Did you read this?
Here’s the schematic by Rene Schmitz that the LMNC Performance Filter is based on. (Not sure if that’s the filter you’re building though, but if not, similar ideas apply.)
[image]
The control current is supplied by one of the transistors via two 10k resistors, one on each side. For the LM13700 (used instead of the even more obsolete CA3080) these resistors connect to the control current inputs, pins 1 and 16. In the worst case scenario the transistor output is 12 V. To avoid blowing up the LM…
If the circuit is built correctly the control current to the LM13700, which is the main suspect if one blows, should be safe. You need to verify the 10k resistors. Measuring resistances in circuit is rarely useful, but you can at least verify the color codes are correct.
Other than that:
(This is a wiki post, please add and correct!)
Look and see if others have had the same problem. Use the Discourse search facility to find topics where the module you’re building is discussed.
Inspect your work. Verify all components are correct values. Look for solder connections that are rough, irregular, skimpy, dull, or missed completely (we all do that!) and reflow them. Look for solder bridges between pads and remove them.
Check your power connection. If it’s a Eurorack style power cabl…
And yes photos (top and bottom) would help.
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