Anyone familiar with this ETC L86 behavior?

LesWilson

Well-Known Member
My 96 dimmer L86 rack is circa 1990. It's been in my venue for 10 years. Except for SSR failures, it's worked reliably until last year. I performed a Cap repair on the opto-isolator module. I also had the following problem:

Independent of the opto-isolator failure (I think), the center bank of dimmers failed to work properly and its EM64 module Under Voltage light was solid, Over Voltage was flashing, Backup was solid and Data was solid. According to the manual, this means there was under voltage condition, problem with EPROM and "System is receiving DMX 512 data (normal). The manual does not list ON as a possible condition for the Backup light.

I swapped the module with another bank and the problem moved to the other bank. Putting in a spare (from its original installation) resolved the problem at the time although some of the modules showed all 4 lights lit solid. After 6 months, the failure occured again. Swapping in my last "working" spare resolved the issue.

After about 4 months, the failure reappeared just before the start of an event. In desperation, I swapped in one of the units that had failed previously. It worked. But after a month the failure returned. Swapping in previously failed modules did not resolve the problem. ETC Tech support said a repair was needed. It's $600.

Here's the thing, after getting approval to purchase a used EM64D off eBay and about 4 hours of disuse, all modules showed normal and all banks worked fine; For now.

Three Questions:
Has anyone experienced this?
Screen Shot 2020-03-28 at 7.23.26 AM.jpg
Any ideas as to what's going on?
Is the EM64D compatible with the EM64 modules in the other banks?
 
Thanks. I did call ETC Support. They said the EM64 should be sent in for repair ($600). We can't afford that so we bought a used module for $200. My concern is the possibility that something else is causing the failure. Florida Power and Light is not beyond suspicion.
 
Understand. It's a lot to expect electronic equipment to keep working after 30 years especially without a major overhaul. Quite a testament to the LMI design that it has worked this long. Almost as amazing as the ubiquitous TTI MDS 6-packs from 70's that seem to keep on ticking.
 
Thanks. I did call ETC Support. They said the EM64 should be sent in for repair ($600). We can't afford that so we bought a used module for $200. My concern is the possibility that something else is causing the failure. Florida Power and Light is not beyond suspicion.
@LesWilson Sight unseen and clutching at straws from afar; you're dealing with a pluggable module: Power down, thoroughly clean / burnish male and female contacts, as well as any pluggable jumpers possibly (I've NEVER seen one) on the card; re-power and PRAY!
Toodleoo!
Ron Hebbard
 
Hmm, in my experience the EM64 modules are pretty reliable so having multiple failures sounds unusual. There was a time, however, when I did have to send in one for repair. A neutral connection inside the rack had gone bad. This condition damaged a transformer on the module. I believe at the time I was also seeing voltage errors.

I do not know if something similar is happening in your case. I do not see anything out of the ordinary in the picture. Often, a damaged transformer will look discolored. Any inspection of connections inside the rack should be done by someone who is qualified.
 
It's very hard to tell from the angle, but does C4 maybe look a little bit questionable? More generally, the symptoms described sound to me like they could be due to a noisy/poor power supply, and C4 (along with the other electrolytic capacitors in the area) are clearly part of the power supply, and their failing could easily lead to ripple and other gremlins that cause improper operation.

Reseating all the socketed chips in their sockets wouldn't be a terrible thing to try, either.

(Looks like it's controlled by a 6809 processor; I always thought they had a particularly nice instruction set for an eight-bit processor, though I haven't had reason to program one in assembly language as yet.)
 
It doesn't look obviously bad to me from that angle. The top doesn't seem to be bulging out. That doesn't mean they're positively good, of course, but no more suspect than a fair few other things.
 
It doesn't look obviously bad to me from that angle. The top doesn't seem to be bulging out. That doesn't mean they're positively good, of course, but no more suspect than a fair few other things.
So with several of these to work with, I am willing to try doing some work like reseating the ICs and cleaning contacts. Which caps would you suggest I replace?
 
Without other options, I would do the following. Clean the card connectors with DeoxIT D5, as well as the mates in the rack. Replace all of the electrolytic capacitors, because visual signs are seldom accurate. I'd be willing to bet money that C2 is baked from heat from T3. Observe static discharge prevention while working on it (no fleece). I would also add some solder and reflow the legs of T1 and T2. Be sure to unfasten the three regulators from the chassis before further disassembly.
 
@RonHebbard I can't get into the venue given current public health restrictions but I'll try cleaning the CB contacts.

I could only find a used EM64D. Are the EM64D modules interchangeable with EM64?
Sorry @LesWilson ; I've never owned one, let alone seen one, I've ZERO knowledge if they're interchangeable or not. My apologies if I've mislead you.
Toodleoo!
Ron Hebbard
 
@FMEng We're not going to be in a financial position to do the $600 ETC repair for a long time. Thanks for the clear concise procedure. Our site TD green lighted doing it on one of our spares. Nothing to lose. It only took an hour to dissemble and reseat the ICs. I hit the sockets with Deoxit D5 for good measure. Mouser had the Caps and is shipping today. $23 total. No obvious cold solder joints but will reflow T1 and T2 for grins. Will let you know. Thanks again.

EDIT: These are the Caps needed
Mouser #:80-ESW226M010AC3AA
Mfr. #:ESW226M010AC3AA
Desc.:Aluminum Electrolytic Capacitors - Radial Leaded Aluminum Electrolytic Capacitors - Radial Leaded 10V 22uF 105C 3k Hour Radial
$0.23 ea
Quantity 3​
-​

Mouser #:594-2222-120-16222
Mfr. #:MAL212016222E3
Desc.:Aluminum Electrolytic Capacitors - Axial Leaded Aluminum Electrolytic Capacitors - Axial Leaded 2200uF 25V 20% Axial
$5.98 ea
Quantity 2​
-​

Mouser #:871-B41851F7227M000
Mfr. #:B41851F7227M000
Desc.:Aluminum Electrolytic Capacitors - Radial Leaded Aluminum Electrolytic Capacitors - Radial Leaded 35VDC 220uF 20% STD Leads
$.43 ea - Quantity 2
 
Last edited:
UPDATE: Replacing the 7 capacitors was straight forward with the right soldering tools. When I ordered the replacements from Mouser, I could not find 2200uF caps as the originals. What I ordered was fatter and shorter. I didn't think it mattered until final reassembly of the tray. The tightening bolt only has a few millimeters clearance. Oh well.

Testing will have to wait until we're past this lockdown.
 

Attachments

  • IMG_5760.JPG
    IMG_5760.JPG
    638.3 KB · Views: 134
EPILOG: I was able to install and test the "refurbished" module. However it did not resolve the problem. The data light did not blink but over and under voltage lights were solid. The bank of dimmers did not work. One bit of good news is that it didn't let any smoke out. The eBay EM64D module worked a treat however.

I'm open to other ideas. TIA
 
Upper right IC chip looks possibly discolored in the top right corner. Sometimes a sign of trouble. If you put your nose up to it you may be able to tell if it's lost some of its magic smoke.

Also the G5 chip middle right looks cockeyed. Could try reseating it.

Wouldn't say either of those are likely but since you've got a working unit and this one is basically a science experiment, worth playing around with it a little.
 

Users who are viewing this thread

Back