Problems with Demux48

[skippa]

Hello

I use a Demux48. since the last few weeks the device did not start correctly. I think it was caused by the low temperatures in the dimmer room (maybe 0 to 5 °C). When the temperature in the dimmer Rack / Room rises up in the evening i can start the demux48 device normal (starts up with testing all LED-segments, then showing the start-adress).

No i changed the battery to a new one (3,6V NiMH, 140mAh), but now the device never starts correctly. i measured the voltage at the battery an detected that the voltage is going slightly down, seems like discharging. I soldered ist aout of the PCB an checked it - the battery seems to be OK, out of the PCB the voltage rises up to its normal 3,6V.

Whats wrong with my Demux48?!

 

greetings from germany

 

MArtin Knott,

 

MAxdisco (www.max-kiel.de)

[KWR88]

I think we have been communicating directly by e-mail as well.

Did you manage to obtain a crystal for the unit?

[Steamyrotter]

Hi

 

Sorry to resurect an old thread.

 

I have just obtained a Demux48 and seem to have similar probems with the start up.

 

When powered up only the recieve and error leds light and then it displays 012. Nothing works after that.

 

does exactly the same with and without a DMX stream flowing through.( although recieve LED illuminates ok so it is seeing something)

 

Tried to change channels, and Scurves but nothing will play.

 

Unit has one negative o/p board on the last 4 banks. Tried with this plugged in and out. Also removed the display board and reinserted to see if it's the connector but no change.

 

Also checked resistance of the push buttons and they are good.

 

Any thoughts??

 

Thanks in advance

[KWR88]

You have not mentioned if you have checked the battery on the unit or not.

I would start with that. You need at least 2.2v on the battery with out power and below 4.2v with power or the RAM does not run.

 

The other component that can cause the same sort of problem is failure of the clocking crystal.

[Steamyrotter]

Thanks for the reply.

 

Yep Battery is flat!! 8O

Shows 0.4v off and 6v when powered so definitely up the spout.

Whilst there checked the bus volts and they look oK +-24v & 11v.

 

I'll get a spare and try that, & let you know how i get on.

 

I'll get a scope on the xtal after I have replaced the battery to prove/disprove that.

 

Thanks

[Steamyrotter]

Hi Keith

 

Have now replaced the battery and hey presto.

As you would probably expect, it now does what it says in the manual.

Nice easy fix that.

 

Next thing to do is ensure I have the leads set up right for our (sorry) Strand Act6+ racks, using the negative supply module.

 

Going to try a little jiggery pokery with a VB prog I have written for our panto this year.

 

Many thanks

 

D.

[Pseudofrog]

I've recently bought an "Excellent Condition" Demux 48, off a well know auction site. Unfortunately the unit was not as described in the listing and when used it became evident that it was faulty. When switched on the unit goes through the normal config procedure, and indicates DMX Address 001. After a variable amount of time, the readout goes nuts, Address values increasing and decreasing, then flickering on and off. If it is attached to dimmer all outputs seem to be 100%. It does not respond to DMX. Any help on this would be appreceiated.

[Steamyrotter]

However when i finally tried it........................................

Not a dicky bird on the outputs so resigned it to the "things to sort out when i get time to look at it" pile and reverted to the analogue desk.

 

Traced the problem to a faulty transistor and IC due to the old battery contents dumping themselves everywhere. :cry:

 

Given a good cleanup and got chans 25-48 working but 1-24 are not playing.

 

Found the problem but need the transistor number to replace. (Transistor supplying the LM324s pin 4..

 

Hope someone can help????

 

Cheers

[KWR88]

I think that I have again already contacted you directly.

Transistor is an ZTX213, if you can not get these then a ZTX214 or BC213.

 

You will also need to replace the LM324 to get the negative output for channels 1-4 as well.

[Steamyrotter]

Keith

 

Many thanks

 

Got your mail as well.

There is slightly more damage than i first thought but getting there...

 

Cheers

[lemon]

Hi all

I think - not shure that I have the same Demux - I d need manual -operation and if availiable maintenance

(Circut)

I had the problem with the batery (accu)

it was defect- I put a zehner diode instead the accu in it because without Battery it did not work anyway.

But now when the demuxer is powered on display apears and everything is OK intil i disconnect the DMX signal

and the demuxer comes with some channels on - not the same as DMX was.

 

See pictures if it is the right board

Thanks