Martin MP-2000 Fog Machine problem

[partyanimallighting]

Hi guys, I'm back with another faulty unit. This time it's a Martin MP-2000 fog machine, a really big unit used to fill large stages and clubs with dense fog. The unit consists of a remote control which plugs into the PCB and a 110V heating element and a 110V pump which pumps the fog fluid into the heater to create fog when the heater reaches the correct temperature after heating up. There is also a sensor which connects from the heater to the PCB to send a signal when the heater reaches the correct operating temperature. The remote plugs into the rear of the fog machine, into the PCB and, when the unit is switched on, a red power LED lights on the remote and two red LED's light on the PCB, "Power On" and "Heat", signalling that the unit is powered on and the heater is heating up. The green "Ready" LED comes on when the heater reaches the correct temperature and fog is produced by pressing the "Smoke" button on the remote. Based on everything I've learned concerning repairs from you guys, I think the BTA12 Triac will supply the pump and the BTB24 will supply the heater which has a high amperage draw and the 7805 supplies 5VDC to the PCB via the 110V/10.5V transformer. And that's where my smartness ends...... The PCB with issues does not function at all. When I connect it to a known working unit, the red "Power on" and "Heat" flash intermittently which indicates an error, and the machine does not go to the "Ready" stage. Where can I start?

 

[Martaine2005]

Hi partyanimal.
You say you have checked the board on a known working machine.
Have you checked the controller on a known working machine?
That is a fairly common fault.
Also, there is a procedure to reset the thermal fuse in the manual.
Martin

 

[partyanimallighting]

Hi Martaine2005, I tried the problematic PCB with a remote from a working machine which came in to repair a burnt out heater lead. It's simply a process of unscrewing some screws from the back plate and disconnecting the pump, heater and sensor leads and the entire plate with the PCB comes out so I simply swapped out the problematic PCB with back plate with the working PCB and connected the working remote to test, with the results above. I've had lots of problems with these units in the past, terminal burnouts on the heater leads, faulty pumps, failed PCB's and failed remotes so I know the usual problems to look for.

 

[partyanimallighting]

Hi guys, I haven't gotten any feedback so far but I've made some headway with this unit. It seems that the 110VAC/10.5VAC power supply is faulty and it's only outputting 3.75VAC so I found a suitable replacement off another PCB and swapped it out. I then powered it up and the unit seemed to function fine, the red "POWER" LED lit up along with the "HEAT" LED so all seemed well. I then checked the voltage at the heater block terminals and I got a good reading, 120VAC. Then.......there was a burning smell and the BTB24 600B started to smoke so I immediately switched off and unplugged to prevent any fire. I then took ahold of the BTB24 with a bird beak pliers and it was so hot that it slipped cleanly out of the solder points on the PCB. So....I'm right back where I started from. I'd really like feedback and assistance with this one PLEASE!!

 

[Alec_t]

Sounds like the BTB24 (triac) is being asked to pass excessive current. Have you checked that the heater isn't short-circuited? Can you check its resistance against that of a known good heater?

 

[partyanimallighting]

The PCB in question was tested on a known working unit so I'm pretty sure that the heater's fine. I will however, take some measurements and post the results just to be sure.

 

[Martaine2005]

Hi,
This probably has nothing to do with it but!
The AC line in side of the board. The solder joints look really dry. That fuse holder looks terrible too.
It could be shadow on the photo, but a good clean and reflow of those joints would not harm. High resistance could result from these.

Martin

 

[Braem]

Hello,

I have also one issue with this. (my model is in 220v but probably the component after the transfo is the same, and it's exactly the same of your picture)

For the pump alimentation I have always 19v directly and the pump is always trying to run.

Have you changing the Triac BTA12 to solve your problem ?

Thanks for you feedback.

Jean-Charles