Messages

Surprised at the Mojo Vibe as there could be a Harbinger in that spot.

Well, I've built quite a few Univibes but I had the MV first Plus, I won't pretend like it isn't the best sounding Vibe I've played! Still, I have more than enough gear to fill a couple more pedalboards so a Harbinger One or Two is likely to be on them.

With my Pedaltrain now permanently occupied with 1590G pedals, I decided to put my old Gorm board back together. Still a work in progress. I think I will add a volume pedal and I'm going to build that little three switch controller for one of the Strymons. Also thinking of a little box to plug that controller and the expression pedal into with a couple of switches so I can easily re-route which Strymon pedal they control. Not much DIY on this board but man it has teh soundz. It's pretty ridiculous.

Signal chain: noise gate - tuner - pitch fork (may move this to after dirt) - a mini Clusterfuzz I made - Third Rail - Ditto - Mojovibe (just found out this one has a bad switch) - B9 (not playing well with the PP2 for some reason) - Mobius - Timeline plus the expression pedal.

Yeah, R19 needs to be 2k. Please double check that (or tell us the color bands on it). Can't really comment on the over-voltage w/o your actual voltages listed.

Well, I don't know what that means exactly. I do know people to use synths/keyboards with EHX Memory Man (seen it plenty of times) so I'd need a little more clarity in what you are after.

No, I don't think your chips are fried. Are you getting the low readings on pin5 with all the other IC's installed or have you tried removing them and just taken a reading from the LT1054?

It sounds really good. I cranked the gain all the way up yesterday and it got me pregnant.

This is the most hilarious amp-related comment I have read.

Although the NF should work at +12v I would start with 9v (which is the standard). I don't think that is the problem here but always eliminate every possibility.

Are you positive you used an ON/On/On switch for the LP/HP/BP?
Your voltages look pretty good although pin7 of IC2 is a bit high (again, could be from using a 12v supply instead of 9).

C5 and C6 are the two DC blocking caps here. So, it would be one of those if you are reading DC at the output. If you are adept at desoldering then try removing one of them (doesn't matter which) and re-measure to see if you are still reading DC at the output. If not, the cap you removed is the bad one. If so, then one or both caps are leaky.

.3v is not insignificant...if it were 0.03v I would call it ground, but what you are describing is problematic. The other solution (if you don't want to desolder those caps and potentially damage the PCB) is to add a larger electrolytic (like 4u7 or 10uF) between the FX output wire and your 3PDT switch (negative end to the switch). That would eliminate the leaking voltage and be large enough not to affect the AC signal coming through.

Okay, this is how you diagnose and fix this problem (relating to the Rustbucket although the process is the same for the Freekout). It sounds labor intensive but it will actually only take about ten minutes. As Jon stated - you need to find the current sink and if there is more than one. Skip any steps you have already done.

- Remove all IC's from their sockets.

- Power the board, and verify +15v from the regulator.

- Un-power, replace the LT1054 in its socket and re-power (do the un-power and re-power for each subsequent step). Verify you have -15v from pin5 of the LT1054 and +15v from pin8. If you do not, then you need to re-flow the solder joints on all the ICs and/or replace with a different LT1054. If you do, then you know each IC is getting proper power (because any one IC that had a solder joint or PCB error on the power rails would show up at this step).

- Here's the meticulous part - you need to start populating one IC at a time, check for +/-15 volts on the proper pins and check if the LT1054 is getting hot (both are likely to happen at the same time). Do it in this order: 4558, LM741, LM1458, CD4047, CD4013, CD4066, LM311, CA3080 and finally the MN3007. If at any point in this process you are not getting the proper +/- voltage or the LT1054 is getting hot, you know you probably have an IC that needs to be replaced. You should do it for all ICs - don't stop if you find one bad one (because you need to know if there is more than one problem area). It sounds like a lot of work but trust me, I've done this sort of procedure plenty and it doesn't take long.

Report your findings for further assistance if needed

The Mimik doc was missing the LM78L05 regulator from the BOM and shopping list. This has been corrected in the pdf.

Is there any downside to raising the input impedance?

In this specific case, I don't think so. It will lower the maximum gain you can get with the Level control but it will still break up quite a bit. Series resistance can increase the noise floor so increasing the input resistor from 100k to 220k might have a very slight effect, but I bet it's well under the total noise floor of the entire pedal so it won't matter. It's easy enough to socket and A/B the two values with a humbucker guitar and see if it makes any difference for you. More to the point - your options for cleaning up the DMM are pretty limited. It's dirty, dirty, dirty and that is part of the charm. I guess you could go with some hi-grade low noise op-amps. Never tried anything beyond 4558 and TL072 so I'd be interested to hear your results.

I'm pretty sure one of the upgrades is swapping the input resistor of IC1 to 220k from 100k. This raises the input impedance and can be useful for humbuckers. On the TR, it's R2.

Swapping the 4558s out may improve S/N slightly although I don't think it'll be that noticeable. The DMM is basically a dirty-a$$ analog delay. But, it's easy enough to try and see if you like. Maybe leave IC1 as 4558 for the grit on the Level knob.

I don't know if there are any other circuit changes he does. I know some of it is cosmetic on the enclosures.

Here you go.

The mounting clips are offset from center so they only go in one way. Check the switches against the holes on the PCB and you will see what I mean.

CV suffix is fine for this build. It's the one I used (actually the only kind I have).