CHAUVET Arena Hazer 3 DMX issue

[alistermorton]

It looks to me, from that photo, as if it was indeed the right way around when both the ramps were in the same orientation. Also, the reversed connector no longer fits inside the screenprinting, which is further circumstantial evidence that it's now wrong.

[DrV]

The moulding certainly looks wrong now so you should put it back. You said earlier that you had found which pin on the main board Molex was logic ground. Regardless of wire colours or connector orientation, that pin must connect through to opto pin 5. Once you've identified that pin and got a solid connection the position of the other wires will follow on from there. How about you show a picture of the connector on the main board and point out which pin connects solidly to logic ground.

Also show a picture of the wiring harness showing both ends.

[partyanimallighting]

OK. I'm happy that I did not make the error of reversing the Molex connector but I firmly believe that the original problem was that hard to find short on the 5 PIN harness. I was doing some measuring as you requested and the problem popped up again and on checking, the insides of a couple pins had a little corrosion so I'll change out the Molex terminal on the mainboard completely to resolve the problem once and for all. New terminal. New harness wires. I've traced the 5 wires as requested to their continuity points on the pin terminals for the 75176 and the OPTO and took the pix as requested. My next step is to remove the old cruddy Molex connector on the mainboard and replace it with a new connector to get rid of the short once and for all. Then, if you guys think I should, I'll replace the opto and the 75176 and test. I suppose if there's still an issue with the DMX function, the chips are fried. I'll be able to source a 75176 easily but the opto will be a problem to source locally. Let me know what you think will be the best way to proceed. And thanks for all the help so far. I've once again learned a lot!

 

Edited December 10, 2022 by partyanimallighting

[partyanimallighting]

OK, the 5 PIN Molex was changed out completely and I reconnected the mainboard and the 5 PIN harness to check for for continuity to logic ground and the other connection points for GREEN, WHITE, BLACK and YELLOW at the opto and 75176 pin seats and all is fine, full continuity all all relevant points even with the harness wire jiggled wildly. I then powered up and checked for voltages at PIN 5 and 8 on the opto seat and PIN 2 (3,4, and 5) and 8 on the 75176 and both give good readings of 5V. Do I replace the chips and test? Could that faulty harness have caused me two weeks of stress?

[DrV]

Provided the voltages are the right polarity (-ve meter lead to pin 5 in each case should give you a + reading on the meter) then it's time to put the chips back.

To do this truly step by micro-step I would replace the 75176 first and verify that it works using my 1.5v battery test as follows:

1) replace chip with a new one. It was probably the source of the original problem.

2) Connect the boards together and power on.

3) Connect a 1.5v battery between XLR pins 2 and 3, +ve to 3 and -ve to 2.

4) measure between pins 5 and 1 of the 75176. You should see about 4 to 5 volts.

5) connect the battery the other way round.

6) measure between pins 5 and 1 of the 75176 again. This time you should see less than 0.5V.

If all those steps work as described then the 75176 is working correctly, as far as one can tell without a scope.

Now replace the opto and try it for real with a DMX signal.

If it works, pat yourself on the back and drink a long one!

7) If it doesn't work, repeat steps 3, 4, 5 & 6. to find out whether the opto is dragging the 75176 output down or up.

8.    If step 7 works ok then repeat steps 3, 4, 5, & 6 but this time measure the voltage with the -ve meter lead on logic ground and the +ve meter lead on the middle pin of the Molex connector. You should get similar results although the voltages won't be exactly the same.

If that test, step 8, doesn't work there is more that you can do. However, it's already complicated enough so let's see the results first.

Edited December 10, 2022 by DrV
Putting 8 with a parenthesis after it gets replaced with a smiley!

[partyanimallighting]

I tested as you asked with the new 75176 installed (no OPTO) and without powering up I checked voltages at the DMX solder points PINS 2 and 3 and got 1.6V as expected from the battery and 0.37V and 0.35V with the battery wires normal and reversed respectively. On powering up, at PIN 5 -tive and PIN 1 +tive it reads 4.65V and with battery polarity reversed it reads 0.135V so this seems correct based on what you stated to expect.

I then installed the OPTO and checked voltages from the battery at the DMX solder points PINS 2 and 3 and got 1.6V and without powering up I got 0.14V and 0.27V at PINS 1 and 5 on the 75176 respectively with battery leads normal and reversed . On powering up, at PIN 5 -tive and PIN 1 +tive it reads 0.196V and with polarity reversed on the battery it reads 0.39V so it seems that the OPTO is "dragging down" the voltage. Just to be sure I then tested via DMX control and still nothing. I then removed the OPTO to double check the voltages at the 75176 and got the correct readings as before, 4.65V and 0.135V respectively. I then tested the voltage from logic ground to PIN 3 on the Molex and that's 4.9V.

Soooooo.....is the OPTO the guilty component and do I order a new OPTO?

[DrV]

Well, the results are slightly odd; it shouldn't be possible for the opto to pull pin 1 of the 75176 down, only up. However if the opto is so badly damaged that the isolation barrier has broken down then it is conceivable that it could load the input side. Anyway, it certainly appears to be toast so you'll have to get hold of a replacement.

As a matter of interest, once you've removed the opto from the board put your meter on ohms and check between pin 3 and all the other pins (of the chip). They should all be open circuit (OL) except pin 2 which might show something.

[partyanimallighting]

I metered the OPTO for continuity first and every pin is OL from PIN 3. I then checked resistance from PIN 3 -tive as you requested and, as you said, OL across all pins except for PIN 2 (0.9 M ohms). I then ran a diode test across PINS 2 and 3 and got 1.29 and OL. Are these readings consistent with the OPTO being fried?

 

Edited December 12, 2022 by partyanimallighting

[DrV]

No, those are consistent with it being ok. Internally there is an LED between pins 2 & 3.

Is there any possibility that you shorted something when you put the opto back? Or put it back the wrong way round?! Sorry but I have to ask.

Given that the LED seems ok it is very difficult to see how putting the opto back would give you that set of results. Even if the opto doesn't output correctly it shouldn't (can't) drag down the output of the 75176.

All I can think of is that you put the opto back, turn the power on and repeat the battery tests and also check that there is still 5volts between pins 5 and 8 of both chips.

[partyanimallighting]

Of course you should ask. It's been a lot of posts but the orientation would have been correct. And after replacing the opto I was sure to clean up the solder points. I'll go through the process again and report back here.

[partyanimallighting]

I took some more readings so here goes.

NO OPTO CHIP. POWERED ON

OPTO PINS 6 +tive and 8 +tive 5V (PIN 5 -tive probe)

75176 BATTERY TEST PIN 1 +tive 4.5V

                                     (PIN 8 +tive 5.1V)

BATTERY TEST REVERSED PIN 1 +tive 0.155V

                                              (PIN 8 +tive 5.11V)

This seems to be correct to what you said to expect via the battery test.

WITH OPTO INSTALLED. POWERED UP.

75176 BATTERY TEST PIN 1 +tive 4.6V

                                     (PIN 8 +tive 5V)

BATTERY TEST REVERSED PIN 1 +tive 0.4V

                                              (PIN 8 +tive 5V)

OPTO WITH BATTERY TEST PIN 1 +tive 0.1V

                                                PIN 8 +tive 5V

OPTO WITH BATTERY TEST REVERSED PIN 1 +tive 5V

                                                                   PIN 8 +tive 0.19V

The voltage from logic ground to WHITE wire is 4.9V.

I hope this helps.

Question. Is there the possibility that the display for this unit is maybe not holding the DMX address? Could this be an possible cause to the "no DMX" issue?

[DrV]

Forget about DMX addresses until we've verified the interface PCB.

There is one more sequence of tests:

Meter -ve on logic ground.

Meter +ve on the white wire.

Connect the battery one way round and you should get less than 0.5V.

Connect the battery the other way round and you should get more than 3V (probably about 5V).

If those results are correct the interface PCB is working correctly as far as we can tell without a scope.

Then you can reassemble it and see how it responds to DMX.

[partyanimallighting]

14 hours ago, DrV said:

Forget about DMX addresses until we've verified the interface PCB.

There is one more sequence of tests:

Meter -ve on logic ground.

Meter +ve on the white wire.

Connect the battery one way round and you should get less than 0.5V.

Connect the battery the other way round and you should get more than 3V (probably about 5V).

If those results are correct the interface PCB is working correctly as far as we can tell without a scope.

Then you can reassemble it and see how it responds to DMX.

 

[partyanimallighting]

Well, no need to test via DMX I suppose. I tested for voltage at the WHITE wire from LOGIC GROUND with the battery test. 4.9V both ways. No voltage drop at all. Does this once again point to the OPTO?

[DrV]

3 hours ago, partyanimallighting said:

Well, no need to test via DMX I suppose. I tested for voltage at the WHITE wire from LOGIC GROUND with the battery test. 4.9V both ways. No voltage drop at all. Does this once again point to the OPTO?

If you're sure that all the wires were in place and you had your meter connected to the right place then yes, it does mean the opto is faulty. To be absolutely thorough you could check continuity from the white wire to pin 6 of the opto but it does sound as though you'll need to procure a replacement.