Paia Gator help - SOLVED

[John R]

Another day, another hum/buzz box. I was trying this concurrently with the Prescription Experience to see which worked better. Turns out... neither. Just a low buzzy hum, which varies as knobs are turned. No guitar sound at all.

http://tagboardeffects.blogspot.com/2016/10/paia-5730-gator.html

All gaps are xactoed, and checked with voltmeter.



Here they are with the layout overlaid -- looks to me like all the components and cuts are in the right place:



I tried several ICs in each spot. Here's voltages:

Wall wart: 10.52

LM308
1 12.38
2 6.59
3 4.38
4 0
5 0
6 6.59
7 13.05
8 6.63

TL074
1 11.8
2 11.47
3 11.47
4 13.05
5 11.46
6 11.46
7 11.02
8 11.92
9 11.22
10 11.47
11 0
12 11.46
13 11.47
14 11.44

13700
1 11.45
2 11.47
3 11.46
4 11.29
5 11.47
6 11.92
7 11.47
8 11.91
9 11.13
10 11.49
11 4.49
12 11.43
13 10.98
14 10.98
15 11.49
16 11.49

seems odd that nearly all the voltages on the last one are about 11v, but there is no ground connected to it, that i can see anyways.

Thanks in advance for the help.

John

[Zanius]

Maybe it's too early in the morning for me, but... what?

10.52v at input and then 13.05v and 11.46v inside the circuit?

I suppose you are using a generic wall wart with different voltage outputs, which is bound to generate problems at some point. If you measure the voltage before connecting it to the circuit it will probably be something around 14volts. Some circuits will work on higher voltage but others won't. I suggest you start testing your circuits with a 9v battery before anything else, that eliminates any problem that can be caused by the "supply" factor.

[Travis]

I'm pretty sure I see a LM13700 pin that isn't soldered in. Looks like pin 1

Without pin 1 of the LM13700 soldered in you won't get any output

I see some other solder joints where there is solder around the hole but apparently not covering the hole or possible component leg. I would go through and touch up all of those suspicious solder joints, making sure that my soldering iron is touching both the component leg and copper strip at the time solder is applied for a reliable joint

[Travis]

Here's a screenshot of one of the suspicious solder joints so you can see what I mean

[John R]

wow, good eyes!! That #1 peg on the 13700 was indeed unsoldered, and I found two more wires poking up that i'd missed. That did the trick! It's working, and working beautifully. Now I can do the volume swell synth parts in Voices Carry and What are Words For, no synth player required. :)

thank you so much!

John

[Travis]

Nice work John! Enjoy