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Base theme by DesignModo & ported to Powered by Vanilla by Chris Ireland, modified by the "theFB" team.
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"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Worth saying the old power amp valves was replaced because it suddenly lost power and had a purple lightning show in one valve.
Try tapping on each of the power valves with the amp on and see if you get a rattle or crackle - you'll have to take the back panel off to get at them easily, so be careful. If it is a valve problem it's common for it to be so vibration-sensitive that you will often get a noise even when tapping the other valve, so hold the one you're not tapping with a cloth.
It's also possible that the dying valve damaged something on the PCB above it, which is quite common on Blues Juniors unfortunately...
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Is it worth trying another set of valves?
I am getting a slight burning smell with both sets of valves too.
This is fairly normal with BJs, they run too hot. You can help it a little by reconnecting the power transformer for the correct 240V UK supply rather than the 230V Euro-fudge as Fender (legally have to) supply it.
To do this, locate the white/black striped wire which comes from the bundle of wires on the transformer and goes to the power switch, and the black wire which goes to P6 on the PCB. Swap these. (You may need pliers to pull the connector off the PCB, they're usually very tight.)
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Definitely gets worse with the fat switch on, without the fat switch it's not that loud and I could live with it, but then the sound is flat.
I do have loads of buzz with different guitars (both shielded and wiring checked recently), earth connectors in the amp look okay though.
Throw it off a high building and then go and buy a Hotrod Deluxe.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
Try pushing the ribbon cable to the power valves away from blue wire from the output transformer.
So... for £40 I've brought a tested pcb, with all metal jacks, valves, bias mod, that all works. Sod it.
The Rat Mods chap sells them off sometimes after he's rebuilt one.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
I'm not really happy with mine but can't be arsed to sell it either because it doesn't seem to be worth more than a good pedal.
The Session Blues Baby is designed to be a drop-in fit, for one...
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
If you install a used board change the 47 pF cap across the phase inverter for a 220 pF 1 kV cap (from memory this is C9).
This will make the amp stable and prevent oscillation in the future.