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Blues Jr mod info


HamerDave

Question

Posted

Does anyone know if the Fromel stand by switch mod is the same as the BillM setup for the Blues Jr? It seems Bill isn't doing well healthwise and they're not taking orders for kits right now. 

6 answers to this question

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Posted

So I took a leap and got the Fromel mods. The standby switch is the simplest installation you could ever ask for. No soldering. No fiddling with the high voltage side of the transformer. Completely plug and play. I'll be installing the "Supreme" mod kit today.  That'll give me a chance to use my spiffy new soldering iron..  😎

Posted

Installing the kit was super easy. The instructions were easy to follow and the board is well labeled. Be very very careful not run your iron too hot as you run the risk of lifting the traces off the board. I had that happen on one cap. If you run into that scrape the masking (the green stuff) carefully with a sharp pen knife along the trace until you've exposed the copper. You need to be super patient and careful here guys. That copper is only a few mils thick..  It's electro plating. [start random old guy rant] damn but I miss the days of point to point wiring in guitar amps. They were so much easier to work on. /rant  Then flow solder from the exposed trace to the hole where the pad lifted...

Anyway, the whole process took about 2 hours. I'd like to give you an idea of the changes in sound but I'm still running down the problem that started me going down this road. The power tubes failed and popped the main fuse. I bought and installed a new set of Mullards (pre and power) and replaced the fuse. The amp runs but I get a nasty sounding breakup when I push the signal even slightly.  It sounds like an intermittent short. I've been scouring the web and talking to some amp gurus locally and they're pointing me to the connection between the ribbon cables that connect the tube sockets to the board. I'll let you all know what we get once I get that sorted out..

 

Posted

So I haven't been able to track down the root of the problem. Jr will have to see a real amp Doctor. It's going to be a while as I'm a bit tapped these days.. 

Posted

If you haven't already, you might check, re-tension, and possibly re-flow the tube sockets - especially for the power tubes:  http://billmaudio.com/wp/?page_id=171

I picked up a chicken-fried Blues Junior cheap from CL on Friday... and so I'm right behind you.  After tearing it apart Saturday, it looks like there was a screen grid failure in one of the EL84s that blew out associated resistor and a couple board traces.  Ordered a new JJ set for it, and once I get the damage cleaned up, I'll probably do the power and tonestack cap mods as well, and add a bias trimmer (assuming I can get it functional in stock form :D ).

Posted

Last I looked, Bill's son says his Dad's site may be back up this month.

I have done most of  Bill's mods to my Blues Jr. After having the chassis out so many times, the ribbon cables started to fail so I swapped them with straight wire. Then I starteed to get the common (as per Bill) issue with the power tube sockets , re flowed them a few times, did not prove to be a permanent fix. Being stubborn, I pulled the entire tube board and replaced it with a kit available from Hoffman amps which has all the parts (except the wire I believe) spring tensioners etc. You wind up with a point to point tube board. Not for the feint of heart (scant instructions..I basically used the original board as a template to retrace the paths).  No more power tube issues now.

The amp is now working great but, the presence / clean boost mod is no longer working. Probably a bad connection somewhere but if Bill's site comes back up I'll buy an entire new kit. Or, I wonder if the other mod shop mentioned above has something like it. I'll check. No more amps with pwa boards after this never ever never ever ha ha. I have tinkered so much with this one I have an odd relationship with it.. like my little frankenstein amp.

This amp was also abused at a jam, someone unplugged the speaker cable, plugged it back into the foot pedal socket. By the time I realized it, the power tubes were fried.

And best of luck to Bill, he has been a great guy every time I have dealt with him

 

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