Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: silat on May 20, 2020, 11:49:50 am
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Does anyone see a problem? I have never used this type of switch. Amp does not lite up. Did I wire it wrong?
I will post pics later. the files sizes were to big.
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Here are pics.
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More pics.
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why just suspect the switch?
disconnect the secondary of the PT, tape of and test your fuse again
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I removed both red wires and smoked a 10 amp fuse in the variac.
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It looks as though the fuse is wired in parallel with the primary instead of in series with it. This would put a direct short through the fuse for the line voltage. But it seems this would blow the fuse. Maybe pictures of the back of the switch would clarify.
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If twisted pair, black wire and white wire, are your hot and neutral coming from the wall, then yes, the switch is wired wrong.
If above statement is true about the twisted pair, and the untwisted white and black are the ones going to PT primary. Here's what's happening;
When you flip switch on, the wall Hot (white wire in twisted pair) conducts to the fuse, out of the fuse, and DIRECTLY to the wall neutral (black wire in twisted pair).
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What's up with the black oily looking substance on the wires leading from the power transformer?
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If the twisted pair is indeed wall voltage, and untwisted black and white are PT primary, do this.
Disconnect and throw away short black wire that is going from fuse to switch in pic.
Disconnect untwisted white wire from switch, attach that to newly opened fuse location.
Now you have ;
black and white twisted pair to lower 2 switch tabs.
Short white jumper from switch to fuse tab 1.
White PT primary wire to fuse tab 2.
Black PT primary wire to top switch tab.
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Believe that code says Black hot, White neutral.
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What's up with the black oily looking substance on the wires leading from the power transformer?
Black Paint got the PT from Amplified parts. I notice they are all coming that way now.
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If the twisted pair is indeed wall voltage, and untwisted black and white are PT primary, do this.
Disconnect and throw away short black wire that is going from fuse to switch in pic.
Disconnect untwisted white wire from switch, attach that to newly opened fuse location.
Now you have ;
black and white twisted pair to lower 2 switch tabs.
Short white jumper from switch to fuse tab 1.
White PT primary wire to fuse tab 2.
Black PT primary wire to top switch tab.
I will try this now. TY!
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If the twisted pair is indeed wall voltage, and untwisted black and white are PT primary, do this.
Did not blow this time. I am going to hook the secondary back up now see what happens. Nothing lit up.
Disconnect and throw away short black wire that is going from fuse to switch in pic.
Disconnect untwisted white wire from switch, attach that to newly opened fuse location.
Now you have ;
black and white twisted pair to lower 2 switch tabs.
Short white jumper from switch to fuse tab 1.
White PT primary wire to fuse tab 2.
Black PT primary wire to top switch tab.
I will try this now. TY!
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Thank everyone for your contribution. I am getting tired now a product of being little lazy during the covid 19(84) Orwellian (pandemic) mind control people control experiment..(JK) I will put it away an dwell on it a bit.
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Make it look like this:
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I think that is going to be right since black is hot.
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Thank everyone for your contribution. I am getting tired now a product of being little lazy during the covid 19(84) Orwellian (pandemic) mind control people control experiment..(JK) I will put it away an dwell on it a bit.
A nice dinner of Soylent Green should perk you right up. :icon_biggrin:
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No lights or noise, but I am not blowing fuses...... "Soylent green are people!" :icon_biggrin:
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I got it to light up . I found a turret I was grounding out against a screw. But I have no sound.
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The Amp is now playing, but only one side. The Vox AC15 side plays, but is distorted not bad but does not sound like an Ac 15. When I flip the switch to the middle it gets a big hum and all the way over to the Marshall side nothing. I will have to check it later but my power tubes seemed hot and the rectifier was also. The preamp tubes were cool.
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The Amp is now playing, but only one side. The Vox AC15 side plays, but is distorted not bad but does not sound like an Ac 15. When I flip the switch to the middle it gets a big hum and all the way over to the Marshall side nothing. I will have to check it later but my power tubes seemed hot and the rectifier was also. The preamp tubes were cool.
Using your R-meter, check for DC-continuity between the chassis and the ground leads of your filter cap grounds- both for the Marshall channel and the filter cap at the junction stage (PI node?*) of both channels. You may have missed one or more ground return hookup wires.
*guessing in the absence of a schematic
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Thanks Tubeswell I will do that Sunday.
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I had a little wire flag sticking out on my volume I could not see. grounded on the grounding bar above the volume pot . I got rid of the flag and both sides started working so played the Marshall side and flipped back and forth, after a couple of tries the Vox side stopped playing. Oh well divide and conquer.
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I made a rookie mistake and turned the volume all the way down on the AC 15 side and left it down.The amp is upside down on my bench and I have to reach over to mess with things. Both sides are working. I am just going to plug straight into the wall and check my voltages.
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I made a rookie mistake and turned the volume all the way down on the AC 15 side and left it down.The amp is upside down on my bench and I have to reach over to mess with things.
Happens to the best of them, your learning fast. :icon_biggrin:
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Make it look like this:
I hope I told you Thank you.
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Before I finished my Amp and got it playing, my son was real sneaky and bought me a Keely omni reverb and that thing is awesome. I came home yesterday from memorial day festivities and there was a package on my front step. I did not know anything was running for the holiday.
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Nice! :icon_biggrin:
Good son! :icon_biggrin:
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Yeah he really is a Good son!