Tunze 5017 problem

[Jon Lazar]

Roger,

I returned from vacation to find my ATO stopped working. The control panel is dark. I tested the pump on a 9v battery and it doesn't work. I removed the pump and the 5017 control unit acts normally in all ways (proper green/yellow/red level sensing and audible alarm). When I reattached the pump, the control unit acts dead again.

I replaced the pump and the control unit acts exactly the same. I verified the new pump works with a 9v battery.

The 5017 is dated 07/2011. The PTC appears to have slight swelling around the pin. Not sure if that's normal. I jumpered the PTC with power on the unit and it still acts dead.

I've already purchased a replacement unit, but would like to repair this one as a backup. I'm looking for any recommendations on which component is the likely culprit. I'm capable of replacing standard-sized semiconductors.

Best,
Jon

 

[rvitko]

Their is a transistor near the PTC, usually this piece will appear brownish/charred if it is bad. It supplies 5V power to the board and optic sensor, the PTC rarely burns out, I would lean toward this transistor, but in my experience when this is bad there is a cascade of burned diodes and other issues. This will generally be caused by a bad pump, the PTC will cycle repeatedly but eventually this piece gets too hot and burns, the current board has a different safety and shuts off power completely, the controller will flash on and off from attempted restarts but it promptly detects the overload and shuts down again.

 

[Jon Lazar]

Thanks for your help, and that's probably the scenario here. I replaced the PTC because it looked bad, but this didn't fix the problem. I visually inspected all the components with a loupe and couldn't find signs of damage. It looks like I've done all the easy steps, so I think I'll put this in my box of spare and broken parts.

 

[rvitko]

FWIW, I would be willing to discount a new one if you were interested, I am unfortunately out of controllers and osmolators but more will be in next week.

 

[Jon Lazar]

Definitely interested. I'll send you a PM.