Betapack 2 DMX problem

[mrg198]

Hi,

 

I have a couple of BetaPack 2 (Mk II I think)s that both have a DMX problem. Basically, they work fine at the end of a chain, but if I try and connect the DMX output to something else (most often the other pack) the downsteam devices misbehave or fail to receive data entirely. The downstream dimmers flicker the outputs or just go up and down at random, or don't work at all. Inside, it looks like the sockets are just wired across. Should there be some sort of isolator in there? I'd like to get them fixed as the DMX chain can be quite long if I have to go to everything else first and then back to the Betapacks and if I want to use both, I have to use a desk with 2 universes (or a splitter which I don't have). I have tried plugging in a DMX terminator I found at the end of the chain but it makes no difference.

 

Suggestions?

[peternewman]

Have you checked the Betapack's aren't terminated? IIRC they have a switch behind the panel, near the address wheels, where you can set them to terminate.

[indyld]

As you report the same problem with both dimmers ( I assume you have tried them both seperately) then termination switch might be the problem. It's ages since I used one, but I only remember the "DMX fade/hold" switch on the front panel.

 

I have had problems in the past with these dimmers DMX out bus. I remember coming up against some racks that had to placed at the end of the chain, even though they worked fine for DMX in, because they did not pass signal through.

 

Afraid, I don't know exactly what the fault was ( you know how it is - problem overcome, gig finished, mark it up and send it back).

 

Best of luck.

[Wuddy]

I had a similar problem on some Strand dimmers, it turned out that the DMX cable had been trapped/kinked at some time and the cores within the cable were damaged, it worked ok with any one dimmer but when others were linked in it just went random.

 

Only found it out when I used a Strand MX desk and as it booted up and did the self test it came up "output short or IC2 fault" or some similar error message.

[Neil Hampson]

I'm pretty sure the Betapack II's don't have a termination switch on them, have you been able to isolate the fault to one unit, or do both act in the same way? The DMX in and Through will be wired stright through pin to pin, there should't be any devices between them (This is after all just RS485 - Multidrop) Check the continuity between the plug and socket of each pack and of course test the cable...

The packs themselves are not capable of transmitting a signal onto the DMX line unless there is a serious fault somewhere.

If you swap the packs over I.e plug pack two into the chain first, does the other pack behave normally, or erratically? (this will help isolate the problem) I would really suspect a bad cable, or if the pack is at fault maybee the joints between the DMX in and out.

[mrg198]

Apologies folks, I've just realised that I think they are Betapack 1 units not 2. I've had it in my head that they were 2s but looking at the zero88 website photos, they look like the 1s not the2s. (I'm not with the units atm to check physically). If I have a simple chain with the two units and it begins to play up, I can try swapping the order over, but get the same result. Sometimes they work fine for a few minutes and then just start randomly changing levels. I have tried using brand new VDC made cables and other people have experienced the same problem when they've borrowed them. Both units act the same. I don't recall an isolator switch, but I'll look when I'm next with them (I'm on holiday currently).

 

When I've had them apart before I recall they were simply wired straight across. I did have trouble in the past with a dodgy connection, but I resoldered it and I thought the problem was solved. Until recently, I tended to only use one at a time so I didn't realise they were still playing up plus I was using them with a Zero88 Lightmaster XL desk and had various problems which I didn't know if they were dimmer or desk related. I now know that the desk has it's own problems with not providing a stable DMX output - I plugged it into my Hippotizer and the output levels jitter all over the place - not ideal for selecting media based on specific DMX values!

 

Just to clarify - I'm not using them with the XL desk any more. I'm using a Chamsys MagicQ MaxiWing or Lightfactor Zip 12 desk and other are using a Pearl 2K4 or ETC Express with them so I don't think it's desk related

 

Edited to clarify and then to cure fat mouse finger syndrome. Apologies if you saw the mess of nested quotes I posted for a few minutes!

[mrg198]

Update:

 

I've dismantled the pack and discovered what I think is the problem. The DMX output socket has a small circuit board with a few resistors on it soldered to the pins. The circuit board is positioned in line and against one of the captive nuts for the rack ears such that the bolt holding the rack ear on is across the back of the circuit board shorting the blobs of solder - what a crazy design! Turning the socket upside down means the board is facing the other way away from the bolt and appears to solve the problem.

 

Thanks for all your help.

[ianknight]

Hmmm - except from memory - in the Beta 1 DMX the sockets (as the units came out of the factory) didnt have a PCB fitted but used wires soldered directly to them to obviate this very problem.

 

It is more probable that someone salvaged the socket PCB from something else and thought it would be neat to use without realising what might happen. Many Beta 1's were analogue only when they were built - the DMX card was for a long time an optional accessory (and also quite a handy freestanding 6 channel demux!) - so it is very likely that someone added DMX later.

 

Of course, Keith will now pop up and tell me I'm wrong! :D -

[mrg198]

Hmmm - except from memory - in the Beta 1 DMX the sockets (as the units came out of the factory) didnt have a PCB fitted but used wires soldered directly to them to obviate this very problem.

 

It is more probable that someone salvaged the socket PCB from something else and thought it would be neat to use without realising what might happen. Many Beta 1's were analogue only when they were built - the DMX card was for a long time an optional accessory (and also quite a handy freestanding 6 channel demux!) - so it is very likely that someone added DMX later.

 

Of course, Keith will now pop up and tell me I'm wrong! :) -

 

Interesting. Sadly despite what I said earlier, we still seem to have trouble with one of the packs. As far as I can tell it's not shorting, it just doesn't pass through DMX occasionally. Grrr.

[Graham NZ]

We can fault find this with you on the phone. 01633 838 088. As many people on here will attest Keith is really helpful. It normally means a solution instantly rather than having to try various options and report back. if it is outside normal hours we can help with this if you let us know.

 

Best

Graham