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SX1050 No Power

I

INSPrGadget

New Member
Hi all, please forgive me if this is a topic widely discussed somewhere I can't find, but I've been doing a recap and restore of an SX1050 and all was good until I replaced the power transistors with the wrong thermal paste (it was conducive and messy). The fuse blew and I accidentally replaced it with a 12A fuse instead of the 10A that was supposed to be there, powered it up and the paper around the soft start resistor caught fire! I have since built a dim bulb tester (I know I know... should've been the first thing I did. I'm learning; albeit the hard way), installed the correct fuse, and tested all the components on the soft start board. They seem fine. I replaced the power resistors (this time with the right thermal paste, and put everything back together. I have tested the dim bulb tester. It works great. Now I get nothing. No lights no clicks... nothing. Any help would be greatly appreciated. This is my first monster receiver, but not my first electronics project.
 
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Sounds like you blew your power output transistors, and most likely in the process damaged more components upstream in the process. Your fuse most likely blew instantly hence your no power.
 
Your thermal fuse in softstart circuit most likely blew. Check the following thread/post

Pioneer SX-1050 main fuse 10A blown

I got this Pioneer 1050 which had outputs blown before. I rebuilt the power supply boards, replaced output transistors (8 of them) and replaced some parts on power amp board due to previous issues. Then it was working fine. Then put it away for a week. Today, I turn it on and 10A main fuse was...
audiokarma.org
You mentioned the soft start resistor caught fire.. Did you test it by lifting one leg. The thermal fuse is attached to the underside of the resistor.
After you fix the soft start resistor and thermal fuse, power up in DBT (with the output transistors disconnected)
 
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It is unlikely that the output transistors are damaged. You essentially connected the collectors to ground on the heatsink, which would cause a direct short to ground on the + and - power supplies. there would be no current flow through the output transistor junctions, so they should not be damaged.
 
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