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Millett amp problems...big problems - Page 2

post #16 of 24
3/23/04 at 2:30am
I'm thinking it's as simple as a solder bridge somewhere.
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post #17 of 24
3/23/04 at 2:39am
Thread Starter 
The think only possible place for a solder bridge is with the buffer, and I dont see any. I dont really know how to work my dmm, so I have put it on all kinds of setting and just start touching the probes to things...so far nothing.
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post #18 of 24
3/23/04 at 2:57am
The most obvious first thing to look for is whether there's a short from V+ (the traces that carry the power) to ground. If you can't figure out how to set your meter for continuity testing, just set it for the lowest resistance measurement and probe V+ and ground. If it says zero or whatever your meter does for direct connections (possibly two dashes on the display), then you have a short there.

Also, you wired the tube sockets off-board, right? Do you think there's any possibility you wired the tube sockets wrong? (e.g. got two wires mixed up?)
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post #19 of 24
3/23/04 at 3:19am
Thread Starter 
I think I found the continuity setting on my meter. It looks like this 200/.))) . Whenever there is an electrical current can be made, it beeps. I can touch the probe from v+ to any metal or solder joint on the board and get a beep. I dont know what the hell that means but I bet its bad. Thanks alot for this though Wodgy, your the man.

Thanks, Colin
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post #20 of 24
3/23/04 at 3:46am
Thread Starter 
Alright, I definitely have some shorts. I actually looked at the schematic while testing, and at the very first test point I got a beep. When testing d2 (transient suppressor) towards the ground and at the v+ signal I get a beep. Every other ground I tested I also got a beep. These tests were done on some random caps. I do not know if these shorts are caused by the original short (Which I think is the at d2). But, I would like to know how in the world I fix this.....anyone?

Thanks, Colin
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post #21 of 24
3/23/04 at 4:56am
Actually, I just tested mine and it seems like what you're getting is normal. (I'm not familiar with how transient suppressors work, so I'm not sure how to explain that.) Is there any chance you mounted the transient suppressor in the wrong direction? On the PCB there's one end that's a thick white line, and you have to orient the transient suppressor so it matches.
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post #22 of 24
3/23/04 at 11:10am
Thread Starter 
its in the right direction.
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post #23 of 24
3/23/04 at 11:15am
You might want to email Pete Millett and see if he has any suggestions.
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post #24 of 24
3/23/04 at 2:06pm
It's not very efficient to check for shorts on the with the beep mode. You need to set the multimeter on the lowest ohms scale to determin if there is a short or not. That will tell you what degree of a short it is. A 3-10 ohm short may be a bad opamp or other IC. A dead short could mean improper wiring or a solder short or a blown component.
In your case, something sparked and you are not getting any power so that could mean an open circuit somewhere. There are only two ways to find that:
ohm out the whole circuit (hard way) or power the circuit up and check for each of the vital voltages (easier way). Remove the tubes and opamp before you do that and be careful not to short things out. If that checks out, put the opamps back first and check for trouble with their inputs and output pins. Tubes should go last.
If you don't know troubleshoot this you should get someone who is experienced to help.
If you can't eyeball the trouble, you either have to TRACE out the voltage or resistance paths to find the problem.
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