Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TerryD on June 26, 2014, 10:50:17 am
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I got the F&T caps for the power section. Seems like they have pretty good reviews? On the vibrolux, my first two caps are newer Illinois and I will be swapping those also. Just to be sure, are they in parallel or series?
Also concerning the power caps AND the board.
Whoever put this amp together must have been on the rag that particular day. These resisters and caps are "IN" that board. I don't know if he/she twisted them in there with a ton of solder or what. But when I tried getting a couple of resister out I basically cut them off and soldered to the left over wire. Now I want to do all my caps and maybe a few resisters. What is the professional (semi-professional) way to go about this in this situation?
Should I clean up all my solder joints now as well??
Thanks!
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I don't know if I understand what you are doing. Are you making a wholesale component changeout?
Can you snap a picture of your board? Is it a circuit board or a turret/eyelet board? If you are having trouble getting the components off, just to change them, why not pick up an empty board and put all your new components on that one. That is, if you are making a complete swap of components.
Jack
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You probably need a solder-sucker if you have big hairy globs of solder in there. Lacking one of those, you can heat up the solder joints, then heat up the eyelet joints and quickly smack the board against something stiff that you don't care if it gets some solder splash to get the solder blobs out of the eyelets.
WEAR EYE PROTECTION!
WEAR EYE PROTECTION!
WEAR EYE PROTECTION!
Ideal is to remove, then clear off the entire under-doghouse board. With some alcohol (prefer 91%, much better than 70%) and a stiff brush, get the old flux off the board. Start new.
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What Eleventeen said.
Ideally, you'd make a diagram of how everything is positioned on the board before parts-swap, to include the color-coding of the wires at each specific eyelet.
Then be sure caps are discharged, unsolder the wires, and un-bolt the board from the chassis. When the parts were originally installed, the leads were inserted through the eyelets, then bent towards each other, then trimmed to length. The parts' leads should hold them firmly in place without any solder. The board was bolted in place over the insulating board, wires installed in the proper eyelets, and then all eyelets soldered.
The first 2 filter caps were installed in parallel according to the Vibrolux schematic (http://el34world.com/charts/Schematics/files/fender/Fender_VIBROLUX_AB763.pdf). As long as you're using caps rated 450v+, yours should be in parallel too (2x 16uF in parallel).
If the newer Illinois caps were rated less than 450v, someone might have taken 47uF caps (or a similar, higher value) and placed them in series. Some wiring would have changed as a result, and they should have used 220kΩ resistors across each cap if that were the case. This wouldn't be "wrong", just different.
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Thanks again. Terry