Zero88 Demux dead.

[Light Console]

Hi all, am quite ticked off today, looks like I lost a desk and a demux to the same fault! (see more in another topic...)

 

To bring you up to speed - I have a 1990 Zero88 Demux, ex hire of Stage Electrics, used all day every day at the Gantry for a couple of years then I got it for nowt when they closed 5 years ago. As a result of Stage Electrics, it has the negative output kit, and is wired to 37 pin soca, which is handy.

 

I have only had a few gigs a year with it, and without fail it has worked well. It was on all day for a day in July when my venue became a TV studio.

 

This week, when I turned the Demux on, it would start flashing through the LEDs as normal, then all LEDs (without the 7 segment displays) would light up dimly.

 

On popping the lid off, it was quickly apparent that the battery had died and leaked (not that I would have thought there was one in there!). All tracks seem to buzz out OK. After a call to Zero88, it was quickly confirmed that it was probably the dead battery causing the fault conditions. It is a Varta Mempac 3.6v 100mAh blue battery. This is quite hard to find out about on the internet, but one site said (might have been CPC) that the new NiMH (Turquoise) 3.6v 150mAh battery will work as a direct replacement. After soldering in the new battery, the same fault conditions were exhibited.

 

Thanks for reading this far, here are the questions - Is it true that the NiMH battery replaces the unknown flavour of the blue battery directly? Does anybody know where to get a blue battery from? Is it worth spending too much time on? (I don't do my own gigs now, but it would be handy to get a system going for floor dips and extra rig circuits.

Thanks again.

[boswell]

Leave it powered up for a few hrs to get some charge into the battery, (they are supplied almost dead)

Then try it again

[goochr96]

Have a word with Ian Knight, at CTS (Central Theatre Supplies) He is on here too. He fixed our Demux earlier in the year, that was a dead battery.

 

Ian - Hire & Service ian@centraltheatresupplies.co.uk

Telephone +44(0) 121 778 6400

[Light Console]

Thanks chaps, I had thought about (and now will) leaving it on for a while, but was unsure about damaging anything else. I guess it is dead enough already! Will try and contact Ian tomorrow, but we have a full day get-in tomorrow.

 

 

Update at 20:08 - all seems to be working again. Yipee! Sadly the same can't be said for the MX, never mind!

[boatman]

Thanks chaps, I had thought about (and now will) leaving it on for a while, but was unsure about damaging anything else. I guess it is dead enough already! Will try and contact Ian tomorrow, but we have a full day get-in tomorrow.

 

 

Update at 20:08 - all seems to be working again. Yipee! Sadly the same can't be said for the MX, never mind!

 

New NiMH batteries should be charged for a minimum of 14 hours before first use. Since you have replaced a 100mAhr with a 150mAhr it's probably worth making that charge time 21 hours. Although NiMH batteries don't suffer the same "memory effect" as NiCd they do benefit from and occasional full discharge/charge cycle.

 

HTH

 

John

[DavidLee]

Although NiMH batteries don't suffer the same "memory effect" as NiCd they do benefit from and occasional full discharge/charge cycle.

NiMH cells do have a very much higher self-discharge rate, which may be significant if your demux were only used sporadically.

 

David

[Light Console]

I have tagged this onto the end of the old topic, as I am the OP, but the question is going to change.

 

I never did get to contact Ian, as the Demux has worked without fault since my last post. It was used less than three weeks ago, and would have been on for long periods of time. But today, it was back to the old tricks.

 

It will flash the leds, then try to chase the 7 segment display, but gives up, and all leds stay on dimly.

 

It is time to move on, but to what? I have 2 x Betapack 1, 1 x Alphapack 1 and 2 x Minipak 1, all in all 21 channels of dimming. A zero 88 Demux 24 would have been first choice, but at £350 odd, too much, as I don't know how much life is left in the other packs.

 

Is the Showtec Multi Exchanger any good as a reliable yet cheap replacement, or does it have quirks? Multi Exhanger image. I will have a lot of resoldering to do to convert it back to Socapex, as I wish not to use the d-sub connectors.

[richard_cooper]

Is the Showtec Multi Exchanger any good as a reliable yet cheap replacement, or does it have quirks? Multi Exchanger image. I will have a lot of re-soldering to do to convert it back to Socapex, as I wish not to use the d-sub connectors.

 

I installed one as a temporary fix in one of my venues about 2 and a half years ago, long term fix has still to happen, but it's been running (24x7) without a problem since then.

 

So much for temporary! I have no idea how well it would stand a touring/hire situation however.

 

Richard

[scjb]

I have no idea how well it would stand a touring/hire situation however.

Fortunately cheap enough to buy two... one active and one spare!

[Tom Baldwin]

I will have a lot of resoldering to do to convert it back to Socapex, as I wish not to use the d-sub connectors.

 

Since the Multi-Exchanger is only 1RU high, you'll need to bring the socapex out to a blanking plate or something similar. I don't think you'll fit a 37-pin soca on the back of it, due to the height limitations.

 

We've used two of them for a few years now, and haven't had any problems; the only quirk (which I've mentioned before) is that the channel test switches on our Betapack 1s no longer function when the ME72 is connected.

[Light Console]

Thanks for replies folks, all good then by the looks of things!

I am intending to bring the Socapex out to a blanking plate, the Demux lives in a 6ru box that was built for me, and is reasonably deep at the back, because that was where the positive outputs were on the Demux, so the extra space meant the Socapex was protected. I shall simply mount some reack strip and blanking plate at the back.

There is a connection in the 8 pins that isolates the test function, I can't recall which one though. I only know this because one of my cables only has 7 conductors, and still works, but lets the test function work as well.

[Andrew C]

I only know this because one of my cables only has 7 conductors, and still works, but lets the test function work as well.

Sounds to me like the supply pin on the rack may be connected to ground on the desk.

[ianknight]

I see my infamy precedes me... :** laughs out loud **:

 

It may well be that as the battery died and leaked, it started to corrode some of the PCB tracks and this has only just started to affect things.

 

It might be worth just popping the board out and having a squint (and easy to repair with some thin control cable cores) - also check for dry joints around the mains IEC inlet and the voltage regulator. Also - put a meter on the battery (without mains power) and check the battery - its not unknown for a rechargeable to fail before its MTBF.

 

The Multi Exchanger would be a worthy swap for the Demux as long as it's driving a decent rack - they don't like Mini 2's for a prolonged time or any rack that has an unbuffered input (so the Beta's should be OK).

 

As far as making cables for it - buy a fully wired 25D printer cable from CPC - chop it in half and bell through the cores/pins, then use that to make off to the Socapex. It's a lot easier than wiring the 25D (and getting the sequence wrong and having to de-solder it and redo it - anyone want a T-shirt!!) Just be careful when you do the 25D - the pins dont follow as you would expect e.g. down the sides in a line but jump across pin numbers i.e. Pin 2 is channel 2 etc.

[daifuse]

I replaced a failed Strand demux with a GLP multi-exchanger (I think its the same machine as the Showtec) and it's worked faultlessy for over 12 months. Pin-out was different on the 25 D connector but that was no problem to re-wire and also the output is switchable from +ve to -ve if you need it. There is also one in a local school which has been used (and abused) for over 2 years and still operates happily. It was certainly a lot cheaper than I expected and does the job.

[Light Console]

Damn, looks like I missed the last two posts, sorry chaps. I might have a look at the IEC area for dry joints as I remove the Socapex!

 

I have finally had the time to go and collect my new Multi Exchanger. First impressions are very good, it seems to spring to life very quickly, and feels robust enough.

 

Outputs are a tad odd, but I see why. They are not 1:1, 2:2... 25:dirt, but 13:1, 25:2, 12:3, 24:4... 1:dirt. Logical as you look at it, but not if you think of the numbers like I was going to do!

 

Am off now to see what bits I have in the loft to do the conversion. I will be back...

 

 

Edit: Oh, nothing helpful up there at all, a box of sockets, a bag of boots, but no plugs. Oh well, next week I see another order happening!