Fender blues junior bias adjustment

[philcarson]

Newcomer to the forum and looking for some help

Id like to install an adjustable bias pot to my 2015 FBJ. Ive seen pots in the catalogue and not sure what value is needed and where the pins are connected to the board.
While the board is out any tips on rectifying other issues?
Many thanks

Phil

[sluckey]

Hoffman has the parts. Here's a proven bias mod...

[Paul1453]

I was just wondering if maybe C33 shouldn't be changed to 50V as the TP is showing -26.5 which is over the 25V shown for C33? 

[sluckey]

yes

[Fresh_Start]

Adjustable bias is the first thing I fixed in my Blues Jr.  Power tubes were biased so hot before, they only lasted a few months.

Not trying to be a buzzkill, but opening up a Blues Jr. can be hazardous to your mental health. Yes, lots of guys have done tons mods to this amp. However, those ribbon cables are problems waiting to happen. Every time you move the board you risk breaking one of those fragile solder joints. There is a very good reason Doug Hoffman sells replacement circuit board for these amps.

Respectfully,
Chip

[philcarson]

Hi
any details about how you installed your adjustable bias mod and what values you used?

[Fresh_Start]

reply #2 shows a pic of how I added adjustable bias.


http://el34world.com/Forum/index.php?topic=10029.msg91414#msg91414

Chip