Dimming Console Not Powering Up.....

[partyanimallighting]

Hi Wizards,

I encountered an issue with my Elation Scene Setter dimming console a couple months ago and I've finally gotten some time to put up a post to get some advice (actually because I have a spare console so I just stuffed the problematic console in a corner). This problematic dimming console is on a slide out drawer under my work desk and I use it only for testing units so it's not abused in any way. Anyways, I was testing an LED PAR a while back and I detected the lovely smell of burnt components coming from the console. It then died completely, no power, no LED's, no display, so then and there I opened it up to find the source of the smell. It so happened that the 8 pin SN75176 on the power board was completely fried so I figured that was the only issue, removed the bad IC, put in an IC socket (for future burnouts), put in a new transceiver and powered up and..........nothing. I did some testing tonight (finally decided to take a stab at it) and voltages at the ribbon cable feeding the control board from the power board seem to be fine. I'm getting 12VDC at the "POWER IN" and 5VDC at the "+5V" terminals and the readings are the same on the LM7805 so it seems the blowout damaged a component on the control board. I did some further probing at the ribbon terminal input on the control board and diodes D107 and D108 appear to be fine, also I'm getting 5V on each leg of Q14 and I also checked voltages at the backup battery (3.3V). I'm kind of stumped from there as I'm thinking maybe 74HC573D below the terminal may be faulty? Or maybe the 40 pin microcontroller on the flip side? I'd really appreciate some help to get this test unit up and running as I don't want to waste the slide out drawer that I installed to hold this unit as the other unit I'm using for testing does not fit! 😁

 

[timsabre]

If the micro has +5V to it, then the most likely thing is the micro has been zapped by whatever fault took out the 75176 (sounds like high voltage on the DMX line).

I recommend you invest in an optoisolated DMX splitter to protect against this sort of thing....

[partyanimallighting]

Hi timsabre, is Q14 the "micro" you are referring to? Is it that this particular component is on the 12V leg and should be reading 12VDC and not 5VDC? Or is the "micro" you are referring to (datasheet just downloaded) the H11 L1 optoisolator adjacent to the SN75176? I ran a diode check on the H11 L1 just in case (powered up) and I'm getting readings in both directions on pins 1 and 2 and as far as I know, that's not consistent with a proper diode reading. I also checked voltages from pin 5 to pins 4 and 6 and got 5V at pin 6, which seems correct, but only 0.3V at pin 4. If you are actually referring to H11 L1 as the possible problem component, why would I get correct voltage readings of 12V and 5V at the ribbon terminal input on the control board?

As for using an optoisolated DMX splitter, I do use them with each and every console when I'm out on jobs or installations but in this case, it'll be just another piece of equipment on the work desk taking up valuable space so........

In reference to the "micro", I always state here in each of my posts in this forum that I am in no way familiar with all the terms and jargon but I follow instructions and advice well hence my attempts to repair my defunct units and I have received so much help from you guys and because of this help, I have resuscitated so many of my units and I am indeed very grateful.

[timsabre]

I mean the 40 pin microcontroller - I can't see the part number

[sunray]

1 hour ago, timsabre said:

I mean the 40 pin microcontroller - I can't see the part number

No the chips are always ground off to prevent cloning.

 

There are a pair on Ebay in significant state of dilapidation which could likely provide appropriate spares. 

[timsabre]

No I meant I could not see the board ident number on the photos. It'll be an 80C52 or similar, these controllers are all modifications of a scanner controller I designed for Abstract in the late 1990s.

[partyanimallighting]

Hi all, following all these helpful posts, I peeled the labels off the "micro" and the MCU below and the microcontroller number is AT89C55WD. I downloaded the appropriate datasheet and, based on what you guys' advise above, I'm assuming that if I'm getting 5VDC across Pin 20 (gnd) and pin 40 (vcc), that means voltages coming into the main control board are fine and this "micro" is fried but please warn me if on the wrong track here. Checking back, I'm seeing that I actually picked this unit up on eBay last year August for $30.00 but I am a little disappointed that I didn't get a year's service out of it......sigh.......

[partyanimallighting]

I did find this in the ADJ Parts Store for $22.00 but it's out of stock and my guess is, it'll probably be out of stock......forever.

 

https://parts.adj.com/catalog/product/view/id/18147/?parent_id=20307

[timsabre]

The microcontroller has its software internally on Flash, you'd need to get the right chip to match your unit. The ADJ one may or may not be the same...

[alistermorton]

Looks like it has the same number, other than an A rather than B revision. Ray's suggestion of a donor machine may be the only solution, but without probing with a 'scope, voltages only tell us part of the story.

[sunray]

51 minutes ago, timsabre said:

The microcontroller has its software internally on Flash, you'd need to get the right chip to match your unit. The ADJ one may or may not be the same...

Indeed. I recently worked on a Cobra Colourcontrol24 (2 banks of 12 faders) which seems to be identical to my Chauvet Stagedesigner50 (even the part number and batch number of PCB were the same) and my faultfinding consisted of swapping chips between the 2 desks. However there are differences in functionality, only by different programs in the micro's

[partyanimallighting]

Actually timsabre, the ADJ and Elation are identical internally, the only difference is the screen-printed brand name on the unit. Same company, same controller. But it being out of stock, availability may be never. Anyway, I'm planning to reassemble the console, give it a got wrapping of bubble wrap and toss it in storage until maybe I come across a junked one for cannibalization but is there any way I can ascertain for sure that it's indeed the "micro" that's shot? If I'm getting 5VDC between pin 20 and pin 40 on the micro and no power up, it that it? Time for bubble wrap? I had the same problem in the past with an Elation Magic 260. Same issue, bad microprocessor.

[timsabre]

It almost certainly is the microcontroller if there's power but it's not doing anything. If you have an oscilloscope you could check the crystal oscillator on pins 18-19, I have known these fail due to bad crystal. But as it started with a dnx meltdown it's likely that fried the microcontroller too. 

[partyanimallighting]

Well, I opened up the unit just one more time to double-check. I re-seated the micro-controller (last chance) and powered up. The readings remained the same, 12V and 5V power in from the ribbon cable to the control board and 5V between pins 10 and 20 at the micro so I've read the unit last rites (until I can source the micro) and bubble wrapped it up toss in storage.

 

Thanks for all the help and guidance guys!