JJ-100 Troubleshooting

Purpletele

Purpletele

New member
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
 
Purpletele":305xh6n0 said:
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
Click to expand...
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.
 
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.
 
I had a "Hum" sound coming from my BE-100 one day and Dave said it was most likely a Defective Power Tube though still pretty new set 4-months old. The second time I turned the amp on the Fuse Blew? Sent the amp to Dave and he told me it was "Also the Capacitor" which was causing the Hum (reason for the blown Fuse) I sent a New set of TAD EL34's and Dave said three of the four were Bad?

Dave did the repair and installed a New set of "EH" EL34, now after a year and many hours of play time, the Amp sounds great and consistent. Tube reliability has been bad especially EL34, Dave does wonderful work (along all the modifications to my amp).
 
LP Freak":1l7ge5at said:
Purpletele":1l7ge5at said:
mniel8195":1l7ge5at said:
I bet it was a fuse.
Click to expand...

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

New tubes and a bias adjustment and I am jamming
Click to expand...
Yes, fuses blow for a reason
Click to expand...

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.
 
Working with electronics and dozens of amps for decades I've only had one time that a Fuse Blew from old age or stress, one of my SLO's (8yr old Heavy Road use) but never a relatively new amp. It does happen though....
 
CrazyNutz":37xlfkw6 said:
LP Freak":37xlfkw6 said:
Purpletele":37xlfkw6 said:
mniel8195":37xlfkw6 said:
I bet it was a fuse.
Click to expand...

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

New tubes and a bias adjustment and I am jamming
Click to expand...
Yes, fuses blow for a reason
Click to expand...

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.
Click to expand...
Ok, typically fuses blow for a reason.
 
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