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PostPosted: Sat Jan 21, 2023 11:55 am 
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Joined: Sat Jan 21, 2023 10:32 am
Posts: 3
I have been troubleshooting this project for several weeks and tried many of the helpful solutions already posted here (reflow, etc) that helped at different stages.

This is my first BYOC build, but I have basic soldering experience with guitars and through-hole electronics. At one point, I had the pedal working outside of the case. Assembled into the case, the volume was always at 100% despite the position of the pot. Otherwise, it seemed to be working properly as the LED was switching off in bypass mode, and distortion (nice sounding OD) was being produced.

Then, as I was trying to troubleshoot the volume pot, the volume function started to be intermittent (i.e. no volume adjustment possible) even outside of the case. So I assumed that part of the problem was my wires being too long or another problem with the wires due to the frequent bending at the connection when assembling into the case, etc. So I decided to desolder and re-connect all of the pots and power plug with shorter, color coded, wires.

After completing the rewiring step, the pedal now has the following incorrect behavior (outside the case):

-Bypass mode - clean sound from guitar, but LED is on (incorrectly).

-Active mode - LED is also on, but brighter - no sound from guitar with pots at 100%

Also, if the instrument is not plugged in, the LED is off in bypass mode.

Fortunately (?) I had a vary similar problem on my first assembly attempt and realized that there was grounding of the input signal to the case, which was easy to remedy. However, I am now getting this behavior outside of the case. I verified that the input signal is getting grounded when the foot switch is engaged using a continuity tester. But I don't know how to find the fault in the switch or the PCB since there is no obvious way (to me) the input signal is finding ground at the "IN" solder points on the board.

Any help or guidance would be appreciated. Sorry in advance if this is obvious. My PCB pictures are shown below.

wire color coding: red = positive, signal or pin 1., yellow = pin 2, black = negative, ground or pin 3.
Attachment:
LMO_PCB_Front.jpg
LMO_PCB_Front.jpg [ 129.49 KiB | Viewed 1340 times ]

Attachment:
LMO_PCB_Back.jpg
LMO_PCB_Back.jpg [ 139.67 KiB | Viewed 1340 times ]

Attachment:
LMO_Connections.jpg
LMO_Connections.jpg [ 76.56 KiB | Viewed 1340 times ]


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PostPosted: Sat Jan 21, 2023 7:01 pm 
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Joined: Mon Nov 23, 2020 1:39 pm
Posts: 181
Location: Vermont
A few weeks ago there was a build problem with a "Li'l" kit that had similar mysterious behaviors, indicating wiring/continuity/shorts problems, including the LED being on (though fainter) in bypass mode. The builder wrote in the happy final entry to that thread:

"I cleaned off the excess flux (part of my problem), took the footswitch apart, ended up having bad soldering underneath the switch. Desoldered the switch( not recommended). Damaged the board. :? Was able to make a bridge to bypass the damaged pad.
Works!"

It's not exactly clear from this report, but it may have been that there was extra connectivity (shorts) at/near the footswitch pins. Perhaps if too much solder is applied, it can flow into the gap between the switch housing and the PCB and make extra connections. This could account for there being an extra conducting path that allows the LED to illuminate in both switch positions. (Why removing the input plug interrupts that, I cannot say.)

Entirely removing the switch would be a big nuisance, but might be indicated if there appears to be more continuity between the pins than there is supposed to be. You might try, for both switch positions, to see whether there is continuity between pairs of pins not otherwise expected.


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PostPosted: Sun Jan 22, 2023 2:59 pm 
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Location: Albany, NY
Since the pedal is passing clean signal when bypassed, the problem can't be with the input jacks and their wiring to the PCB. Similarly, the bypass route through the footswitch is also OK (more on that below).

Here is a quick drawing I made of the "hard" footswitch connections in the Li'l Modified OD:

Attachment:
mini_pedal_FS_connections.gif
mini_pedal_FS_connections.gif [ 282.79 KiB | Viewed 1314 times ]


The "soft" connections are those made through the footswitch itself. So in bypass, the signal passes from the input jack to lug 4, through the jumper trace to lug 3, then through the FS connection to lug 2 and on to the output jack. Since this path is working, none of these points can be grounding. I would recommend that, with the pedal switched to the engaged position, you check for continuity between ground and each of lugs 1 & 5. If you see continuity to ground from either of those lugs, you probably have a short in the space between the footswitch & PCB due to solder that has flowed between them (this is the most likely cause), or there's a short on the PCB between those lugs and the next components in the circuit (R1 & C1 on the input side; R16 and C9 on the output side), which is far less likely. If you do NOT see continuity to ground at those two lugs, than you either have a signal short to ground on the PCB somewhere, an open circuit somewhere (usually a bad solder joint), or a failed component. So try the continuity testing first and report your findings here.

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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


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PostPosted: Thu Feb 02, 2023 8:00 pm 
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Joined: Sat Jan 21, 2023 10:32 am
Posts: 3
Thank you duhvoodooman and WMP1!

It was pin 5 in the switch which was grounded when engaged as you suggesgted. So I ended up removing 75% of the solder from each pin using a desoldering gun (which hopefully pulled back some of the excess from the opposite side) and then putting a little more solder back on to ensure the connection with the pad. This kept me from destroying the switch and the PCB. This time, I did not completely fill the hole as shown in the instructions, the solder connections are on the short sides of each rectangular pin.

The pedal now operates normally outside the case (LED off in bypass mode). I am now having issues with low max volume in OD mode when fully assembled (the volume pot functions, though) compared to the clean signal. There was another thread on that topic so I will look there. I will also redo the connecting wires to the power jack and the pots using heat shrink at the connections to guard against potential short circuits and see if that improves the situation.

So, I would consider the original issue solved. The lesson is not to overdo it on the solder for the switch connections. This is easy to do because of the large gap for solder to flow into. And it is hard to see the problem because it looks "good" from the side you can see.

Thanks again for the quick and effective responses!


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PostPosted: Sat Feb 04, 2023 12:30 pm 
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Joined: Sat Jan 21, 2023 10:32 am
Posts: 3
Picture of the finished pedal, assembled into the case, working. Adding heat shrink tubing on the wire attachments to the pots & power jack solved all remaining issues after fixing the problem with the footswitch. I'm really enjoying the sound with Bass Guitar and the adjustability of the tone, drive and volume gives a wide range of options from just a nice edge to all out distortion. I applied an inkjet waterslide decal to the plain metal case for the decoration.

Thanks again to all who helped. Looking forward to applying all of the tricks and tips to my next BYOC build...

Attachment:
IMG_20230204_125844099.jpg
IMG_20230204_125844099.jpg [ 49.67 KiB | Viewed 1251 times ]


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