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Bypass works. I can wedge a wire under the tip of the input jack and jump to get sound but no distortion from some points, but turning it on with the guitar plugged in gets me silence.
FWIW, it looked a lot better before I started troubleshooting. Freeing a pot to fix a cap proved to be challenging.
The density of the wiring prevents me from making out what you’ve done with the Reutz mod. But I don’t think an error there would prevent the distortion from happening.
You could work your way backwards with signal tracing and start by checking if the center pin of Q1 (2N5459) has the proper signal. If there’s no signal there, check the left pin of Q1 for proper signal.
And in the photo, it appears that C10 may have been melted a bit in the top left corner. May want to dbl-check that too. (If you have proper signal at th center pin of Q1, C10 may be the culprit.
Oh, and as always, please verify that the voltage supply is indeed ~+9v.
Let us know what you find.
Yeah, wish I had laid that out a bit more before I put it together. Or had a good way to get the board mounted before modding. The pot prevented working on that side after that.
Nudged C10’s corner a bit when I had to remove a pot to fix another cap. Will be replacing that for peace of mind if nothing else. It was flawless (relative to my skill level) until troubleshooting.
DMM shows the power supply is indeed 9.26v.
Probing with my wire produces undistorted sound when contacting the left leg of Q1, but nothing from the other two. An occasional little click, possible from contacting the pad. Likely I burned out the transistor?
And FWIW, the switches’ only effect so far is which leg I can get sound from when poking around. On any of them.
And the lower ceramic cap is 100p, the upper is 22p as called by the BOM. The build notes say to use a 30p or 33p with a LM308 chip, which I didn’t catch in my initial reading. I have an LM308N from this shop in it.Sounds like you have toasted the FET. If there is +9v on the Drain of that FET, then it may indeed be bad.
Try #2. Brand new PCB. Made exactly to BOM, oriented to board, quadruple-checked.
Out of enclosure. Socketed FET. No switches and test knobs hooked in to remove variables. Same results.
9v on the drain again. What are the chances I fried one and got a second bad one?
Found a 2n5457 (as noted acceptable in the build doc) to test with and… same results.
IC and JFET are socketed. The only thing that hasn’t been sextuple-checked and brand new is the LM308.
Do have a few OP07s on the way, will test with one of those.So now you’ve built out a second Rat without any mods? If so, from where was the chip acquired? I would suspect the chip if building a 2nd one and getting the same results. Or quite possibly the same wiring error. Wiring errors are the easiest to trip over. Good clear photos of the second build?
That was my thought. It’s a mess, but continuity checks out on all the wires. A couple aren’t pretty and will get reflowed, but my DMM beeps.
The chip was from here so it didn’t strike me as the first culprit. If it is, I suspect it’s my fault; the legs of C3 and C4 are really close and I could imagine the first one shorted them initially.
There’s a possibility the 2n5459s are from Small Bear but I believe they’re from Tayda. That might concern me. I’m not sure a bad one is in line to cause any damage, though. The 2n5457s are from here, but if the LM308 is the culprit, they’re down the line.
I’ll have to track down other proper replacements for the 5459s, the whole 54xx series is getting hard to find reliably.As before, C3 is a 22, C4 is 100p (labelled 101). JFET is currently out, but both 2n5459 and 5457 had legs straight into socket and shape oriented to silkscreen.
During testing, the right LED burnt. Don’t know if I shorted something with the DMM or it was a bad LED. Flat spots on both match silkscreen. No repeat since I’ve been more careful.
Jack runs post to ground, right leg to 9v.
My plan for now, unless something gets pointed out, is to test it with an untouched 2n5457 and an OP07, to remove that variable.
Just waiting on the ICs.Fair enough. I’ve found that there is ZERO advantage to using a 308 in place of an OP07 – they are pin-for-pin and sonically identical.
Good luck!
Update: still waiting on my OP07s and a handful of 2n5458s.
But I checked the build docs, have a handful of 2n5457s and TL071s, and got curious…
And it’s probably not ideal–definitely not full Rat snarl, at least without the diode options–but it’s making sound!So my LM308 is going in the bin. Probably shorted that sometime. Going to box this up, be real careful about soldering everything into enclosure, and figure out some way to reliably keep the JFET from vibrating out of socket.
The other one is getting turned into its clone, probably simplifying my weird Reutz idea, and will be a Secret Santa gift this year for a coworker before his punk band does a spring break tour.
Moriearty – sounds like you have a plan. For socketed parts, other than ICs, I gently ‘wrinkle’ the ends of the legs so they fit quite snuggly into their sockets.
I believe I’ll start doing that. For now, testing the old one shows I didn’t burn anything out. Yay!
So now I have two working Ratts. Coworker will have a good christmas.
Bypass works. I can wedge a wire under the tip of the input jack and jump to get sound but no distortion from some points, but turning it on with the guitar plugged in gets me silence.
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