MEP-006A- low voltage

[electricdiesel]

Hi,

New member here. What a wonderful site. I just got my hands on a MEP-006A Fremont 1974 last month with the Allis Chalmers turbo diesel engine. It has a little under 6000 hours. I've read the half dozen MEP 006A threads from other members on here and I'm having similar problems. Grateful for those posts and answers/help so far. I also watched some Matt Verley videos which gave me some more insight on potential user issues on the MEPs. I have also printed and read both TM 12 and 34 which were helpful, but I'm still stuck.

I got the genset and installed (2) 845cca marine batteries, poured the recommended quarts of coolant in it, put some #2 diesel fuel in her and it started! However, I tried plugging an impact driver in the 120V convenience receptacle to test for power and it doesn't turn on.

I held the s2/start switch for 15 seconds to get help the magnetic field started (source: Matt Verley), but the Volt meter just stays at 240V until I let go of the start switch and let it go back to run mode and then thr Voltmeters goes down to about 50V. The Hertz cycle meter stay at 48 or 0. I can't differentiate between what the true reading is. There is oil pressure and the battery ammeter is in the green. See attached picture.

I checked the exciter assembly box (lots of dirt in it) and checked the back of the Voltage Regulator card and there's no burnt leads/soldering lines on the card. See attached pictures.

I saw an exciter assembly box online (since it sounds lioe the Voltage Regulator and card often quit), but I wanted to see what other remedys I could perform on it to get the 3 phase power it was designed to produce.

Any help and guidance would be greatly appreciated.

 

[Scoobyshep]

I had a similar issue with my 004. Long story short there was a burnt trace on the A5 card. It was off of the relay. Once I repaired the card it worked great. Another thing to look at is the speed switch.

Sent from my SM-G950U using Tapatalk

 

[Guyfang]

You are getting initial excitation. That's what happens when you hold S2 in the start position. When the S2 is released, the voltage falls of. Yes, you could look at the back of A5, but that's a long shot. The A9 speed switch works, proven by the fact you are getting initial excitation. The volt reg card will not always show a burn mark on the backside.

The way this set works is so. The initial excitation comes from the S2, through the S9 and when the main gen lights off, The static exciter/volt reg sense 120 volts, and assume control of the production/excitation function. How fit are you at electronics? The Static exciter is testable and repairable.

 

[Guyfang]

After looking again at your pictures, I saw the volt reg card laying on the mounting brackit. Did you remove the mounting screws? There are 4 mounting screws, and 4 plastic standoffs. Without the standoffs, the card will short to ground.

 

[electricdiesel]

You are getting initial excitation. That's what happens when you hold S2 in the start position. When the S2 is released, the voltage falls of. Yes, you could look at the back of A5, but that's a long shot. The A9 speed switch works, proven by the fact you are getting initial excitation. The volt reg card will not always show a burn mark on the backside.

The way this set works is so. The initial excitation comes from the S2, through the S9 and when the main gen lights off, The static exciter/volt reg sense 120 volts, and assume control of the production/excitation function. How fit are you at electronics? The Static exciter is testable and repairable.

I'm not super savvy with electronics, but I can test for basic continuty, voltage using a digital multimeter and maybe solder a bit. I don't know how to use or fix an oscilloscope, resistor, capacitor, and other components.

However, I'd like to give it a shot if there was some guidance. I'm not at the generator right now, but I can get my hands on it this Wednesday. I'll unhook the wires from the static excitor/voltage card when I get to the genset. What would be required to test and potentially repair it?

 

[Guyfang]

I would suggest downloading the -34 TM and reading the test procedures. Some are easy, just a Meter. Some require more. Peapvp, a member here of SS, has been involved in several threads that were more or less involved with testing and repairing the static excitor. Might pay to look them up.

 

[electricdiesel]

Hi again,

So here's an update. I had the generator fall forward on the pintle hook since I forgot to connect the support bracket to the hydraulic kickstand. It was a huge mess with oil and diesel all over. It didn't start so I filled up the oil again and then the batteries were dead so I had to replace them as well. Now, the generator starts again!

However, I'm still getting only 50V when it's running. I've extracted the VR(Voltage Regulator) out so how should I test to see if it's working properly? I cleaned it up so it's easier to see the connections and components on the board. Please see pictures attached for what the VR looks like right now.

 

[Guyfang]

Open up the -34 manual. Read the test procedure, and decide if you have the gear you need to do the job.

 

[electricdiesel]

Open up the -34 manual. Read the test procedure, and decide if you have the gear you need to do the job.

Hi Guy!

Thank you for your guidance. So, I kept calling the Voltage Regulator Printed Circuit Board the VR by mistake. I pulled out the VR, but the schematics/instructions are a bit off on the TM-34. It mentions a yellow lead and there are two resistors and they are both red (no colored circular markings on the larger resistors to denote resistance values). Anywho, I scored a military weller soldering kit on an auction since I need to remove the two resistors and test them individually so have to wait a few days for that! Excited to get more in depth on this fantastic machine!

 

[Guyfang]

The resistence values are in the TM' as soon as I can get to my computer I will look them up.

 

[electricdiesel]

The resistence values are in the TM' as soon as I can get to my computer I will look them up.

TM-34 says 600-900 Ohms. I unscrewed them, but I don't think I'll get a proper reading until I solder them off and test them individually.

 

[Guyfang]

Roger. At least one side of the component needs to be un soldered.

 

[electricdiesel]

Roger. At least one side of the component needs to be un soldered.

The soldering kit came in the mail. It's an interesting design to use a screw as a part of the resistor. Before I begin desoldering and testing the resistors, does anything look wrong with this resistor?

 

[Guyfang]

No, I don't see anything wrong. Having said that. I have more then a few times checked ceramic resisters, and they looked great. But would not ohm out.

Remember, troubleshooting is like doing a puzzle. Once you have checked something out, its like a piece you fit to your puzzle. Its done, you do not have to worry about it again. Sooner or later, your puzzle is done.