JCM 2000 DSL 50 Power switch flickers on power up

[jball85]

Hey everyone. I believe this may be the first time I've actually posted here, so greetings from Texas.

The issue -

On my DSL 50 when I flip the power switch (red illuminated toggle) the amp is delayed up to 5 seconds before the switch lights up and the tubes receive voltage to their heaters. As soon as the voltage does arrive it flickers off then back on once, as if it's intermittent. However, after the heaters/power switch has gone through this "routine" and I power it off and then back on, it behaves normally as it should with no delay or flickering. After the initial power up issue the amp works as it should. The tubes are fine. The only other components, aside from the tubes, I can see in the schematic in heater supply circuit path are the BR62 rectifier and (4x) 3300uf 16v Electrolytic capacitors. The BR62 and capacitor network appear to provide DC voltage to the heaters of the first 2 preamp tubes.

The way this amp was designed makes it extremely difficult to troubleshoot this area of the main PCB, as access to the previously mentioned components is blocked by the FX loop/speaker jack PCB. Although I can remove the main PCB, in order to do so means disconnecting numerous OT, PT, and ground connections, as well as numerous molex connectors from the preamp and rear pcbs. Then rigging it up for testing, UGGGGhhhh. I'd also have to desolder a choke. I'm considering just replacing the caps and BR62 to see if it sticks and solves the problem. I'm limited on free time in my life, so pulling the main PCB and putting together a test rig just isn't a reasonable option to me.

Below is a pic of the inside of a DSL 50 chassis (not mine in particular). You can see the right half of the bottom tube (main) PCB is covered by the rear PCB containing the FX loop speaker jacks and other things.

chassis pic.jpg

I suppose it could be a mechanical switch issue, but I have doubts since this only occurs on a cold start.

I can't seem to find anything on the web resembling this problem that someone has encountered before, or I'm just not wording it correctly.

So if anyone has encountered this before or has some insight I'd appreciate it, and I'd like to hear it before pulling the chassis and breaking the amp down to replace components.

I've attached a schematic, the BR62 and caps have bold underlined red text below them.

DL50-60-02 (2003) iss7.pdf

[xtian]

Hello from Chico, CA! The switch has a 120vAC neon bulb, wired to the mains. Its strange behavior is no surprise--it's failing. Replace it.

[jball85]

Thanks for the quick reply, I'll slap a new one in.