JJ-100 Troubleshooting

[Purpletele]

Looking for a little advice or some ideas for troubleshooting on my JJ-100

I had my amp at a studio and had just left when I got a call from a colleague that said the amp went down when he switched from clean to dirty.

He said there was a click and then everything went quiet.

I assumed a pre-amp tube and rolled the tubes one by one and then I tried 4 new tubes at once. (Found one new tube to be bad)

I haven't pulled the chassis yet, but so far I have power to all of the tubes and the pre-amp tubes are not an issue that I can tell.

My next suspect would be the switch for clean to dirty.

Anyone have a similar issue or have an idea of what may be the issue?

Thanks for any ideas or advice

Brian V

 

[LP Freak]

Looking for a little advice or some ideas for troubleshooting on my JJ-100

I had my amp at a studio and had just left when I got a call from a colleague that said the amp went down when he switched from clean to dirty.

He said there was a click and then everything went quiet.

I assumed a pre-amp tube and rolled the tubes one by one and then I tried 4 new tubes at once. (Found one new tube to be bad)

I haven't pulled the chassis yet, but so far I have power to all of the tubes and the pre-amp tubes are not an issue that I can tell.

My next suspect would be the switch for clean to dirty.

Anyone have a similar issue or have an idea of what may be the issue?

Thanks for any ideas or advice

Brian V

Your best bet is to email Dave. He’ll get right back to you with the correct info and not a lot of guesses like you’ll get here.

 

[Purpletele]

I sent a note and received a return note from Dave.

HT fuse and a new set of power tubes with a little bias work.

 

[LP Freak]

I sent a note and received a return note from Dave.

HT fuse and a new set of power tubes with a little bias work.

 

[mniel8195]

I bet it was a fuse.

 

[Purpletele]

I bet it was a fuse.

It was a power tube going bad and set off the HT fuse.

New tubes and a bias adjustment and I am jamming

 

[LP Freak]

I bet it was a fuse.

It was a power tube going bad and set off the HT fuse.

New tubes and a bias adjustment and I am jamming

Yes, fuses blow for a reason

 

[CrazyNutz]

I bet it was a fuse.

It was a power tube going bad and set off the HT fuse.

New tubes and a bias adjustment and I am jamming

Yes, fuses blow for a reason

Actually they can blow after years of the amp being switch on-off with no actual problems. High inrush current when the amp is turned on from the filter caps charging stresses the filament overtime.

If you blow a fuse more than once in a short period of time, there is a problem.

 

[Purpletele]

I bet it was a fuse.

It was the HT fuse that tripped because the power tubes were failing.

 

[LP Freak]

I bet it was a fuse.

It was a power tube going bad and set off the HT fuse.

New tubes and a bias adjustment and I am jamming

Yes, fuses blow for a reason

Actually they can blow after years of the amp being switch on-off with no actual problems. High inrush current when the amp is turned on from the filter caps charging stresses the filament overtime.

If you blow a fuse more than once in a short period of time, there is a problem.

Ok, typically fuses blow for a reason.