MEP-806A Low voltage/ low frequency problem ??

[R Racing]

Got my MEP-806a started today. Engine runs great !! But have a under voltage light. Frequency wont go above 51.5 hertz and the 110 outlet puts out 22 VAC ? I have been reading the TMS for over 4 hrs and checked a few things. The big issue I see in the TMs is they cover either or problems but not both tied together ? Tried the 50 hz /60hz switch. It works but on 50 Hz The voltage and hZ drop way down. On 60 Hz the engine sounds like its doing in the plus 2000 rpm. If you you turn the frequency pot. The RPM does increase and decrease , But the frequency moves like 1 HZ ? if you pull on the throttle just a bit on the pump . The engine goes into overspeed. I looked for broken wires and looked at the frequency transducer . Everything looks ok. anyone have any clues at all ?

 

[dmetalmiki]

That could be a faulty gen set, Ours did that, but when we incresed the RPMs the voltage went up correspondingly. On the Onans the RPMs dictate Voltage available. Wish I could help more. Perhaps get an electrician to check the windings?.

 

[R Racing]

Does anyone know anything about the Woodward control box in these units ? Noticed some frequency and over speed adjustments on it. The voltage at the meter on the control panel is reading 87 volts from L1 to neutral .

 

[DieselAddict]

Do you have the TM? The troubleshooting section for the governor starts on page 227. Give this a look and see if it helps. I'm going to look up the module number and see if its like the ones I've worked on before.

http://greenmountaingenerators.com/...ical-Manual-Repair-Parts-TM-9-6115-645-24.pdf

 

[R Racing]

Thank you ! ! Everything I have been taught is the frequency is rpm. Even though the engine sounds like it is screaming. I have no way to check rpm. I'm wondering if that unit is miss adjusted . Or bad. I have seen alot of them removed on gens being sold.

 

[R Racing]

Also I went over all of the wiring and only found 1 issue even though it really shouldn't be a issue. The GND wire to the output board was rubbed threw it's shield against the gen housing. Being that's grounded as well it shouldn't have caused any issues.

 

[DieselAddict]

If you have a HZ reading on your Voltmeter you can check the frequency. HZ is RPM on these generators but when they are run too slow they can't generate enough current on the exciter.

The bonding jumper wont be the source of this problem.

First check your RPM if you can and then lets figure out why it won't make voltage.

 

[R Racing]

Maybe you might know. The blue box (Woodard unit should have a input for rpm. I noticed a pickup sensor on the bell housing)

 

[R Racing]

Unfortunately my meter is a cheapy rat shack it . It just does ohms. AC. DC . It's about as basic as they get

 

[DieselAddict]

On page 141 of the TM is the pinout of the diagnostic connector. I think most of what you'll need to test is there. I'm looking in the manual now to see the first thing to test.

Lets see if we can get you a RPM test doable with what you have.

 

[DieselAddict]

Maybe you might know. The blue box (Woodard unit should have a input for rpm. I noticed a pickup sensor on the bell housing)

The magnet pickup does go to the governor module. According to the electrical drawing its on terminals (16) and (17).

 

[R Racing]

The magnet pickup does go to the governor module. According to the electrical drawing its on terminals (16) and (17).

Is it a digital input ? Wasn't sure if it is a D/A setup ?

 

[DieselAddict]

It will be a digital pulse train.

 

[R Racing]

Also on page 230 it shows the pump adjustment on the low speed idle. Mine had been backed out shout 2 1/2 turns. I adjusted it but it only increased the frequency by about 1 hz When it was back where it was.

 

[DieselAddict]

I highly recommend getting a meter with a frequency readout. There are a number of measurements that will require it. You shouldn't trust the HZ readout until we know what is going on with the governor.

One reading you can take with a normal voltmeter is the exciter voltage. Those are terminals (F) and (J) in the diagnostic plug. According to the manual you'll see a DC voltage between those when the engine is running.

 

[R Racing]

I highly recommend getting a meter with a frequency readout. There are a number of measurements that will require it. You shouldn't trust the HZ readout until we know what is going on with the governor.

One reading you can take with a normal voltmeter is the exciter voltage. Those are terminals (F) and (J) in the diagnostic plug. According to the manual you'll see a DC voltage between those when the engine is running.

OK I'll check that tomorrow. I use to have a fluke model 97. But someone I guess liked it more and it grew feet

 

[1800 Diesel]

OK I'll check that tomorrow. I use to have a fluke model 97. But someone I guess liked it more and it grew feet

I couldn't afford a Fluke. Bought an Extech that has freq capability & it's accurate. Also bought a tachometer that has direct contact method or remote with the reflective tape.

 

[DieselAddict]

I couldn't afford a Fluke. Bought an Extech that has freq capability & it's accurate. Also bought a tachometer that has direct contact method or remote with the reflective tape.

+1. There are some reasonable options for a full featured instrument that won't kill your wallet.

 

[R Racing]

Bought a tach last night. It should be here before weeks end I hope. A friend is swinging by tonight with his fluke so I'm hoping we get somewhere . I'll look in to extech in the meantime.

 

[R Racing]

OK Boys and Girls !! I got this figured out ! Ok a old friend came over with a tach to see what the engine is doing. We put the tape on the balancer. fire it up and it was running 1550 to 1625 RPM . Still have low frequency and voltage. I went to go get a small screw driver and just before I was going to adjust the frequency the engine stumbled twice then the rpm jumped up to 1800 RPM by itself . Oddly for a moment the frequency and voltage were still low . Then the generator did a self flash ! and boom everything was reading correctly !! so after turning it back off then back on. it runs for a min then it self flashes itself . So for it to do this the RPM needs to be at 1800 . So that's why it wouldn't work before. Even doing it manually flash before it wouldn't because the RPM were to low.