TAC32 blowing fuse P24M

Good morning brothers & sisters,

I have a tac32 that went down Wednesday morning EST and I've been troubleshooting since then.

It is a 4-stop hydro single-post with a main & aux COP. The first shutdown had a passenger going up to the top landing but stopped cartop level with the top floor. I found that the P24M 2amp pico fuse on the CWIL had blown. I replaced it & ran it ti the top again until it shutdown cartop level with top landing. Replaced, reset, ran it up from the bottom on machine room inspection until it blew again cartop level with the 3rd landing.

I know this fuse feeds 24vdc spare connectors, door operation, battery charger, and selector. I've removed the door from the circuit and it still blew after a normal travel. I've removed the gong, battery charger, and selector: it still blows typically during travel.

It seems to shutdown near the same area now (between 3 & 4) going up or down, but more frequently now going down; whereas, it would shutdown going up. The travel cable looks fine, there are no shorts on the CWIL, door board, selector, charger, and all cables in between appear to be fine. I've unplugged all connections and methodically plugged each one back in with a 30sec wait in between plugging in. Still blows during travel.

I've attached the area of the print with the fuse in question.
Any suggestions? Any and all help is greatly appreciated.

Work safe!

J. Clark

Almost has to be in the travel cord. After the fuse has blown, have you checked the circuits for ground before moving the car?

Yes, i read from both side of where that fuse is with and without fuse in. Left side OL right side 1.5kOhm. A couple of other guys said it sounds like a travel cable, but wouldn't that blow the fuse on the power supply in the COP first?

As much as I agree that it sounds like a travel cable, I don’t see that P24M going through the traveler at all. Have you tried running with the buzzer unplugged, con 605? That’s just a guess based on what you said about it blowing at floor level. From a quick survey of the CWIL I had in the van, this is what I see on that circuit:

Con 650 - bottom left used for on board I/O, never seen it used.
Con 654 - car light/fan relay
Con 605 - buzzer
Con 300 - car top inspection switch
Con 303 - HW access switch
Con 210A - front door operator
Con 220A - rear door operator
Cons 652 & 653 - SPI loop to S24 cards
Cons 606 & 656 - front lanterns
Cons 607 & 657 - rear lanterns
Con 651 - position indicator
Con 706 - selector

If it's wired correctly it is in the main COP. Have you tried to eliminate the whole main COP and run off only the auxiliary COP yet? i had an issue once with my door edge cable, very intermittent and the power comes from the P24M. Try isolating them and run at full speed.

Can you sub-fuse inside the main COP? Isolate which part of the P24M is blowing. Do you have hardware cloth in the hoistway to keep the travel cable from hitting the spreaders or brackets? Had one that would pierce the travel cable jacket and then pull out as the car stopped eliminating the short, but I agree that it doesnt seem to be travel cable related. Will it blow on independent service? That would eliminate the lanterns. Disconnect the PIs to eliminate them?

You could break up the circuit with in-line fuses but it would be a big PIA. Maybe if you had a couple RJ45 breakout boards or couplers. And you could probably make some type of breakout adapters for the MTA plugs because you would not want to cut any factory wiring for temporary troubleshooting.

But you said it still blew on MR inspection so I think you should be able to run like that with every plug I listed removed except the selector if you jump con 300 pins 1-2 for INCTM and con 303 pins 1-3 for INHAM.

P24m is being fed from the cop power supply so i doubt its a traveler issue. I would start with replacing the cwil board but thats just me. Also does it blow the fuse with the cop’s open?

BTW, I have now seen Con 650 used but don’t have a print that shows it.

Omg did you fix it? I’m having same issue. Blew twice in two days same place just before top term. After changing tape guides it’s not canceling/ false firing car calls, won’t go on ind ser,etc. Seems like it’s stepping fine with P.I. I am gonna replace cwil tommorow any suggestions? Thanks