metalchips
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- Millersville, MD
Hello all, I've lurked in the past but this is my first post.
I have a MEP-806a that I use to power my machine shop. I have had it since 2013 and put 12,000 hours on it. I've done every repair imaginable to this machine but I currently have a problem I have not been able to solve.
Currently I have no frequency and no voltage. The engine runs great, but I can't get anything from the genset. I have about 40 hours into troubleshooting this and I basically gave up, which is not my style. Here's how to failure / my troubleshooting went:
The first thing to fail was upon start the machine would over-rev and shut down with an over-voltage light when I released the start switch. If I kept it in field flash / starting mode the engine ran properly. I remembered seeing the Hz read out OK during this time but I don't remember the voltage. I suspected a bad governor solenoid so I replaced with a spare and no change.
Next I followed the instructions in the TM to disable the voltage regulator. My thought process was stop the over voltage condition so that I could troubleshoot. With the voltage regulator disconnected the engine stopped over-revving and would run at 60Hz with no voltage. I talked to the eBay seller who sells the voltage regulator kits and he wanted me to seriously check connections so I took 2 days and I did exactly that.
One of the terminals on the re connectable terminal board, I think #7, was loose. This terminal connects a single phase to the control transformer for the voltage regulator, so I thought that could be it. No luck. I found a couple not-so-tight connections on the terminal strips on the bottom of the control box. No luck. Next I removed the control transformer, the droop transformer, and the current transformer and inspected and tested each one. Everything tested OK. I tested the potentiometer for the voltage and frequency. They are good.
At some point during all of this the engine stopped over-revving and the machine stopped making frequency and voltage completely. So, the problem moving forward is: engine runs fine, no frequency, and no voltage.
The next thing I did was continue looking for loose wires. I found a few but looking at the wiring diagrams there's no way these wires had anything to do with the problem. I continued to test the voltage regulator following the TM and I thought it could be bad so I went ahead and bought one. When it came in I replaced it and nothing changed. I got deeper into the TM and the wiring diagram and I chased every wire that has anything to do with the field flash function and the voltage regulator. The diodes in the control box are all good. The resistors in the control box are all good. All of the relays on the back panel are good. The over/under voltage relay is working. 24v from the alternator is perfect. When I hold the start switch down 24v is sent to the exciter every time.
Next I needed to test the genset itself, so I pulled all the leads and removed the end of the genset. I removed the ring of diodes from the exciter and tested them. 2 of the diodes were bad. I replaced them. I did all the tests I could to the genset and everything seemed OK. I don't have a load bank, so I couldn't run any tests that required one. I replaced the bearing that holds the rotor shaft and put it all back together. No change!
Next I re-tested the voltage regulator, the governor, the voltmeter, the frequency meter, the over/under voltage light, the starting switch, the starting relay, the diodes and the resistors. I removed the magnetic pickup sensor and cleaned and tested it. I have it calibrated to pulse 3 volts.
Right now:
Engine runs great
Frequency dial WORKS and adjusts engine RPM
Frequency meter shows nothing
Voltmeter shows nothing
Voltage dial does nothing
Undervoltage light
Does anyone have any ideas?
Since I use this to power my machine shop I rented a generator. I put at least 40 hours into troubleshooting this but I had to stop and get back to normal workflow. The rental generator costs $2000/month so I need to figure out whats going on with this soon. I think that my genset is dead. Unfortunately I can't find any on eBay right now.
Thanks for any advice,
Evan
I have a MEP-806a that I use to power my machine shop. I have had it since 2013 and put 12,000 hours on it. I've done every repair imaginable to this machine but I currently have a problem I have not been able to solve.
Currently I have no frequency and no voltage. The engine runs great, but I can't get anything from the genset. I have about 40 hours into troubleshooting this and I basically gave up, which is not my style. Here's how to failure / my troubleshooting went:
The first thing to fail was upon start the machine would over-rev and shut down with an over-voltage light when I released the start switch. If I kept it in field flash / starting mode the engine ran properly. I remembered seeing the Hz read out OK during this time but I don't remember the voltage. I suspected a bad governor solenoid so I replaced with a spare and no change.
Next I followed the instructions in the TM to disable the voltage regulator. My thought process was stop the over voltage condition so that I could troubleshoot. With the voltage regulator disconnected the engine stopped over-revving and would run at 60Hz with no voltage. I talked to the eBay seller who sells the voltage regulator kits and he wanted me to seriously check connections so I took 2 days and I did exactly that.
One of the terminals on the re connectable terminal board, I think #7, was loose. This terminal connects a single phase to the control transformer for the voltage regulator, so I thought that could be it. No luck. I found a couple not-so-tight connections on the terminal strips on the bottom of the control box. No luck. Next I removed the control transformer, the droop transformer, and the current transformer and inspected and tested each one. Everything tested OK. I tested the potentiometer for the voltage and frequency. They are good.
At some point during all of this the engine stopped over-revving and the machine stopped making frequency and voltage completely. So, the problem moving forward is: engine runs fine, no frequency, and no voltage.
The next thing I did was continue looking for loose wires. I found a few but looking at the wiring diagrams there's no way these wires had anything to do with the problem. I continued to test the voltage regulator following the TM and I thought it could be bad so I went ahead and bought one. When it came in I replaced it and nothing changed. I got deeper into the TM and the wiring diagram and I chased every wire that has anything to do with the field flash function and the voltage regulator. The diodes in the control box are all good. The resistors in the control box are all good. All of the relays on the back panel are good. The over/under voltage relay is working. 24v from the alternator is perfect. When I hold the start switch down 24v is sent to the exciter every time.
Next I needed to test the genset itself, so I pulled all the leads and removed the end of the genset. I removed the ring of diodes from the exciter and tested them. 2 of the diodes were bad. I replaced them. I did all the tests I could to the genset and everything seemed OK. I don't have a load bank, so I couldn't run any tests that required one. I replaced the bearing that holds the rotor shaft and put it all back together. No change!
Next I re-tested the voltage regulator, the governor, the voltmeter, the frequency meter, the over/under voltage light, the starting switch, the starting relay, the diodes and the resistors. I removed the magnetic pickup sensor and cleaned and tested it. I have it calibrated to pulse 3 volts.
Right now:
Engine runs great
Frequency dial WORKS and adjusts engine RPM
Frequency meter shows nothing
Voltmeter shows nothing
Voltage dial does nothing
Undervoltage light
Does anyone have any ideas?
Since I use this to power my machine shop I rented a generator. I put at least 40 hours into troubleshooting this but I had to stop and get back to normal workflow. The rental generator costs $2000/month so I need to figure out whats going on with this soon. I think that my genset is dead. Unfortunately I can't find any on eBay right now.
Thanks for any advice,
Evan