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Post subject: Blues Jr - No tone control
Posted: Thu Nov 03, 2011 3:32 pm
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Hobbyist
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Joined: Wed Feb 09, 2011 12:33 pm
Posts: 1
I have an old Blues Junior, Made in USA, green board with tone controls that seem to be bypassed. The Bass, Middle and Treble controls do not seem to have any affect on tone when turned from 1 to 12.
It appears that the Treble pot was replaced and the chickenhead knob was glued in place with silicone. There is whitish residue all over the backside of the treble pot. Usually a bad treble pot will silence the amp. However, all the pots appear to be functional when tested with an ohm meter. There is no visible damage on the back of the pots from the knobs being forced down and cracking the epoxy on the pots.
The amp works, volume and master volume and the tone isn't too bad. It behaves like a Champ (no tone control...only volume).

Any help on next steps would be appreciated.
Thanks


Last edited by pjdiaz on Fri Sep 14, 2012 5:11 pm, edited 1 time in total.

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Post subject: Re: Blues Jr - No tone control
Posted: Thu Nov 03, 2011 6:24 pm
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Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Measure the value of each pot and trace out the circuit.

http://support.fender.com/schematics/gu ... ematic.pdf

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Post subject: Re: Blues Jr - No tone control
Posted: Thu Nov 03, 2011 6:48 pm
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Joined: Fri May 15, 2009 12:39 pm
Posts: 1466
Location: Birmingham UK
Thats odd.

If the pots themselves test out OK but genuinely don't have any effect on the sound, then yes, they've been by-passed on the board. Did you acquire the BJ 2nd hand?

That said however, I was so unhappy with my stock BJ when I bought it from new, that I nearly returned it. It was harsh and none of the EQ controls seemed to work properly, even after the speaker was broken in. On a whim, I changed the stock "Emminence made for Fender" speaker to a brand new Celestion V30, because my other amp had one (yes I know, very scientific..). And there it was - a great sound and with EQ controls that actually did what they were supposed to do. Just a thought..

Lord alone knows why Fender chose to hobble a potentially fine amp with such a crappy driver - keeping the cost down I suppose. I sincerely hope the mk3 BJs have had this affliction sorted..

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