HT fuse

[racko7566]

Hey guys, whats up? Question for the minds. I did search first but my problem is my HT fuse blew when I went to the bathroom, all power tubes are light proper color, was biased right, and all pre amp tubes are lit but no sound. I turned it on after seeing burnt HT fuse and checked bias in play mode and the reading was 0, actually 00.01. Any Idea what went?
Thanks.

 

[Jonathan Wilder]

Hey guys, whats up? Question for the minds. I did search first but my problem is my HT fuse blew when I went to the bathroom, all power tubes are light proper color, was biased right, and all pre amp tubes are lit but no sound. I turned it on after seeing burnt HT fuse and checked bias in play mode and the reading was 0, actually 00.01. Any Idea what went?
Thanks.

More than likely a power valve. Just because the heaters in the valves are lighting up doesn't mean they're any good. If the internal elements of the valve short they will take out that fuse. That's mainly why it's there...to be the "sacrificial lamb" that protects shorted valves from taking out other vital components.

Remove the power valves from the amp, replace the HT fuse and see if it blows. If it doesn't, shut if off and reinstall the power valves and power it back up. If the fuse blows this time, it's definitely valves.

If it blows without the power valves installed, it's something in the amp circuit that shorted and will have to be troubleshot further.

 

[thrawn86]

Hey guys, whats up? Question for the minds. I did search first but my problem is my HT fuse blew when I went to the bathroom

Whaaaaa? Like when you flushed? Clue me in here buddy!

 

[racko7566]

More than likely a power valve. Just because the heaters in the valves are lighting up doesn't mean they're any good. If the internal elements of the valve short they will take out that fuse. That's mainly why it's there...to be the "sacrificial lamb" that protects shorted valves from taking out other vital components.

Remove the power valves from the amp, replace the HT fuse and see if it blows. If it doesn't, shut if off and reinstall the power valves and power it back up. If the fuse blows this time, it's definitely valves.

If it blows without the power valves installed, it's something in the amp circuit that shorted and will have to be troubleshot further.

Thanks Jon ill try that out and update after.

 

[racko7566]

Whaaaaa? Like when you flushed? Clue me in here buddy!

I probably splashed my amp when I was hosing Shelly's hoof prints of my a$$.

"Long story, her and Marty broke up.

 

[racko7566]

Update Jon, I replaced the ht fuse and powered up with no powertubes in and the fuse held, then I put them back in and powered up and the fuse held again. I played for a couple minutes and it seemed fine. could the fuse just have been the weak link, or do you think I should shit can the tubes?

 

[Jonathan Wilder]

Update Jon, I replaced the ht fuse and powered up with no powertubes in and the fuse held, then I put them back in and powered up and the fuse held again. I played for a couple minutes and it seemed fine. could the fuse just have been the weak link, or do you think I should shit can the tubes?

Hmm...tough to say. Fuses do actually wear out over time. Every time you power the amp on there's an inrush current as the caps pull current to charge up. That fuse wire flexes to some degree every time that happens so enough times of that the fuse wire eventually breaks.

However...was the glass on the fuse burnt? If not I'll bet that's all it was, but if it was burnt I would definitely suspect an intermittently arc'ing valve. If you haven't replaced your valves in awhile I would definitely consider it.