Build Your Own Clone Message Board

I built this a couple years ago and decided to come back to it, as it's been sitting in my garage gathering dust. LED comes on, signal is passed in either state, no effect when engaged. As recommended in a previous thread (https://www.byocelectronics.com/board/viewtopic.php?f=20&t=60124) I measured the voltage at each pin on the four ICs. You can see there are some aberrant readings:

3102:
1 = 7.76
2 = 3.66
3 = 0
4 = 3.68
5 = 7.17
6 = 3.86
7 = 3.77
8 = 3.76

3205:

1 = 0
2 = 3.63
6 = 7.3
7 = 6.76
8 = 7.20
9 = 8.18
13 = 3.64
14 = 8.3

571:

1 = 1.08
2 = 1.8
3 = 1.8
4 = 0
5 = 1.8
6 = 1.8
7 = 2.87
8 = 1.8
9 = 0.5
10 = 1.8
11 = 1.8
12 = 8.34
13 = 1.8
14 = 2.98
15 = 2.98
16 = 1.8

4558

1 = 4.12
2 = 4.14
3 = 4.17
4 = 0
5 = 8.31
6 = 4.14
7 = 4.13
8 = 4.09

These were taken with a new battery measuring 9.1 V. Clearly something is wrong. Any help or suggestions appreciated. Thanks!

You haven't reported your voltage results with the correct pin numbering--the second half of your pin numbers for each IC are in the reverse order. For example, what you report as 5-6-7-8 on the 8-pin IC's are actually 8-7-6-5. Take a look at the pin numbering on the IC image in that posting that you linked, and you'll see what I mean. Accounting for that systematic discrepancy in your reported voltages, the results are actually very normal looking. Good news!

I think I see your problem, though. You have all four trimpots installed in the wrong positions. The Repeat should be the "104" (100K) pot, the Clock should be the "105" (1M), and the Cancel and Bias should both be "103" (10K) trimpots. Correct those placement errors, reset the trimpots to the center position of their sweep arcs, and redo the trimpot setting procedure described on pp. 25 - 28 of the instructions.

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

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

Well I got the trimpots out but destroyed at least a couple of them in the process. The Bourns 3306 Trimpots for sale on the main page will substitute, correct?

Hopefully the damage was restricted to the trimpots and not the PCB eyelets (which can be repaired but is something of a PITA).


Yep, exactly.

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

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

Well whaddya know putting the correct components into the PCB did the trick. Is the lesson here to not drink beer while you build pedals? Nah that’s no fun. But maybe stick to light beer!

Thanks for all your help!

Just stay away from those double IPA's and Belgian abbey ales!

Yeah, isn't it amazing how much better these circuits work when you put the right component in the right place? Glad to hear you got the pedal running.

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

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