Fuse popping...

Colonel_Sanders · 06-08-2008, 10:24 AM

Hey guys,

Tested my build with only preamp tubes installed and that seemed to work fine. I wired up the OT, everything was still working, then I tested voltages on the power tube sockets, noticed VS was at ground (haven't installed power tubes as of yet). I shifted the connection to the B+ line and my fuses started popping. Even when I put it back to ground, the fuse still pops.

Any tips on how to troubleshoot for the culprit?

So far I've unplugged the preamp tubes, OT, and have checked the PS/PT wiring. Still popping! Need some kind of tube amp diagnostic software

.

EDIT: Schematic's coming ASAP.

Cheers,
C_S

Rob Mercure · 06-09-2008, 02:21 AM

Your issue sounds like simple miswiring or a solder glob short. But what is "VS?" Do you mean the voltage to the screen grid?? If so this is "g2" - grid two - and you would refer to it as "vg2" or "eg2" (electromotive force). So are you telling us that your screen grid voltage is shorted to ground somewhere? What type of output tubes are you using and what value of screen grid resistor? What level of voltage do you expect to be there?

Rob

Colonel_Sanders · 06-09-2008, 02:27 AM

Hi Rob,

Yes, by Vs I was refering to the screen voltage. Cheers for the info. I've just found the problem, loose screw shorting the B+ to ground. Was a bit tired last night

.

Thanks,
C_S

EETStudent · 06-09-2008, 09:47 AM

Oh man, if only I could have back those long, careless 4 in the morning sessions. Plenty of shocks, sparks, and loose material.

06-08-2008, 10:24 AM	#1
Colonel_Sanders Member Join Date: Feb 2008 Posts: 65	Fuse popping... Hey guys, Tested my build with only preamp tubes installed and that seemed to work fine. I wired up the OT, everything was still working, then I tested voltages on the power tube sockets, noticed VS was at ground (haven't installed power tubes as of yet). I shifted the connection to the B+ line and my fuses started popping. Even when I put it back to ground, the fuse still pops. Any tips on how to troubleshoot for the culprit? So far I've unplugged the preamp tubes, OT, and have checked the PS/PT wiring. Still popping! Need some kind of tube amp diagnostic software . EDIT: Schematic's coming ASAP. Cheers, C_S Last edited by Colonel_Sanders; 06-08-2008 at 10:34 AM.

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06-09-2008, 02:21 AM	#2
Rob Mercure Lifetime Member Join Date: May 2006 Location: Wise, Virginia Posts: 624	Your issue sounds like simple miswiring or a solder glob short. But what is "VS?" Do you mean the voltage to the screen grid?? If so this is "g2" - grid two - and you would refer to it as "vg2" or "eg2" (electromotive force). So are you telling us that your screen grid voltage is shorted to ground somewhere? What type of output tubes are you using and what value of screen grid resistor? What level of voltage do you expect to be there? Rob

06-09-2008, 02:27 AM	#3
Colonel_Sanders Member Join Date: Feb 2008 Posts: 65	Hi Rob, Yes, by Vs I was refering to the screen voltage. Cheers for the info. I've just found the problem, loose screw shorting the B+ to ground. Was a bit tired last night . Thanks, C_S

06-09-2008, 09:47 AM	#4
EETStudent Senior Member Join Date: Nov 2007 Location: Columbia, SC Posts: 341	Oh man, if only I could have back those long, careless 4 in the morning sessions. Plenty of shocks, sparks, and loose material.

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