Search found 9 matches

by greenote
Fri Aug 12, 2016 5:59 am
Forum: JLM Audio Kits
Topic: LA500 opto comp leveling amp BUILD THREAD 500/51X
Replies: 221
Views: 218663

Re: LA500 opto comp leveling amp BUILD THREAD 500/51X

Optos appear to be in correctly. Lettering appears as in the build guide. I checked the 10R's as I had blown those on another build. R14 replaced with 1.8k.

IMG_5298.JPG
by greenote
Wed Aug 10, 2016 3:51 pm
Forum: JLM Audio Kits
Topic: LA500 opto comp leveling amp BUILD THREAD 500/51X
Replies: 221
Views: 218663

Re: LA500 opto comp leveling amp BUILD THREAD 500/51X

Greetings, I have completed the build and performed the calibration on VU and GR, however the threshold doesn't seem to function. The unit is passing audio and the Make up gain is working.

I checked continuity from threshold pot wires and PCB.
Any suggestions?

thanks
Todd
by greenote
Wed Aug 10, 2016 2:37 am
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Thanks Joe. GR meter still isn't right, but easy enough to use my ears and the VU meter. I've got two older LA 500s, one has a meter issue and one doesn't pass audio. I'm glad I got a handle on this one as it should make troubleshooting the others easier. I love the smooth sound of these guys and th...
by greenote
Tue Aug 09, 2016 4:45 pm
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Okay replaced the 2 10 Ohm resistors. VU calibrated, GR now on zero, no motion on trimmer. It's working great and the VU gives me relative compression indicator. Beefy
by greenote
Tue Aug 09, 2016 2:08 pm
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

I believe this op amp was initially plugged in backwards. You're referencing R23 and R24 back on the Edge Board. I saw these darkened, but they still measure 10 Ohms. I'll rip them out and report back. I did get voltages on the LA500SC PCB opamp. Perhaps it's moot, until I replace the 10 Ohm-ers 1. ...
by greenote
Tue Aug 09, 2016 8:53 am
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Okay, sorry I refer that was as the Mac.
Had to de-solder the meter to remove PCB and get shots of the board.
I've attached photos and will send the voltages from the op amp on the LA500SC PCB after re-assemby.
IMG_5285.JPG

IMG_5286.JPG
by greenote
Sat Aug 06, 2016 2:55 pm
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

I'getting the following voltages

Edge Connector
12. +15.4 volts
14 -15.7 v

Chip
1. 0
2. 0
3. 0
4. -14.9 volts
5. 0
6. 0
7. 0
8. +14.6 volts

JLM 99v
-14.9 v
+14.6v

Todd
by greenote
Sat Aug 06, 2016 10:16 am
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

Thanks Joe, If the meter pins without audio in you have a solder short usually between two solder pads on the LA500SC or another fault on that PCB. Don't see any shorts, photo's attached. Perhaps I should check the value on the blue film caps as I saw there minor shipping error in previous post. Wit...
by greenote
Thu Aug 04, 2016 10:01 am
Forum: JLM Audio Kits
Topic: LA500A opto comp leveling amp BUILD THREAD 500/51X
Replies: 151
Views: 107764

Re: LA500A opto comp leveling amp BUILD THREAD 500/51X

I just completed the new version. It passes audio and compresses. The threshold/makeup pots work as does the meter. However I cannot get either VU or GR trimmers to budge the needle. The needle is pinned to the Right (RED). I've read and re-read this thread and the old one thread. I've re-heated the...

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