JLM AUDIO

Followup: Thanks Joe for all your troubleshooting help and testing info. After I corrected polarity on the Opamps, LEDs and related fallout, everything finally tested good. Also very happy to learn about Plugin Doctor to look at the EQ curves of JLM hardware and other plugins. The EQ’s sound and loo...

Hello Joe, I just completed my first of two Audio Path PCBs. Per the build guide, I went to test it, inserted the two jumpers, connected it to an extender...and when I powered on my rack, the two 4R7 resistors instantly fried. Any troubleshooting tips?

Fantastic! A little spray of pot cleaner did the trick. Both comps are calibrated and ready to go. Thanks so much for the troubleshooting help! Now I'll dive into building my FREQ500 kits.

I think something may be grounded on the pot pcb on the faulty comp? When I disconnect the ribbon cable on the pot pcb and measure resistance from any lead to the case, I get readings. If I do the same on the good comp, I don't. When the ribbon cable is connected, if I measure resistance from any po...

Resistor readings matched on SC pcbs for both comps.

SC pics

Great, here's some pics of the SC pcb.

Ok, I swapped the BIO500T pcbs (not transformers) and the high level stayed with the faulty comp.

Ok, the Threshold pot measures 93k and Makeup pot 9.7k. Similar on other comp.

Ok, here are the pics. Hopefully, lighting is OK.

Yes, both comps output level is the same as input level when switched to off.

No, one of the comps output level does not stay the same when switched to VU/GR. It has more output when switched to VU and GR.

Hello Joe, I recently went to check calibration on my two LA500A comps and discovered an input level issue. They were built from kits over 5 years ago. I connected to an extender and from my DAW, setup a signal generator plugin to send 1k tone at -18db and set the send level at -4db. On one unit I h...