I recently got interested in military generators and came across a 2004 802a. I bought it and it needed a oil filter and batteries. I replaced the filter and installed new batteries and had no power and no response from the dead crank switch. I found out I had the front and back backwards on the install diagram and got the batteries installed the way they needed to be. I then found the FU1 fuse blown and replaced it. Still no response from the control panel other than the voltmeter pegged negative. I did some testing and ended up cutting the CR1 diode out and jumped in a new one. Still no response from the dead crank or main switch. I then checked and verified voltage was 24+. Got 24v on either side of CR1. 24 on either side of the MT4. I then noticed the MT4 metal strip was blown. I jumped it and boom I had power. I had to replace the fuel pump, and it ran great. Power output was good, and all was well until I went to solder the new diode in. After soldering it in, I lost all dc power. I know I need to find a new shunt at the least, but I have no idea what I did wrong. I have 24v at the starter, 24v on either side of MT4 and the diode. I weirdly have 17v on some spots of the main switch and on the dead crank wires. I have nothing on either side of the e stop, fuse, and breaker. Any help would be sure appreciated!
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Fermont MEP DC control power issues
- Thread starter Ramnation
- Start date
- 1,154
- 1,329
- 113
- Location
- Basehor, KS
From what you are describing, it sounds like a cold solder connection on the Terminal Post of the Cathode side of Diode CR 1.
The wire goes from this Terminal post to S10 TB 2 ( COM )
The wire goes from this Terminal post to S10 TB 2 ( COM )
- 17,373
- 25,681
- 113
- Location
- Burgkunstadt, Germany
Or you have the diode in backwards.
- 2,778
- 6,628
- 113
- Location
- West greenwich/RI
I previously thought the same thing, but after rereading he says he has 24V on both sides of the diode, so I assumed it must be correct, right?
- 2,778
- 6,628
- 113
- Location
- West greenwich/RI
Looking at the schematic the cold solder joint theory is looking more and more promising.
Try sticking your jumper across the CR1 posts again and see if it comes back to life.
Follow the red line from the alternator to MT4 to CR1 then to the dead crank, then to the E-stop and CB1 and lastly S1
Low voltage at the dead crank would support the cold solder theory or something wrong with the diode. Did you use the correct replacement diode?
Try sticking your jumper across the CR1 posts again and see if it comes back to life.
Follow the red line from the alternator to MT4 to CR1 then to the dead crank, then to the E-stop and CB1 and lastly S1
Low voltage at the dead crank would support the cold solder theory or something wrong with the diode. Did you use the correct replacement diode?
- 17,373
- 25,681
- 113
- Location
- Burgkunstadt, Germany
Yeah, it sounds more like a cold solder now. A cold solder can show you the right volts. But will not pass amps.