LM13700 causes negative voltage issue [SOLVED]

I am building a LP2 Delay Shruthi. Testing the power supply, the positve voltage was consistent at +5, but the negative was -1.45. I removed all the ICs and have narrowed it down to the LM13700 as the cause. With LM13700 removed everything reads -5V. Just not sure where to go from here.

Any help would be appreciated.


There are two LM13700 on the LP2 Delay filter board. Does the voltage issue appears with both or just with one of them?

It could be a damaged IC, but also maybe a problem with your board (incorrect part value somewhere…). Could you post pictures?

Both of them cause problems and I have switched them out with another chip from a working shruthi and still no luck.

Are you shure these light blue resistors with 2 black stripes are 10K Ohm?

Good question. they came with the mouser order labeled as 10k. Guess I took a chance by putting them in

Well I replaced the wack turquois resistors (Mouser was not helpful in identifying these) with the proper 10k (2% tolerance tho) ones. I am now getting the right -5V readings on both the LM13700 chip and on everything else. I may have damaged a pad or two desoldering the resistors though. Not sure if this will make a difference.

And now the cutoff is not working properly. I can hear the resonance when its turned up, but it certainly doesn’t sound right. Any ideas how to fix this? I can attach photos if that will help.

I have successfully built a shruthi and anushri with no issue, but I have certainly learned my lesson with self sourcing parts.

Have you chosen the right filter in the settings and saved it?

No I haven’t tried that! Where can I find the filter settings?

Press button 5, so that the led above it is off. Then press button 4 repeatedly until you see the “fil” setting and change it with the pot to “dly”. Then save it with button 6 (chose “ok” with the encoder and press the encoder)

Ok cool. Thanks cj55! I’ll try that this evening!

Hot Damn! Everything is working now. Just had to replace those 10k resistors and had an issue with the headers connecting the boards, but now I’m all good.
This filter sound FILTHY, I love it!

Thanks for all the assistance, this community is dope!