resistors that go to ground by the pilot lite.what value???

[sidehatch]

I was messing with tubes earlier today and checking plate voltage and created a short and burned theose two resistors up.

They are the ones that go to ground right before the pilot light.

Does anyone know the value of those? You cant read them because they are completely burned up.

When it first happened the amp still worked. I played it some more and they completely burned out and took the fuse with it.

I've looked around a bit and cant seem to find which values to use.

Camera isnt syncing with computer for some reason. if I can get it going I'll add photo's.

Thanks

[bigmik]

if it's what I think your talking about those would be the two 100 r resistors that create a virtual center tap for the 6.3 v heater winding ,are they actually connected to the pilot light?

[Blindog]

Sidehatch,

Here is a link to a layout for a Pro Reverb, should be close to what you have if yours is early '70's. You can see the 2 100ohm resistors near the pilot light. Just unsolder the fried ones and replace them, noting how they were connected before. 1/4 watt should be fine. I don't mean to be insulting, but please exercise extreme caution. Unplug the amp and make sure the filter caps are discharged before doing any of this! You don't want to be the next casualty!

http://www.thevintagesound.com/ffg/sche ... layout.gif



Mark


Edit: I meant 1/2 watt. Thanks Bob!

[Blindog]

double

[sidehatch]

Thanks!!

We are talking about 100ohm and not 100k ohm right?


I have 100k ohm.

Is this a nessesary resistor or a fail safe kinda thing?

Im asking because my soldering iron wont melt the solder on the chassis. Im sure there isnt a problem with the amp and its just something stupoid I did to fry them.

I might have to get a bigger iron.

[tubeswell]

yes - those heater 'virtual-ground' resistors are 100 Ohm. (Not 100k)

[sidehatch]

OK . Thanks.

I'll run by Radio shack and get some tomorrow.

What is the highest value I could use if they dont have 100 ohm or does it have to be 100ohm exactly?

I hope my Iron will melt the solder to the chassis.

Does it matter which way the resistor is oriented when installed?

I cant tell which way because they are burned to a crisp.

Thanks!

[Bob-I]

OK . Thanks.

I'll run by Radio shack and get some tomorrow.

What is the highest value I could use if they dont have 100 ohm or does it have to be 100ohm exactly?

I hope my Iron will melt the solder to the chassis.

Does it matter which way the resistor is oriented when installed?

I cant tell which way because they are burned to a crisp.

Thanks!

You should stick to 100 ohm. If you can't find them at Radio Shaft go to one of the on line stores and order some. http://www.tubesandmore.com or http://www.mouser.com will be able to supply you. Get at least 1/2 watt, I prefer 1 watt because they're larger.

Orientation doesn't matter. You can attach the new resistor to the wire from the old one that's sticking out of the solder blob on the chassis. There should be enough wire to twist the new resistors onto. Soldering to that chassis is next to impossible.

[Jana]

they don't have to be 100 ohm exactly. Anything between 68 ohm and 220 ohm should work just fine.

[sidehatch]

I think I messed up.

I didnt give myself anthing to clip to when I removed the old resistors.

I dont know what I can do to get these new resistors to attach to to chassis.

[Bob-I]

I think I messed up.

I didnt give myself anthing to clip to when I removed the old resistors.

I dont know what I can do to get these new resistors to attach to to chassis.

Not a big deal. Get some of these at a hardware store. [img:300:225]http://www.therm-x.com/assets/5/spade%20lug.jpg[/img]

Slip it under the transformer mounting bolt and solder the resistors to it.

[sidehatch]

*EDIT* Got it working and all is well.



You are the man Bob!!!

Why didnt I think of that?

Thanks all for the help!!!