I've done some more research into what I think that circuit is and I agree with you on that. I'm an electrician, not an electronics engineer, but if that mains dropping capacitor is getting weak, perhaps the breaking of the coils circuit momentarily induces enough voltage to get it over the minimum pull in voltage required. Just an semi-educated guess.
From what I can see, the board is quite simple and should be repairable, but it wouldn't be fun to re an re for sure. Garaventa told me it is not repairable and has to be replaced (for ~$3000.00 CDN). When I asked them why it failed they told me that it was an over voltage on the supply side. This was without removing the board or testing anything. When I requested more information from them they have chosen not to return my calls or e-mails.
I smell a rat. My measured voltage is and was 122/244V, well within our utilities acceptable limits. If indeed the board was damaged with this incoming voltage then there is something wrong with the design.
I have been using the trick of pulling one of the PF relays and replacing it to get things going again, but I'm afraid that sooner or later this might not work any more. The sockets of the relay socket might lose their tension, or I might break a relay pin off. We don't often get long outages, but we get a fair number of short ones, less than a few minutes or more often, just enough to blink the lights. Probably caused by a recloser operating if a branch or something shorts the high voltage lines.
Other than this fail to reset after a power outage, the elevator seems to function satisfactorily. Having said that, I don't think the emergency lowering function was ever tested on commissioning, there certainly is no record of that. The little UPS seems to be functioning but the lowering function doesn't work when I tried it. I do have some of the electrical drawings and the installation guide that I had to make sure the shaft was the right dimension. They left no operating manual, troubleshooting guide, or even a list of the trouble codes.
One way to get around this fail to reset would be to install a double conversion UPS on the supply side. This would ensure that the controller would never see an outage and the incoming voltage would be as regulated and pure as you could get. That is, assuming there is enough battery capacity to keep things alive for a reasonable length of time.
Another work around I am considering would be to just remove PF and PF1 and just jumper the N.O. contacts. There would be no emergency lowering with the existing little UPS of course, but it doesn't work anyway. With the jumpers in place everything should come back to life on restoration of power, unless there is something else wrong with the board.
Anyway, these are my thoughts at present.
