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SX-750 Stuck in protection, smoking resistor.

alexprollock · 2022-06-12T06:47:46+00:00

Howdy everyone. As mentioned, I've managed to get my 750 stuck in protection mode. Full disclosure, I am a rookie that now has huge respect for what you guys do. I recapped the AWR-099 board to get rid of the hum in both channels...it worked, no issues there. But I had the transistors as well, so I figured I may as well replace those too. I replaced all transistors on the board, testing it after each one. I had no issues until the final two that I replaced (Q8 and Q10), my big rookie mistake here is that I desoldered Q8 with the unit still powered on...this is before I knew about DBTs. I replaced the last two, hoping I didn't fry anything, but sure enough, the relay won't click. Now R29 (the big 150 ohm insulated resistor) is smoking when I power on the unit. I've since built a dim bulb tester, and checked the resistance of all resistors, as well as the diodes. The light on the DBT is 100W and lights up bright, then dims to nothing when the unit is powered on. I've gone as far as I'm comfortable with and am hoping to find where the problem lies. I suspected that I may have fried the Zener at D10 and ordered one, but I wanted to reach out to you folks first before I start shotgunning parts and making things worse. Thanks!

Thread starter alexprollock
Start date Jun 12, 2022
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pioneer protection mode sx-750

alexprollock

New Member

Jun 18, 2022

markthefixer said:
insulate those probes!!!! they slip, we ALL slip!!!

insulating them protects against shorts that can be devastating.

They are insulated, I’ve been digging through the forums and taking bits of advice as I found it.
I appreciate the heads up!

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