Need help debugging a PR trem

[Luthierwnc]

Bad cap. The first .01 after the .02 coupling cap. It tested OK for both capacitance and DC but when I heated the joint to unsolder it, the lead pulled away from the body before I even touched it with the needlenose.

The three mods (attached schematic) I got off the net I don't know how long ago all increase the trem strength.

Many thankings! Skip

[Phil_S]

Very happy to hear you found it!

[Luthierwnc]

That's why I wasn't too hesitant to rip out that section of the board. Sometimes I wiggle parts or overheat them or pull and replace them to the point that I have to suspect foul play. Occasionally they are just bad on their own but that usually shows when I first test the values. Cheers, sh

[JazzGuitarGimp]

Good news, congrats!

[Deric]

Awesome.

Good job!!!!

[Luthierwnc]

Ready to play, thanks all, sh

[martin manning]

Very nice! Did you try the diode across the intensity pot? I'm curious as to what that sounds like.

[Luthierwnc]

Hi Martin,

I think the main reason for it is to reduce some of the thumping these half-tube circuits get. Mine wasn't thumpy after I got that cap out of there but I left the diode in.

Here is a link to the discussion on that. It refers to a dead link where I got the schematic some years ago -- part of the permanent library so to speak. This discussion works the topic over fairly well even without the original source so I hope it helps. sh

http://www.fenderforum.com/forum.html?d ... ber=445645

[martin manning]

Thanks, that adds some good background info. I was wondering if there is any difference in the character of the effect due to the half-wave shape. You could also use a Zener (12V or so) to limit the negative swing and get more of a square wave. You could try that out by paralleling a Zener across the existing diode.

[tubeswell]

I've used the diode on the intensity pot too. It improves the trem action quite markedly