GGG Rodent Kit assembled but no sound

I've assembled my GGG Rodent kit. I've only measured voltages at the chip so far but here's my voltages there:

1: 8.67 V (should be 8.4)
2: 4.75 V (should be 4.5)
3: 2.38 V (should be 4.1)
4: 0 V (should be 0)
5: 0 V (should be 0)
6: 4.78 V (should be 4.5)
7: 9.61 V (should be 9)
8: 4.87 V (should be 4.6)

So I'm getting power into the circuit (need to poke around more to trouble shoot) but every time I hit the foot switch to turn it on the volume cuts out. Nothing. Is there something quick and obvious that I'm missing? I should be getting SOMETHING.

Picture:

http://farm4.staticflickr.com/3695/1...09bc6531_c.jpg

I think your transistor is backwards? I think it should match the outline on the board.

I tried both ways. That's not it.

Bad transistor, maybe?

Maybe? It's a makeup gain stage, fyi. I would bypass the switch and see if you get any signal. The switch looks right to me, but I'm not familiar with that way of wiring it. I use a different scheme. Cut down an IC socket to use there, I do that cuz I've fried some trannies in the past. Try another Chip too, can't hurt.

Also, this is where an audio probe comes in handy, it's saved my bacon a couple times!!!

How do you bypass the switch? And that is an IC socket in there. The chip is in the socket

A signal probe would make short work of finding the problem. A probe is nothing more than a capacitor, some wire and a small amp so you can hear the signal as you trace it thru the circuit.

Can you buy a signal/audio probe?

You could make one out of a 1uf electrolytic cap and an old instrument cable you don’t need. Cut off the plug at one end and strip back some of the insulation. Solder the cable’s center conductor to the negative lead of the cap. The positive lead of the cap will be the actual probe. Solder some extra wire to the shield (ground) of the cable to ground it to the pedal. The sleeve of the input or output jack is a good place to ground the cable/probe assembly. Plug your guitar into the pedal’s input and plug the plug end of the probe cable into the amp. Actuate the stomp switch and strum the strings of the guitar and touch the + end of the cap to different points along the signal path thru the circuit. When you get to the point where the signal dies go back from there to look for the problem. It might be a poor solder joint, a misplaced resistor or a solder bridge shorting the signal to ground.

Is C10 in the correct two holes?

I think we may have a winner. Just took a look at the pix on the GGG web site and it appears that you have C10 on the wrong holes.

I'd make sure you flip the transistor around too if you haven't already.

Dang. Good catch Don! I'll fix that tonight.

I should have the little notch in the chip the same way the (etched) notch in the PCB is pointing. I'll double check when I get home.

That was just a guess. I looked at the pic and wondered what I'd be most likely to do incorrectly (besides what was already mentioned).

I agree that the transistor looks like it's backwards as well.

I'll swap the transistor when I get home too.

I use cut down IC sockets to socket transistors. That's what I meant, I see I wasn't clear in my post.

And to bypass the switch I take the board and wire it straight to the Jacks.

But, I don't think you have to do any of that. C10 & the transistor and you should be up and rocking!

AND WE HAVE ROCK!! :dude

Thought I had burnt the transistor. Took me forever to work it out (my desoldering technique isn't the best; especially with three prongs). The LED doesn't work but beggars can't be choosers.

I also just noticed that I did get the labeling backwards on the volume and distortion knobs. :laughing:

Great news!

It sounds like a JCM 800 in a box. It's a good compliment to my Mojo Hand Mule.

I love my RAT, works good on bass too! I'll bet you wired your LED backwards... I STILL do that from time to time.

Probably. I may fix it after thanksgiving. A little distortion definitely goes a long way with a Rat.

OK, now we sort-of have rock. Last night it performed flawlessly. This morning it was very "blatty". It would only make sound when I hit it hard, when the sound would "cut in". Then for a few minutes it worked but only at full tilt. The knobs wouldn't adjust anything. Then it got "blatty" again. This was with humbuckers. Then I plugged in my tele and it worked fine for a few songs so I switched back to my PRS and it worked fine for a few songs, then it got blatty again and started cutting in and out.

Any quick and easy suggestions before I troubleshoot next week?

Are you using a battery? Is the battery dying?

Yes I am. It should be a new battery but I'll change it next week just in case.

If the battery is good then the problem is probably a cold solder. Let's hope it's the battery!

Check out the solder joints on the power connector.

If a battery change doesn't work I'll check that first. Thanks Don and Chuck!

Are these the ones that sound best with the cheap radio shack batteries rather than the alkaline?

I thought that was Fuzz Faces and certain other vintage fuzzes?