danfoss 550A controllers

[cold.man]

anyone had any problems with these danfoss 550a controllers, i have found 3 now that are not sending 240v to akv coil.
in parameters
relay for cooling says its on but no 240v feed it seems as the relays in these controllers are crap.
changed the controllers now they are working fine, anyone else had this problem?

[pcbfix]

Got anyone to repair your old controllers yet?. Have seen problems with 514B 230V dc AKV output burning out. The 514B uses MOSFETs to pulse the AKV. The 550 probably uses a solid state relay or equivalent circuit to pulse the 230V ac AKV. If the 3 boards your talking about are new, then there may be what's known as a "Test Escape" in the testing process.

If the boards have been in use for a while, then someone may have come along and replaced 3 AKV's because they went faulty and not realised the faults may have stressed the boards they were connected to, so a couple of months later the boards fall over.

I've seen things like this happen in other products, but I don't personally know what the failure rate of AKV valves are.

Cheers

pcbfix

[750 Valve]

240V AKV coils have a pretty low failure rate given the number out there and amount of pulses being done per year.