JLM AUDIO

Hi Again Joe, apologies for all my bungling! So I decided to put the compressor back together after soldering the dip 8 pins I had missed on the side chain board. Good news is the meter appears to be working well now. the Sidechain NE5322A pin voltages all match the NE5322A on BIO500 board now as i...

You have to measure the 1.23v between pin 2 and pin 3 of the output XLR as that is the balanced out. Otherwise the output transformer is floating and you will just get random meausrements OK as stated previously closest to 1.23vac I can get is 1.224vac. I send this 1Khz sine to FC500A input. In VU ...

OK main thing below is to test if the meter coil is intact. See below I had another good go at all the toggle switch points with the solder iron. Cool Input to JLM Eleven rack measured the 1Khz sine wave at 1.228 volts With rack power off or on and 500A connected via edge connector I measure 1.224 ...

I only have one preamp connected. With nothing connected to the PSU I have 306VDC unregulated and the regulated supply jumps up to 296VDC. Both HV1 and HV2 have the same issue, when the Filament is connected they won't go higher than ~256VDC Ok that is a bit low. Does it go to 320v with no filament...

I found the culprit, not sure how this got checked on or if it is set this way by default in REW but I went back to not using the Y cable and then I unchecked this and the link switch works perfectly. Such a stupid waste of time trying to troubleshoot a problem that really wasn’t there. IMG_6982.jp...

I’ve got the scorpion up and running now with it bolted to a 1/4” bar of aluminum. The heater voltage seems solid, but I’ve got HV2 cranked as high as it will go, and under load it stops at 256V. I’ve got 266V unregulated at the power resistor and 116VAC at the outlet (USA). Does this seem correct ...

OK that looks ok. The clue will be what ac volts you are getting at pin 6 on each IDC 10 pin header on the mac link pcb when separate and when linked measured to 0v while -5dB GR is on each channel. Make sure the switch and threshold settings on both comps are the same. Ok, So just and FYI that I w...

Yes trimpot spot is correct across makeup pot. This is very seperate from the link area of the circuit. Did the link switch work before? Do you have a photo of the link pcb? Yes the link switch used to work just fine only a slight difference between the two -5db readings on the meters when engaged....

Ok never seen this before and the trimmer if done correctly will not affect this. Check the mac link pcb has the 10 pin headers and cables the correct way around and no shorts to 0v. With link switched on unplug one ribbon cable from the link pcb at a time to see if both comps come back to -5dB wit...

Ok, I just got done adding the trimmer pot to balance the two output pots. It wound up being 98.6K and I got the outputs VAC to be equal now when you switch on the VU meter. Thanks so much. I have done the calibration again and made some slight tweaks to adjustments trimmers but now have something ...

Hi folks, got a question about the 111dc circuit boards, do any of the resisters need to be fitted? I built a BA4 with jlm 14 inputs 99v opamps and 111dc output transformers. with the 48v 25 watt power supply. They are all working but I'm getting a pulsing from the power supply. The leds get dimmer...

Hi Joe, I've just built my LA500A. Great build, great design but sadly I have a couple of issues. What's working? Both coloured LED's, meter LED, makeup gain, hardwire bypass. No smoke What's not working? Don't appear/ hear to be getting any gain reduction. no movement on the meter regardless of sw...

Hi Joe. This circuit JLM99 works in a +/-16v? I sent you a email about Go Between Plus. Thanks, Luís The JLM99*MB pcb runs the JLM99v on whatever power rails you send in which used to be +/-24vdc and then makes +/-15v rails for the dc servo ic. You could just run in +/-16v power in and link over th...

Alex1990 wrote: ↑

Wed Feb 07, 2024 7:11 pm

Actually - I am getting 2 x 20k measurements on the front lugs so maybe pot is fine after all? But can’t understand where issue would be on PCB. Perhaps it’s easier and quicker to get a new pot PCB at this point.

OK email me so we can workout the pot kit or parts you need

saxmonster wrote: ↑

Wed Feb 07, 2024 3:44 pm

Thanks Joe,
Once I get them equal should I drop the output of my daw so that I get 1.23vac on both opto outputs so I can zero out the meter when I recalibrate?

Yes