Home Forums General Discussion Technical Questions Strange Epoch II Problem

A fellow mechanic is fighting a loosing battle on an Epoch II geared Freight car. The MPT PCB is re-booting several times a day so the car will think it's lost. It takes a hand/auto reset to get it back going. Here's what has been done:
All new PCBs in the controller (several have been changed more than once).
All new power supplies.
New traveling cable.
New TCP (several).
New FCBs.

He's monitored the main line voltage + had a scope on it. He's min-maxed all the power supply voltages for days - no adverse readings. Checked all diodes in the controller. Checked the zener diodes in the car station. The only "thing" he knows for sure is that the MPT PCB is dropping the output to the power relay when it resets.

e-man, I had this exact problem a year ago or so, and it was a freight car, your friend wouldnt happen to be in the LA area near the airport would he? any way, the problem turned out to be a power supply, if memory serves me, there was something about this job with the power supply to the mpt board that was not on the print that we had. I believe there was another supply feeding the mpt power supply input, even though the voltages were exact it still caused the problem you are describing. have your friend trace the power supply input wires to the mpt, to make sure they go to the power supply he has replaced. then trace the wiring from that supply back to see if it matches the print.

Thanks Scott,

No, we're over here on the east coast. I've been up there with him and he's changed all of the power supplies in the controller. I don't think he's actually pulled on the wires, that's worth trying.

if all the power supplies have been changed, then it probably a stretch, but better then no idea at all, maybe some wiring is loose. I was thinking about this today, Is he sure the mpt is rebooting, or is the dpower output that picks the PWR relay just dropping out? I dont work on these very often, but i believe that when the one i was working on failed, it would reboot the mpt and go back into service with no other interaction from us. if the mpt is actually rebooting, then it has to be something with the power supply, did he replace the power supply feeding mpt with a unit that has the same amperage rating? I have seen power supplies that have been replaced with lower amp rating that could not handle the load and be on the hairy edge which could cause trouble. any way something to think about. tell your buddy good luck, i feel for him, i have been on a couple of these jobs for more then a few days at a time, what a pain.

Are the power supplies getting replaced like for like?
The oem ones I think are 28 amps
The cheap replacements come at like 7 or 8 amps
We found this too be a problem when a car would go down and switch dispatching roles .The car with generic power supply would reset similar to your issue. The current output just wasn't enough to handle the load . Is the car using fiber optics on the pulse wheel ?

Good post fate, this has happened to me on other controllers, where the power supply voltage is ok but the current rating was not enough and would cause still further problems. this is a good thing to remember on all elevator controllers, just because it says 24 volt output etc. does not mean it can handle the load all the time. when changing power supplies make sure the amp rating is the same or higher.

MPT board monitors two separate 5v supplies (and 24v as well) . Check them at the board, not at the power supply. Set to 5.05 at board. Check the first one at TP1 and TP2 , and check the second one across the red varistor located near the top right corner of MPT board. Second one comes in via ribbon cable , so there is no other test point at the board. Also keep in mind voltage monitoring circuit sometimes goes bad on board itself resulting in unjustified shutdowns of microprocessor.

Yes, it's using fiber optics on the pulse wheel. He replaced the fiber and the heads not all that long ago for a different problem.

All voltages were checked at the board and set with Fluke 87s, I'm not sure of the exact voltage he set it at, but he had a very seasoned Westinghouse Adjuster spend about 3 days on it up there with him and they replaced all the boards again. It's been running (we think), For some reason I think it's a wiring and/or connection problem.