problems with a dmx light

[paulears]

<particle physicist>

Neutrons are charge-less particles and do not flow. I think you mean electrons. Strictly speaking, you're talking about inverting the phase, not reversing the flow.

 

</particle physicist>

 

Ricky, if you could be a little more specific in your posts, you would recieve a better response, rather than speculations and pedantic comments from people like me...

If pedant mode is on, then we are talking about reversing polarity, not phase.

[ChrisD]

If pedant mode is on, then we are talking about reversing polarity, not phase.

 

Isn't swapping the data pins inverting the phase? One pin is always "high" when the other is "low" I believe, hence the need for twisted pairs, so the interference can be cancelled by summing the phases at the other end. Polarity is more of a DC thing rather than an AC signal. Or have I got the wrong end of the rather pedantic twig?

[J Pearce]

Technically inverting the phase and changing the polarity are only the same with constant frequency sine waves.

 

Phase angle is the difference between peaks in two otherwise identical signals.

 

I'm struggling to find a full definition for polarity, I blame extortionate amounts of coursework draining my mind.

 

[edit]

 

Actually the cancelling of noise is usually done by using difference amplifiers.

By only amplifying the difference between 2 lines, anything present on both lines is nulled.

[soundo26]

My bad, Light Console! I would've expected better from the beeb. I guess that kind of shows my age, or lack thereof.

 

Errrr!!!...............Have you set the DMX address correctly????????

[paulears]

The polarity.phase thing has been causing explanation problems in the audio field for ages - the generally accepted thing now is that the button marked phase on a desk channel simply swaps the hot and colds around (as in swapping pins 2 and 3 on the input). As phase is related to time then doing this swap doesn't alter the actual phase at all - for this to happen the signal would have to be advanced or delayed by (on a sine wave single frequency 180 degrees - something that doesn't happen. Soundcraft, on the series five say this "the Phase (ø) switch reverses the polarity of the selected input" - sort of a cop out, because we have used the term phase to do this for ages, gradually it is going. Allen and Heath have already started re-labelling the button as polarity.

[Ricky]

I have tried swapping the data pins, checked and I have set the address corect. still no luck how do I diagnose a blown DMX chip??

[paulears]

have you tried what we suggested - is it just one function, or do others not work.

 

with base address at 1 and a one to one patch, list what features work and what dont and post tem - you don't give us much info to work on.

[david.elsbury]

Urgh, the La Bomba. At last something I have experience dealing with!

 

The 1/4" jack is for a remote control, not audio. If you want to feed audio to the unit, you'll need to come up with a hack to replace the electret mic.

 

The light only has two channels of DMX -

- Mirror rotate

- Colour/Gobo/ Shutter

 

Based on my experience with them, I'd check that the soldering on the dip switches is all OK.

 

Adressing is the same as with most DMX lights... so nothing special. Switch 10 is some sort of option, I think it relates to stand alone mode so leave it "off"

 

HTH somewhat.

 

David

 

Edit: and no need to phase/polarity reverse /swap the data pins. (just to get this back on topic a bit! :unsure: <_< )

[Ricky]

Thank you I have got round the sound input by putting a jack in place of the mic and this works and will try checking solder joints

[Ricky]

Hi all im back and still having problems ive checked all the solder joints, they are fine, ive checked the wiring and thats all fine even the swapping of the pins which this light needs for DMX, But it still wont respond o any DMX controls can anyone help?

[jayselway]

Hi Ricky,

 

When you are trying to control the unit over DMX, is it still responding to sound, as if there was no DMX going into it? If so, try turning off DIP Switch 10, which would put the unit into Sound > Light mode. If I remember correctly, you can feed DMX into these units all you want, but if switch 10 is on, they'll still be in Sound to Light mode, and ignore the DMX.

[Bean]

Go though each part of the setup.

 

Is the desk outputting DMX? (Test by trying a diffent DMX device)

 

Are the cables good? (Same test)

 

Is the DMX address correct? (Did you read the dip switch up-side-down?)

 

If all that is good, I'm out of un-mentioned ideas.

[jayselway]

Just to check: when you are setting the DMX address on the dip switches, you are doing it in Binary aren't you, so 1, 2, 4, 8,16,32,64,128,256 -

 

e.g. not switch 3 for address 3 (should be 1 & 2)....Just a thought there.

[Owen Radmore]

Have you ever had this light working with DMX before?

 

Or other lights working with DMX before?

 

Is the DMX line terminated some light have a terminator built in?

 

The DMX line should always be terminated at the end either with an in built terminator on the device

or plugging a terminator into the DMX out of the last device.

 

Hope this helps.

[Shez]

Just to check: when you are setting the DMX address on the dip switches, you are doing it in Binary aren't you, so 1, 2, 4, 8,16,32,64,128,256 -

 

e.g. not switch 3 for address 3 (should be 1 & 2)....Just a thought there.

 

It's actually BCD (binary coded decimal) rather than binary :huh: