Pioneer SX-1000TW Repair

[w9nl]

First post so go easy on me 🙂

I bought this non working reciever as a learning project and hopefully bring back to life. For starters it had a blown 3a fuse and some burnt resistors on the Main Amp Unit board. I found a manual and with my limited skills and test equipment I've replaced the resistors and found I have 2 output transistors that are bad based on using a DCA55. I've pulled the 2 output transistors and can power up the reciever and the right channel seems to be working ok. Ordered 4 new output transistors and some caps for the power supply, head amp and main amp board. Replaced the caps on the power supply board and the left channel side on the main amp board. Decided to pull the right channel output transistors and do some voltage checks on the main amp board to see what might be wrong on the left channel ahead of getting the 4 new output transistors. I'm seeing some voltages on the left channel that are almost double what they should be. I've tested all the transistors on the left channel portion of the main amp board and they all test ok using the DCA55.

I've read some comments that you can't always trust the DCA55. Can anyone comment on that or some possible other areas to focus on?

Thanks much

 

[busaboy]

Unfortunately unless you replace every bad part, some of these new parts could blow again when power is reapplied. You should not be testing using power until you are reasonably sure you fixed the unit. Asking people to help you remotely diagnose problems in a power amplifier or any other product that can easily self destruct when a single component is bad is an exercise in frustration....