analogue LD 2400 repair

[goatiemon]

good day l have 2 leprechaun LD 2400 6 channel dimmer packs
(analogue jones pin control)

l used them for the first time the other day
and channel 6 on one of the packs wouldn't respond to control

it isnt a control signal problem (like it usually is with jones pin)
l tried various channels etc

then durring a show

l lost channels 5 and 6 on the other pack....

all dead chanels light if you push the red (@100%?) button

l havent done any trouble shooting yet
l know leprechaun has good schematics and such available

but was hoping some of the knowledgeable folk on here could point me in the right direction
common failures or the right sort of thing to check

thanks
goat

 

[cbrandt]

The last time I repaired one of these things, I and the techs at Leprecon were certain that the problem was the main control card, having had similar problems before. Turned out to be the individual dimmer card. Not sure where to point you, if you're trying to repair the boards yourself, but Leprecon still builds those old boards for repairs, and for a decent price. I'd give them or your Leprecon dealer a call to see what they can get them for.

Best bet to trouble shoot is to move the dimmer cards around, and see if the problem stays on the channel, or follows the cards. Remember to power down and remove from power before poking around inside, it is really tight insider there to move those cards around.

 

[FatherMurphy]

First thing to check is if you have a soft patch problem at the console, or if you might have control cable problem - a broken wire or a dirty blade on a connector will create the problem you're seeing. If you have two packs, swap the control cables and see if the problem follows.

If you're not familiar with poking around inside electrical equipment, call Leprecon at (888) 422-3537 or your local dealer at this point.

If you are comfortable opening cases, and the problem is with the individual dimmer, LD-2400's have two trigger cards (also called ramp cards), one runs channels 1-3, the other runs 4-6. The ribbon cables that run across the top front of the unit carry signal from the ribbons to the individual power modules. You can test the trigger card by simply swapping ribbon cables from a working channel (within the 1-3 and 4-6 ranges) to the non-working channel, and seeing if the formerly non-working channel now responds to the good channel's control (this is MUCH easier than moving entire cards just for a test). If the problem moved, you have a bad trigger card. If the problem stays put, you have a bad power module. Both are still available from Leprecon.

Since you get results from the test button, I'm assuming that some of the other common problems aren't happening, since they would result in no light at all.

Manuals can be found here.

I've had my screwdrivers in more of these than I can count, let me know if you need additional help.

 

[goatiemon]

thanks FatherMurphy

exactly the sort of hints l was hoping for
l am comfortable opening them up
with alittle (alot) help from this forum
l repaired several analogue scrimmer packs a while back

already tried to see if it was a control issue
it isn't --
l don't have the right control cable break outs so l popped the pins and clips (female ends)
out of their bakelite plugs; and spaghetti patched them individually
giving ample opportunity for testign with known good control channels

l dont have a board a the moment to test with
but when l get one of mine in the same room as these dimmers

l'll do some swapping and try to see which cards are bad

thanks again
goat

 

[FatherMurphy]

The control connectors are usually 8-pin Cinch-Jones connectors, square black plastic things with flat blades, four horizontal, and four vertical. Pinout is pins one through six are channels one through six, seven not connected, and eight common. Later they had a locking ribbon cable as an option for touring racks, CJ wasn't always reliable about staying fully seated on the road, and dirty pins is a common problem with CJ.

LD-2400 are 0-10 vdc analog, 0 being full off, and 10 being full on. They can be tweaked some to adjust to slightly different upper and lower values.

I don't think I've ever yet see control die on a power module, resulting in test button working, but not control. Usually an SCR locks on or off, or the PowerLock connector melts to the point that the contacts separate, leaving the card with no power (or the lighted circuit breaker goes weak, again leaving you with no power on the that module). The card has to be getting low voltage power from the trigger card for test to work, so chances are against the ribbon cable simply being loose.

Often the trigger cards can be repaired by changing one or more of the LM324 IC chips, either by cannibalizing a known good card, or by picking up a few from a local electronics store (or online vendor). I've also seen cards that died because someone missed the potentiometer at the bottom of the front of the card when inserting a screwdriver to adjust trim, and pried the pot off the circuit board, plus I've got some that I just don't know how they died (I lose interest in component-level repair when I have to start unsoldering things, and an hour or two of my time vs. the cost of a new card is a pretty close balancing point).

 

[goatiemon]

thanks ya'll

l finally got to poking around in my dimmers

and it turns out my OP was a little wrong

l have 2 packs lets call them A and B

unit A the "full on" buttons work but the channels 3 and 6 dont respond to control
(the led status lights do act properly)

l swaped the conenctors around and it appears that the problem(s) are with both of the trigger cards
the individual dimmer cards are ok

so l figure l'll look into sourcing a couple LM324 IC chips


unit B

channel 5 is stuck on @100

5 and 6 dont respond to control
(and the leds on 6 dont light up properly)

the #5 dimmer card (power module?) is bad probably the scr?

and the 4-6 trigger card is also bad
so l'll try the LM324 IC chips as well

semes strange that 3 out of 4 cards failed on #3 (6)

any other thoughts?

thanks
alot

goat