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Hi All
Got my Tramp kit all built but i must have done something wrong because I keep blowing fuses

i measured the same resistance / continuity at the all three points of the same lug which carries the 6.3 vac heater wires. which doesnt seem correct at all

thought i would post to see if anyone has a good ideas before i tear into it...

ill will post some photos soon mabey someone can point out my mistake(s)

Thnx

The resistance of the heater wires to ground is very, very low. Just make use that the 6.3VAC leads are not connected to ground. And the same with the high voltage leads. A picture would help.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

some photos
hopefully its an easy fix thats been staring me in the face

thnx all

But check that you havent wired up the LED so with one side going to ground. Double check that the heaters dont touch ground.

When you tested the Power supply before hooking it up to the heaters or board was it OK?
Does is blow fuses when the board is hooked up or when the heaters are hooked up? I would disconnect board first and see, then the heaters. Divide & conquer.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Probably not this but I guess it's something to be eliminated, are you using "Slow Blow" fuses to avoid them blowing due to any inrush current at switch on?

thanks for the tips all

gonna start again tomorrow
got a few slow burn fuses left

crossing my fingers

ok so some progress
i disconnected the 630vac red wires from the board and tried again
this time no blown fuse !
so is their a way to reconnect the red 630 vac wires and disconnect further along the circut path ?
to test the next part of the circuit ?

Hmm, could be the MOSFET circuitry. Is the MOSFET insulated from the chassis with the provided grey pad? Can you test that thee is no conductivity from the chassis to it?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

just checked the mosfet
no conductivity there

Just wanted to report that the tramp is alive and working!

Two problems, 1. powersupply cap body was shorting out on the turret and 2. Blown 6v6s tube

Thanks everyone for your help !

That's good news. Thanks for following up.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I know this is an old thread but the topic is what I'm experiencing.

I disconnected the 630VAC wires and the fuse did not blow.

I tested for continuity with the mosfet to ground...the middle pin has continuity whereas the other two do not. The mosfet is on the pad and held in with a #4 screw with a nylon bushing.

All other components seem to be wired correctly and appropriate value. I used compressed air and then a vacuum to get rid of any stray wires clippings. I checked under the board and all looks good.

Should I bypass the VRM and see what happens? If I do this, would I lift the leg of R23,R20 and Z1, and run a jumper from C13 to C12?

I also have an extra mosfet from a Hall Amplification VVR kit I could try as well.

Any troubleshooting help you can give me would be greatly appreciated. Thanks!!!

Something is wrong with the VRM it sounds like. Bypass it to confirm

I'd replace the Zenor diode and the MOSFET. Install a new silca pad if you have one...

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Thanks...I was just updating my post when you replied. To bypass the VRM, would I lift R20, R23 and the zener and run a jumper from C12 to C13?

Yes, that will work.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Ok....did the above and still blowing a fuse. Everything on top of the board looks good..tube sockets, pots, etc are all according to the layout...Something must have happened with the under-the-board wiring.

Yeah, if you are still blowing fuses, check that there is no short to ground. Pull the tubes & retest
Good news is its not the VRM module.
you might want to invest in a light bulb limiter.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks Stephen. Will head to home depot in the next day or two and get stuff to make the limiter and go from there.

Frustrating thing is that I know this has got to be a very simple solution...just need to find out where the problem is.

Alright...I've built a nifty little current limiter...even mounted it on a scrap piece of mahogany (for chunkier tone ). At this point how do I approach the troubleshooting? For example, if I plug the amp into the limiter and the bulb lights up like no tomorrow, what would be the next step?

Right now, I have the board out of the amp and checked all the wiring. I've traced the schematic and all looks good. Sockets, bias resistor switch, OT primaries switch, heaters wiring, mains wiring, etc. all look to be right on. I know something has got to be wrong...probably something stupid.. but at this point I don't know how to figure that out. I believe I have a direct short to ground, but not sure what would be the best "test points" to check for continuity to rule out different areas of the circuit. Also, I'm contemplating doing a complete disassembly of the board and checking each component and reinstalling from scratch.

Any next steps you could suggest would be greatly appreciated.

Thanks again for all your help.

Making progress....
1. removed board from chassis. bolted a 3-lug terminal strip to the chassis and connected the PT 315VAC secondaries to lugs 1 and 3. Powered up the amp...no blown fuse. ~630VAC across the secondaries and about 7 VAC on the heaters.
2. Removed all VRM components from board, and isolated the power amp section by disconnecting C7 from the power rail and removing VR4 from pin 6.
3. turned on the amp and no blown fuse...woohoo!

Next step is to work on the pre-amp section and test again.