SCAD TM1 worked great… for one day

[Howler]

After a successful installation and numerous tests of a brand new SCAD TM1 level monitor for our holding tank, I returned to the boat the following day to find no response when tapping the display monitor. No lights come on at all. I checked all the electrical connections for proper voltage and continuity, and everything is fine. It’s as if the unit just stopped working.

Has anyone had similar experience? How can I troubleshoot this further (didn’t see anything in the documentation)?

Thanks.

[peghall]

Have you considered calling SCAD to ask them? 336-793-2003


--Peggie

[Howler]

Originally Posted by peghall

Have you considered calling SCAD to ask them? 336-793-2003


--Peggie

I will, Peggie. Thanks.

[markxengineerin]

SCAD tech support was quite helpful when I called, patient and knowledgable. The product, on the other hand, seems to perform differently depending on humidity/moisture levels. I am sensing through a large gap (double wall), so maybe other more conventional situations work better, but I've read others reports of accuracy trouble as well.

[Howler]

Update - Called SCAD. Mike was awesome and helped diagnose problem. To be confirmed, but it seems by tapping into a circuit that has a motor (electric head), the motor can accumulate charge when activated, then, when deactivated, discharge a voltage that's too high for the SCAD and fry the monitor. Since it's not an amperage problem the inline fuse doesn't blow. The solution is a diode between the + and - power supply wires. Sending the monitor back for verification and repair/replacement.

[Bycrick]

Snubbing diodes have been good engineering practice on inductive load circuits almost forever. When I bought this boat, there was an indicator light for the propane solenoid. Very quickly it didn’t work. Aha! I’ll put in an LED, that will fix the problem. It lasted about two weeks. Being busy with other things, I just kept replacing it for a while. After much wasting of time and effort, I realized the back-EMF from the propane solenoid was high enough to burn out the LED. Since the installation of $.25 diode, the LED has lasted 21 years.