Just acquired a fried Blues Jr

[Telluride]

Hi All New Member here. I used to mess around doing light modding on Fender amps years ago but it's been quite a while. I recently got an attacking of feeling like my life was not complete unless I had access to Fender cleans. I have a couple of friends who have BillM modified Blues Jrs and I've been fairly impressed with them. One in particular that has the 6v6 conversion.

I ran into a cream board BJ that was fried but I decided since I was going to take on the mod project anyway that I would also take on getting the thing up and running.

So here's what going on with it. The tube board is burnt and the traces trashed on V5 where the ribbon connects to the traces for pins 7,8 and 9. The 47uf power supply cap is leaking but the 22uf caps look ok. I was thinking of replacing the wiring and connecting directly to the socket pins on V5 just to see I I can get it back in working order before starting the mods.

Is it possible that all the circuit board damage could be caused by a failure in the tube or is it likely to be a power supply problem or both?
From what I've read regarding other people trouble shooting it seems like it's ok to power it up without the tubes installed to check basic voltages. Is that true?

Any and all suggestions are greatly appreciated.

Thanks
Randy

[ampgeek]

Welcome Randy!

Yep...a failed tube can often lead to power supply system issues.

And..yes...it is OK to power up an amp with all of the tubes removed.

I suggest that you take a couple of clean/clear pictures of the amp as it is now and post them up here for review. Make sure to get some close ups of the burnt areas for good measure.

I am not much of a BJ aficionado but there are some here that are and will likely provide some good advice.

Cheers,
Dave O.

[ampgeek]

I forgot to mention that you should seriously consider whipping up a light bulb limiter for your initial trouble shooting efforts.

There is a sticky in the Technical section that will get you there pretty quickly.

Good luck,
Dave O.

[M Fowler]

If you don't want to repair that amp you can put in a new circuit.

https://tubeamparchive.com/viewtopic.ph ... ues+junior



Also Doug Hoffman Amps has boards, schematics and layouts to gut and convert the BJ amp.

http://el34world.com/Forum/index.php?topic=17845.0

[Stevem]

If you rebuild to near stock, plan on replacing all of the big gray cased power supply filters even if they seem to work as they where near crap when they where new and there failure rate after even just 6 years is quite high!

[Telluride]

Thanks to all who responded. Got the amp working.
i jumpered over the burnt traces and decided to turn it on and see what happens. Big arc and some flame from the same spot. I then looked at all the solder joints where the socket is soldered to the board. With a magnifying glass I though I could see some fine lines in the solder around the pins. I resoldered all the connections in that area of the board and that did the trick.

I'm going to get the thick replacement board from Hoffman
Amps and redo the whole board hardwired.

I'm now waiting for a friend to mail me some documentation on some of the BillM mods. Since he is not currently selling kits due to his illness I'll have to source the parts elsewhere. Hoffman Amps looks like a good alternative. Thanks for that link and thanks for mentioning the lightbulb device.

[ampgeek]

Nice job mate!

You are well on your way to succumbing to the joyous addiction that is everything tube amp!

Welcome to the fold,
Dave O.