DMX to Scrollers

[Robertdazzler]

Hi All

 

Problem: ColourMag scroller PSU fails to give out DMX to scrollers and doesn't seem fixable. I have tried sending desk DMX directly to scroller but no joy. I have thought about bypassing the ColourMag DMX aspects with a DMX splitter to give a stronger signal but DMX is 3 wire and only 2 wires go to 4 wire scrollers other 2 are for dc power. can I do this and how do I perm 2 from 3. do I ignore the data common?

 

 

 

[patrick_keys]

Hi All

 

Problem: ColourMag scroller PSU fails to give out DMX to scrollers and doesn't seem fixable. I have tried sending desk DMX directly to scroller but no joy. I have thought about bypassing the ColourMag DMX aspects with a DMX splitter to give a stronger signal but DMX is 3 wire and only 2 wires go to 4 wire scrollers other 2 are for dc power. can I do this and how do I perm 2 from 3. do I ignore the data common?

 

Disclaimer: I don't have one of these, but the DMX data is sent as a balanced (i.e. 2-wire) signal. If you're bypassing the PSU, you can connect the screen wire of the DMX cable to the negative side of the PSU - but it's really only used for shielding - it isn't strictly required for data transmission.

[alistermorton]

Does this page help at all? It expands on what Patrick said.

[Brian]

...and doesn't seem fixable...

 

Everything is fixable.

[MarkPAman]

Tell that to Humpty Dumpty.

[Jivemaster]

It's highly likely that the DMX screen is the ground wire in the scroller PSU 4 core, think that it might be common and +v and data+ and data- common being common to power and signal.

[Brian]

Tell that to Humpty Dumpty.

 

That's what happens when you demonstrate the second law of thermodynamics without fully understanding what it means.

[theatretechie]

Its my understanding that Colormap scrollers were not straight DMX.

 

Wasn't there a Converter inline for their control protocol allowing DMX control?

 

Best guess, from the time I owned Gelstream Scrollers, would be to check and or change the DMX Chip in the converter. Older chips seemed to be vulnerable to failure after a long time of no use.

At least that was the case with the Gelstreams.

 

Hope that helps a little towards your fault finding

[Robertdazzler]

Its my understanding that Colormap scrollers were not straight DMX.

 

Wasn't there a Converter inline for their control protocol allowing DMX control?

 

Best guess, from the time I owned Gelstream Scrollers, would be to check and or change the DMX Chip in the converter. Older chips seemed to be vulnerable to failure after a long time of no use.

At least that was the case with the Gelstreams.

 

Hope that helps a little towards your fault finding

 

Thanks for advice. The power supply I have contains a hand made circuit board with circuitry to modify the DMX signal. It has provision ( also hand added) to have a start address which I can just about understand but this is a programmable in circuit device i.e. a PIC and I have no chance of knowing what the software is. the PIC appears to have died. I cannot simply change the chip because it seems unique unless you know someone who has already done this. I have tried bypassing the PIC altogether which limits address on the scrollers to 99 but without success. things are not looking good. Do you think some other brand of power supply could save the day?

[richardash1981]

Thanks for advice. The power supply I have contains a hand made circuit board with circuitry to modify the DMX signal. It has provision ( also hand added) to have a start address which I can just about understand but this is a programmable in circuit device i.e. a PIC and I have no chance of knowing what the software is. the PIC appears to have died. I cannot simply change the chip because it seems unique unless you know someone who has already done this. I have tried bypassing the PIC altogether which limits address on the scrollers to 99 but without success. things are not looking good. Do you think some other brand of power supply could save the day?

Can you post a photograph of the hand made board? I'd be surprised if what you say is the case because almost no programmable chips will connect to DMX lines directly:

• If there really is only one IC on the circuit board, it more or less has to be an RS485 line receiver, in which case it can be changed or an alternative found.
• If there is a small RS485 receiver and a larger programmable chip, then the line receiver is the more likely one to be dead, and it's worth changing (or testing) before concluding that the programmable chip is dead.

[Robertdazzler]

Thanks for advice. The power supply I have contains a hand made circuit board with circuitry to modify the DMX signal. It has provision ( also hand added) to have a start address which I can just about understand but this is a programmable in circuit device i.e. a PIC and I have no chance of knowing what the software is. the PIC appears to have died. I cannot simply change the chip because it seems unique unless you know someone who has already done this. I have tried bypassing the PIC altogether which limits address on the scrollers to 99 but without success. things are not looking good. Do you think some other brand of power supply could save the day?

Can you post a photograph of the hand made board? I'd be surprised if what you say is the case because almost no programmable chips will connect to DMX lines directly:

• If there really is only one IC on the circuit board, it more or less has to be an RS485 line receiver, in which case it can be changed or an alternative found.
• If there is a small RS485 receiver and a larger programmable chip, then the line receiver is the more likely one to be dead, and it's worth changing (or testing) before concluding that the programmable chip is dead.

 

Hi

 

Thanks for your interest. I have photos but being new to Blue Room cannot figure out how to post photos to you. The hand made circuit has 4 ICs: reading from l to R one generates a -5V supply , next is the input driver, next is a microprocessor for I guess fixing the start address. there is a 3 decade switch on the power supply front panel. last is the driver out to the scrollers. My oscilloscope suggests that the input IC is working but no signal is being sent to the output driver IC hence I believe the microprocessor has died. if you can school me in sending photos. I can feed you more.

 

 

 

[DrV]

Best bet is to upload the photos to a publicly accessible server then post a link to them

Dave

[IRW]

Thanks for your interest. I have photos but being new to Blue Room cannot figure out how to post photos to you.....if you can school me in sending photos. I can feed you more...l..

 

Upload them to an image sharing service such as Flikr or Photobucket, then post a link here.

[Robertdazzler]

Hi

 

If I have done this properly you should find photos at http://s1055.photobucket.com/user/merlin79/library/

 

I still think the microprocessor has died. I am guessing that its purpose is to set a start address as the scrollers can only handle up to 99 and the 3 digit selector can handle 999 as a start address. If that is so I should be able to hook the input driver chip to the output driver or use some off the shelf RS485 to 422 converter. what do you think.