Martin Jem ZR33 --- Ready led

[Ed Kaz]

Boy its starting out to be a rough year....

I have a Jem ZR33 fogger that works when it wants to...

The ready led on the back works intermittently. 

When powered on and after heat up it would come on and work fine all night. 

Next night ... turn it on, it heats up(>30mins) (can feel heat thru from front of unit)...

NO "ready" led  

No Fog output

Checked "thermo breaker" under front cover ... not tripped.

Next night works fine?

Has anyone worked on these bad boys or any ideas on what to look for.

 

Thanks

Ed

[indyld]

Assume it's similar to various Martin/Jem models I've worked on. Given the symptoms described, it would appear that perhaps the unit doesn't realise it's at temperature. This is usually dealt with by a circuit that includes a thermo couple that I think is built into the heater block and isn't individually replaceable. This is from somewhat dodgy memory without one in front of me, and I may be mixed up with other manufacturers products.

Check the connections from the thermo couple first.

I've also had things such as components on the main PCB, the DIP board/module and even dodgy main supply cables to the heater block (runs through the thermal cutout).

But the lack of ready LED with an actually heated block would suggest looking at why the machine doesn't realise it's hot.

Be careful inside these things when powered, there are nasty voltages in unexpected places.

Edited January 6, 2022 by indyld

[timsabre]

The control of ZR33 is entirely done by software, it checks for most likely problems with the thermocouple and won't heat up. So it could be an intermittent problem with the thermocouple connection as Rob suggests.

Where is the remote for this machine - docked in the back of the unit or on a long wire? The "Standby" button on the remote must be pressed to make it heat up, if there is a problem with the connection to the remote then that could result in it not heating or heating intermittently. If the remote is on a long wire I would try plugging it directly into the back of the machine and see if that fixes it.

I am not sure if you can call Jem Service directly any more since they were assimilated by Martin and then Harman but if you can get to talk to them they would know the answer to this, quite a few of the original team still work there.

[indyld]

1 hour ago, timsabre said:

I am not sure if you can call Jem Service directly any more since they were assimilated by Martin and then Harman but if you can get to talk to them they would know the answer to this, quite a few of the original team still work there.

There is still knowledge available through the distributor, as suggested there are people still about that know their stuff. My most recent chat with them was a particularly tricky issue with an AF1 (which as some will know uses the same smoke machine PCB) and they were very helpful with what they knew. Although were unable to find a particular schematic that would have really helped.

One thing Tim's comment reminded me about which I forgot to mention is that the control module (DMX or Remote) can be the source of bad things happening in general. I'm lucky enough to be able to swap out others from stock but if you only have one machine then it's harder eliminate that particular weak point.

Edited January 6, 2022 by indyld

[timsabre]

I wrote parts of the firmware for ZR33 and ZR44 but I am mixing them up in my brain - I think ZR33 had dip switches and a separate DMX interface which sent analog to the main board, but ZR44 had a digital interface panel with the DMX integrated into the mainboard.

If it has a separate DMX->analog module, those sent out a "standby-active" voltage of 1V when DMX was received, which would cause the machine to heat. 1-10V then would give varying levels of smoke. 0V would shut down the heaters. This was combined with the voltage from the remote, highest voltage takes precedence. But I might be confusing it with other Jem products. I think the remote might have been on a 3-pin XLR using a digital protocol to connect rather than the voltages used previously.

[Ed Kaz]

Thanks for all your help. I will try to call Martin (or whoever is there now).

The remote is directly plugged into the back and unit does have dip switches for DMX.

Like I said its an intermittent problem and ONLY does NOT work when I need it the most...

[alistermorton]

You're right about the remote using a 3-pin XLR, Tim. Having sent it down an audio snake (once) I don't recall hearing digital interference.

[timsabre]

Jem's digital remote protocol is just 5V serial at 1200 baud. I wouldn't expect to hear any noise. On the other hand I think some of them had 0V and power on 2 of the pins and sent a 0-10V analog signal back down the 3rd pin to control the machine - I think that is why there isn't a "ready" light on the remote.

[Ed Kaz]

Technical Support Engineer Harman Professional Solutions:

"I would inspect all connections to the thermal switch (you will need to pull back insulation to expose wiring around thermal) and main PCB.  We have seen the connections deteriorate over time and have to be redone "

 

I just have to get to venue and get it on the bench...

[indyld]

13 hours ago, Ed Kaz said:

"I would inspect all connections to the thermal switch (you will need to pull back insulation to expose wiring around thermal) and main PCB. 

I have had this too. The spade connectors and/or the terminals themselves on the cutout degrade and need remaking or switch replacing. The switch is in series with the Line conductor and could result in impedance that means the block never reaches temperature, although seemingly hot.

Edited January 7, 2022 by indyld
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