JLM AUDIO

billface wrote: ↑

Tue Apr 16, 2024 4:46 pm

So just to be clear, are you saying this arrangement will work?

Attach photos to your post. I cannot get to Google photos

Probably the first in a series of stupid question from myself. 1) Do the J99 sockets get soldered into the board? I said on the instructions not to press them in and to use a piece of cardboard to hold them in, but now the J99 is inplace it seems a bit odd that is a bit loose. 2) I put the DIP8 soc...

Success!! Or so it appears. I've completed the meter calibration process, and everything worked as expected now. I will take it to the studio now to put it in my main rack for an audio test. Joe, for others reading this I'd like to run a theory by you. I tend to solder from the underside of the PCB...

I was trying to put the opto back in, when I noticed the anode joint doesn't look good. It appears that the pad is gone. Perhaps it was already a bit loose earlier: IMG_4209.jpeg In the instructions you mention that SCv3 has extra/alternative holes for U1 and U2. I have SCv5. Are those the holes I ...

ddld wrote: ↑

Wed Apr 03, 2024 5:23 pm

Haha, ok Well, one possible cause is eliminated then. I’ll put the opto back in.

How do I proceed now? My original problem is still there.

Let me know if the comp still does not show GR reduction but can be sent to 0 on the VU meter with the zero trimpot?

I've hooked the opto up to two multimeters, and the results are... Meas2.jpeg Meas1.jpeg The Fluke is measuring resistance on the bottom leads, the Brymen is in diode test mode. Notice that the red probe is connected to the left top pin, while the dot is next to the right top pin. This means that t...

Ok, I think I found something. I’m spelling this out to avoid dummy mistakes. If I put the red lead of the DMM on the pin marked with the dot, and the black lead on the pin immediately next to it, I get an open-loop reading in diode test mode. If I switch the leads (black on dot, red on the pin nex...

Hi Joe, Thanks for the quick response. I believe the U2 opto was oriented correctly, but since I wasn't 100% sure if I was seeing the dot or a smudge on the package, I popped it out with the desoldering gun. Here is what it looked like when U2 was still in: IMG_4148.jpeg Here's a top level view of ...

Hi Joe, I finished the LA500a, my first JLM build, and I really like the component layout, structure, and quality of the kit. The modular approach is really nice. The meter calibration process is giving me a bit of trouble, so I think I have a problem somewhere that I hope you can help me diagnose....

Heya Joe, Not sure if my post got confused with another partially, but I've got it sorted out now :) I had a bad solder joint that 8) was causing some trouble on the Control card. Just want to say I'm STOKED on the way these are sounding. Thank you for responding promptly. I am grateful! Much appre...

Hi again Joe, Now that I've got my pair of GEQs all set up, one of them is working great but the other is having some prominent static when I engage the faders toward +. Thanks Ok, I would have never removed the socket no matter how melted as long as the metal sockets were not touching. Your bottom...

I have worked on this mod with the GAP Pre 73 MK3 only with the output JLM111DC transformer. At the input I have the carnhill vtb9045m. For a very long time I used 1.5v at the primaries, but after a while I found the sound was a bit muffled, comparing it to IC preamps. So I looked for alternative v...

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 lo...

Hey there, Completed my build on the GEQ500 and did my first test run with my R9 and R10 carbon resistors popping (10 R). Any recommendations on things I should check to diagnose? Turns on briefly and then they pop. Thanks Hi If they burnt while you were doing the jumper test on the Edge pcb by its...

Notes and Errata 1. Kits all have extra caps to change neck to bridge HPF to wider as suggested by some of our early users. See below new cap values to fit. 2. We have had some Black front panels the jack hole is tight. It is ok to file or drill the hole to correct roundness and size. 3. Make sure ...