Control/Dimming - LMI L86 Dimmer Rack Question

[FireInTheSky]

So, I'm in the process of repairing an LMI86 48-rack, and I discovered something interesting. With cams hooked up, but no console connected and the control cards reset (so no DMX artifacts from previous use), metering the soco outs hot to neutral shows ~89VAC. This seems to have no effect on the actual output though. When I hook up some par bars, there's no ghosting, and all of the circuits fade up to full and down to 0 normally. Here are the combinations I tried and their readings:

	Console Hooked Up?	Data/Passthru Cards In?	~VAC
Direct StagePin Out	N	N	88
"	N	Y	88
"	Y	N	88
"	Y	Y	88
(Dim@100 on Console)	Y	Y	116
Soco Out	N	N	90
"	N	Y	90
"	Y	N	90
"	Y	Y	90
(Dim@100 on Console)	Y	Y	115
(Unpatched from bay)	-	-	0

Is that normal and I just never noticed it before? Is there a problem with the rack?

[JD]

Yes, this is normal.

Without a load, you are reading the leakage through the firing circuit. You should have a minimum of a 50 watt incandescent load attached to get any reliable readings.

[derekleffew]

Without a load, you are reading the leakage through the firing circuit. You should have a minimum of a 50 watt incandescent load attached to get any reliable readings.

It might be noted that one experiences this phenomenon with any Dimmer, Thyristor / Dimmer, Phase Control , not just those from LMI using an SSR.

[STEVETERRY]

Yes, this is normal.

Without a load, you are reading the leakage through the firing circuit. You should have a minimum of a 50 watt incandescent load attached to get any reliable readings.

What Derek and JD said.

ST

[FireInTheSky]

Thanks for the responses for that question.

Now, a separate question:

I'm wiring up a new back panel for an LMI86 12-pack dimmer. The only thing I'm not sure about is wiring up the Control Terminal Strips. I wasn't there when this dimmer was taken apart previously, so I didn't see that particular part of the disassembly. The wires are already run from the Terminal Strips to the Control Card plug, so I think I just have to run wiring from the DMX connector to the terminal strips, but is that it? Do I need to run any jumpers between any of the individual terminals? Or should it just be 3 wires for Data +/- and Com?

[DavidNorth]

If this is a portable pack with cams, then the data connection is through the front of the EM-24 control module.

If this is a wall mount installation pack, the the data connections to the terminal strips are in this document http://www.etcconnect.com/docs/docs_...ls/L86WLPK.pdf.

Let me know if you have any questions,

David

[FireInTheSky]

I actually have that document. And everything from the terminal strips to the control card is already in. As far as I can tell, the only wiring I need to do (1220 WP) is from the DMX connector to J12#15, J12#16, and J11#13/14. I just wanted to make sure that was it. No jumpers between, say, J12#1 & 8, J12#2 & 9, etc...

[DavidNorth]

The Take and Take Return connections would be for architectural wall stations. If you have [the very rare] wall stations, you would also land their control output to the Control terminal strip locations. The programming for Control input numbers to dimmer numbers is kept in a serial EEROM and done at ETC, but I'm not sure we can do it anymore.

I am assuming you do not have wall stations.

Let me know,

David