Hello, Pioneer Forum. I think I'll start a fresh SX-636 thread, if that's ok. (I had a really great success recapping an SX-434 this summer, thanks to help from you guys on this forum. I still can't believe how great it turned out. I gave it to my son after enjoying it for a few months. It...

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