AF1000 Issues

So I have an AF1000 that seems to be blocking DMX from downstream devices when it's plugged in. Looking at the schematic, it shows that the relay should switch the dmx out to be driven by the line driver IC when it gets 5V. I verified that the relay is doing that, so I figured (since the AF1000 responds to dmx itself) the only thing it could be is the line driver. I replaced that chip, and in the shop, with no lamp installed, was able to get a trackspot connected downstream from the AF to respond to dmx whether it was plugged in or not. Assuming it was fixed, I took it back to the club I work at, put a lamp in it, and put it back up on the truss... and I'm still getting no response from downstream devices when the AF is powered on.

Would a lamp make a difference as to why DMX isn't passing through? I don't see anything in the schematic that makes me think that would be the case.

On the bench, when I plugged it in, there was 5V applied to the relay coil, and i checked the relay contacts to make sure it switched. It did.

I also checked the schottky diodes with a diode checker, and got an average diode drop (~.6V) accross them, so I think they're ok.

Any ideas?

Jeff
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    Did you test the relay *in the same orientation* that it would be in when hung? The relay may still be the problem . . .

    - Tim
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    Thanks for the input. I don't believe the wiring or the connectors to be bad, since unplugging just the AC (and thus de-energizing the relay) allows dmx to loop through perfectly, it's only when the strobe is plugged in, and the relay is energized that I have a problem.
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    Looking at the schematics, this is just about the exact same circuit that is in the Intellabeam, and I had the same problem, and went down the same road you are on . . . . changed the chip, the diodes, checked all the traces . . . and found that the relay just wouldn't make contact when powered up - all data was fine until powerup, then *blat* . . . dead loop downstream . . .

    I agree that if you get data when the fixture is not powered, then you can pretty much rule out all interconnect wiring, the connectors, and the paths from the connectors to the relay. If you can verify that there is continuity from the driver chip pin 3 to R31, and R31 to the relay, as well as chip pin 2 to R88, and R88 to the relay (and that neither D34 or D35 is shorted to ground, then it's got to be the relay . . . Or, if you are comfortable probing around with it powered up, check continuity through the relay with power applied. Since the signal path into the AF1000 is common to the data pass through, if it works, then short of a foil break feeding the driver chip, the above mentioned parts are all that is left . . . . pretty simple, but unlike a mover, more high voltage to dodge when inside . . .

    - Tim
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    Used to work on vidicon video tube cameras just out of High School.. the High Voltage doesn't bother me that much ;).

    Anyway, I think, since I was able to pass data with the strobe energized while it was on the bench, but not while it was on the truss, that your suggestion about orientation makes the most sense at the moment.

    Thanks for all your help. I'll look at the relay again next.
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    If this is the same relay as I have seen (5V dip relay) I got the part for mine for about $2, so it's not like it's a huge expense . . .

    - Tim
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