Good evening!


Replaced the following components:

• Q507
• C426
• R505
• R506
• Q429 (found bad and replaced as well)

I powered the amp on using the incandescent lamp in series. Initially, the lamp glowed brightly and then dimmed, which is normal. After cycling power a couple of times to check if the relay would engage, the lamp went out completely and the main power switch popped open.

There was no smoke and no hot components.

When I checked the bulb, I found that its filament had broken. It seems strange to me that the amplifier could blow the bulb, since even a severe short circuit in the amp should just make the lamp burn at full intensity rather than burn out.

All internal fuses on the amp are still OK. Unfortunately, that was my last incandescent bulb, and they are very hard to find locally now as only LEDs are available.

Is there any static check I can perform next before sourcing another bulb?
Thanks!

 

Edit: Upon double-checking, the test bulb is actually OK!

I realized that the main power switch popped because of an internal fault in the illuminated indicator bulb inside the power strip (multi-plug) switch I was using to toggle power. That indicator light was working before, but it is now completely off.

What do you think?


thanks!

 

For the time being, get another power bar to power the amplifier.
You can trouble shoot the bad power switch later.