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in august I built the mimosa compressor and it worked fine then, but two weeks back it started to make a lot of noise when engaged, and then suddenly it wouldn't pass signal at all. I opened it up and it all looked fine, so I took it apart and redid all of the solder joints. reassembled it, plugged it in and it worked in bypass mode, but not when engaged. realized I left the ic out of it, so I plugged it back in and suddenly bypass didn't work and neither did the engaged mode. any ideas on what could be going on?

Is it possible the trimpot got turned while it was out of the enclosure? Try dialing it back in if you haven't already.

That shouldn't affect the bypassed signal, however. No bypass usually means a wiring error or a short, or possibly a faulty/damaged switch. Do you have a multimeter so you can check voltages and continuity?

Your soldering looks pretty decent from the top side, but it's always helpful to have a photo of the solder side of the board as well.

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Scott

My band, Austin Hollow

Heres the reverse side, I tried to measure the voltage of the trimpot, but it came up zero

Almost sounds like the stomp switch. It should pass audio in bypass, audio comes in, up and over the footswitch and back out. It comes in on lug 4 to lug 9, true bypass goes in lug 4 over to 9 and out on lug 8. Engaged in comes in on 4 to the effect in on lug 5 out of the effect on lug 7 and out to the output jack on lug 8.



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Pedal building is like the opposite of sex. All the fun stuff happens before you get in the box.

I'd be checking the wire connections at the IN and OUT eyelets up at the top of the PCB. Sometimes it's possible to get melted wire insulation down into the eyelet, preventing solder contact between the wire end and the eyelet. Both of those joints look to have melted insulation pushed right up against the joint. Wouldn't hurt to check the two ground connections up there while you're at it.

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

ok I fixed the insulation being pushed up against the eyelets but no luck. any other ideas? replace the footswitch?

If you have a multimeter, we can tell you how test the switch's functionality to see if it needs to be replaced, or if we should look elsewhere to solve the problem.

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Scott

My band, Austin Hollow

Yes I have a multimeter

OK, to check the functionality of the switch, set the meter to continuity check mode. Continuity is the absence of resistance, so, for example, one end of a piece of wire should have continuity with the other end, or all points of the enclosure should have continuity with each other.

A properly functioning 3PDT switch has two "states". In the first, you have continuity between lugs 1 and 2; 4 and 5; 7 and 8. Actuate the switch, and then you have continuity between 2 and 3; 5 and 6; 8 and 9. The lugs are laid out as follows, assuming the switch is oriented so that they are horizontal, as indicated in the instructions.

1 - 4 - 7
2 - 5 - 8
3 - 6 - 9

Other than jumpers you've installed, there should not be any other continuity between lugs on the switch. Check to make sure that this is the case. And if this post isn't clear, let me know and I'll rephrase it.

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Scott

My band, Austin Hollow

Honestly, I would carefully reflow the footswitch. One lug at a time, making sure it is cooled before moving on to the next. The wire on lug 4 and the one on lug 5 look odd and solder starved.


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_________________
Pedal building is like the opposite of sex. All the fun stuff happens before you get in the box.

the continuity test came out perfect. anything else I need to check?

Do you have an audio tester?

I sometimes will also check the continuity from the foot switch to the input and output jacks to see if there is something awry there.

Yep, that's what I'd suggest next. If you're not getting bypass, it's a really simple signal path with no resistance, so you can check the whole thing with just a multimeter. (Let us know if you need us to give you the point by point path.)

Once you get bypass working, if the effect itself doesn't work, the audio probe/signal tester is a likely next step.

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Scott

My band, Austin Hollow

This would be ideal. You can also test for continuity to ground anywhere along your bypass signal path. If that's shorting to ground, nothing is going to work.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Yes, sooty, could you tell me how to test the continuity of the bypass path?

This will sound like a lot but it will take about 30 seconds.

OK, so first of all we need to make sure the pedal is in bypass. Take a look at this diagram of what the 3PDT switch is doing. The guitar signal comes from the input jack to lug 4. As you know from testing it above, one state of the switch connects lug 4 to lug 5, which sends the signal into the PCB. But we're not worried about that state. You want to test the switch in the other state, where lug 4 and 5 are not connected. That's the bypass state. The jumper from lug 4 carries the signal to lug 9, where the switch (if properly working) will have continuity to lug 8, which connects to the output jack.



So here's what to test. Plug a cable into the input and output. Then test for continuity in all the following places, in this order:

the tip of the input cable > the tip lug of the input jack

the tip lug of the input jack > the IN pad near the input jack

the IN pad near the input jack > the solder pad by the foot switch labeled 4

the solder pad by the foot switch labeled 4 > lug 4

lug 4 > lug 9

lug 9 > lug 8

lug 8 > the solder pad by the foot switch labeled 8

the solder pad by the foot switch labeled 8 > the OUT pad near the output jack

the OUT pad near the output jack > the tip lug of the output jack

the tip lug of the output jack > the tip of the output cable

the tip of the output cable

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Scott

My band, Austin Hollow

Ok so I tested everything on your list, and it all checked out ok, except the 1st connection was touchy. So I plugged my bass into it and tested it and it still didn’t work. Nudged the pedal and viola, signal. Turned out that the tip lug wasn’t fully seating on the tip. But as is the way of the universe, now the affected signal doesn’t work when fully blended, back it off by a tiny bit and it works and compresses, but all the way up it drops to nearly inaudible

That sounds like a bad pot.

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Is there a way to test it or should I just swap it out?

Yes, you can measure the resistance between the middle lug and each of the outer lugs. This should vary between zero and ~10 Kohms, depending on the position of the pot knob. If the pot shows a very high/infinite resistance at one end of the sweep or the other, then it's defective and needs to be replaced.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

so I set the multimeter to 20k ohms and both the left and right lugs read between 0 and 6.6

Hmmm, that agrees with what I read on my own Mimosa. Not sure what's going on, I'm afraid.

Just a comment: it's pretty unusual to run the blend all the way to one side or the other, in my experience. Somewhere in the range of 1/4 to 3/4 is pretty typical, I believe. While I agree that the volume shouldn't cut out with the blend all the way CW, I would think that the pedal should be quite useful as is.

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

If the blend knob acts like a reverse volume knob, i.e., the volume cuts out completely when you have it all the way "wet", that means the compressor part of the circuit isn't working. And by not working, I mean it's completely dead, not just not compressing.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

So is there something I need to replace or re-do?

Have you reflowed all of your solder joints? If not, I would suggest that first. If you have, can you post some new pics?

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.