Good amp gone quiet - Troubleshooting Thread...

[MCK]

Yikes, I left my Express build alone for about a year (long story, in between places, stored up etc) and fired her up today only to find I get no sound.

Fuse check ok.
Quick tube swaps yielded no change.
I pulled her out and started voltage checks with no tubes installed and first off...

Edit. Heaters check off. 6.7VAC.

Continuing with voltage checks.

[MCK]

1K 25W dead. Thankfully I had a spare on hand. Popped it in and the amp is breathing fire again...

That is one chunky component so all the TLC from storage workers must have killed it...

I am tempted to glue the new one in with silicone or something but I recall reading about the need to leave some space under it for cooling. Not sure how being gooped in would work for it...

Any ideas on whether or not to secure this large resister in? I'm concerned all that weight being supported only by the two thin leads.

[LeftyStrat]

You could always take some clipped leads from another part and double the existing leads with solder. You can also get these that mount to the chassis:

http://image.made-in-china.com/2f0j00tv ... 0W6RJ-.jpg

[MCK]

Thanks for the idea. The one I used looks like this (just linked to that photo for example. I know its not the correct value) :

[img:250:187]http://2.imimg.com/data2/VN/NL/MY-37472 ... 50x250.jpg[/img]

Any concern changing over the metal encased version above? Given this is in the power supply there should be minimal (if any) impact on tone right?

[MCK]

And its so nice to have my amp back. So happy that the issue was not a tough one to resolve.

[LeftyStrat]

Thanks for the idea. The one I used looks like this (just linked to that photo for example. I know its not the correct value) :

[img:250:187]http://2.imimg.com/data2/VN/NL/MY-37472 ... 50x250.jpg[/img]

Any concern changing over the metal encased version above? Given this is in the power supply there should be minimal (if any) impact on tone right?

I used the same thing in my Express build. But when I get around to doing a Liverpool, I'm planning on using some of those and dumping the PS cap configuration in favor of something like the Dumble PS cap board.

I'm sure some purist will say the metal-encased resistors don't sound the same, and I imagine there are differences in inductance at very high frequencies, but it's nothing a fifty dollar capacitor couldn't cure

[MCK]

Ok. I'll order the metal encased 1K25W and keep it on hand for this one too will break one day I'm sure. That and the $50 caps...

Erm... Anyone have a Mouser or other source link for one of these? Google is not playing nice with me somehow...

[LeftyStrat]

Ok. I'll order the metal encased 1K25W and keep it on hand for this one too will break one day I'm sure. That and the $50 caps...

To go with those expensive caps, I have some fine threads to sell you:

http://en.wikipedia.org/wiki/The_Emperor's_New_Clothes

[rock_mumbles]

Here's an
Arcol from Mouser

[MCK]

Thanks much. Appreciate the link.

$3 for part, $20 for shipping... Ouch. Means I will have to buy more parts to make the $20 shipping charge worth it. Here comes a new amp then!!!