Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jonyoungyi on July 08, 2017, 03:56:38 pm
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Hey all, just finished wiring up a Tweed BluezMeister, but every time I turn it on the Power Resistor between my B+ and C burns up. When on standby, the tubes glow fine, but as soon as I connect my A voltage it burns up. Per a respected forum moderator's suggestion I used a 20k/3W resistor, as I am using a Solid State Rectifier.
To my understanding, something "down the line" is drawing more current than it needs to, which from what I read, could mean something isn't grounded properly.
I've attached a layout that I made based on the original Hoffman BluezMeister layout (attached). Really the only change I made was adding the two 470R Power Tube Resistors on board, adding two extra lugs.
Double checked all my connections (used Hoffman's recommended trouble shooting method) and all my connections/jumpers seem correct.
Was curious if anyone can shed some light on where else I can check, as I know it can be a lot of things at this point.
Thanks, everyone!
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Look for a short from node C to chassis. Use your ohm meter and measure the actual resistance from C to chassis.
Filter cap could be bad or installed backwards.
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Thank you Sluckey!
I was reading 10k on nodes E and D (not sure if that's normal), but 1.5k on node C. I checked that node with continuity to the chassis and sure enough I was getting continuity! It was intermittent, so that would explain why I didn't catch it the first time I checked!
When I lift the 22uf 500v FT cap at a 45 degree angle I would get continuity. When I flatten the cap out horizontally, I wouldn't get continuity.
Looks like a new cap and I should be on my way, unless you think otherwise!
Thanks so much for your quick reply and help! I really appreciate you and so many others on here!
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Just to be sure... Disconnect the node C cap and power up. Does the resistor still burn?
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Sluckey! I spoke too soon! The continuity was still there even without the filter cap! Turns out I had burned two jumpers together without even realizing. Both had thick, black insulation, so they blended together well... As soon as I removed one of the jumpers and resoldered a new jumper, far from the other, the continuity ceased!
I soldered that filter cap back on and it fired up first go! MAN... this thing sounds great!!! My notes have so much attack, I love it!
Here's some pics! Annihilate my lead dress please! :D
Oh, but seems like my Trim Boost doesn't do anything when engaged and rotating the pot, but seems like a minor fix!
Thanks, again, Sluckey! You are an amp savior!