MEP-804B Governor control issue

[jbcirs]

I have a MEP-804B generator with the control for the frequency will randomly switch between the governor computer and manual control knob. I can adjust the fine tuning, but it’s different tunings for both. Seems like it’s worse when the weather is in the extremes.

What do I need to do to trouble shoot this issue? Could it be a wiring or ground issue? Is the governor computer faulty? If so what part do I need to replace? Is there a way to make it manually only?

 

[Guyfang]

What do you mean by switch? The hand control should not be used at all. Whats different tuning? Whats a govenor computer? Look at the book, so you can use the right names for things, and we dont get mixed up. Or pictures.

 

[jbcirs]

Randomly, the computer will control the frequency, prompting me to make fine-tuning adjustments using a small screw on the Woodward. When the computer does not take control, I have to readjust the screw, allowing me to manually set it to 60Hz using the front knob.

Video link of me using the knob to manual adjust the frequency (which I don't think is suppose to be used).

I have it currently adjusted for the computer control, but right now its not working.

I have no lights on showing an issue and it will take a load.

This is the small screw I adjust for fine tuning the computer controlled frequency or to be able to change the manual knob on the outside to be able to tune the frequency to 60htz.


This is the frequency knob.

 

[Guyfang]

Randomly, the computer will control the frequency, prompting me to make fine-tuning adjustments using a small screw on the Woodward. When the computer does not take control, I have to readjust the screw, allowing me to manually set it to 60Hz using the front knob.
There is no computer in this set. What are you calling a computer? All components have the designated ID printed next to them. Are you calling the A5, (Speed control), the computer? The only way to adjust the Speed, (Hertz) is with the knob on the control panel. You are not supposed to adjust anything on the A5. Once the A5 is propperly adjusted, it is NOT to be fooled with.

Are you holding the S1, ( start switch) up long enough? If you let the S1 go too soon, the A5 may not take control of engine speed. Did you conferm all the voltages on the A5 adjustment sheet I sent you?

 

[jbcirs]

Randomly, the computer will control the frequency, prompting me to make fine-tuning adjustments using a small screw on the Woodward. When the computer does not take control, I have to readjust the screw, allowing me to manually set it to 60Hz using the front knob.
There is no computer in this set. What are you calling a computer? All components have the designated ID printed next to them. Are you calling the A5, (Speed control), the computer? The only way to adjust the Speed, (Hertz) is with the knob on the control panel. You are not supposed to adjust anything on the A5. Once the A5 is propperly adjusted, it is NOT to be fooled with.

Are you holding the S1, ( start switch) up long enough? If you let the S1 go too soon, the A5 may not take control of engine speed. Did you conferm all the voltages on the A5 adjustment sheet I sent you?

Randomly, the computer will control the frequency, prompting me to make fine-tuning adjustments using a small screw on the Woodward. When the computer does not take control, I have to readjust the screw, allowing me to manually set it to 60Hz using the front knob.
There is no computer in this set. What are you calling a computer? All components have the designated ID printed next to them. Are you calling the A5, (Speed control), the computer? The only way to adjust the Speed, (Hertz) is with the knob on the control panel. You are not supposed to adjust anything on the A5. Once the A5 is propperly adjusted, it is NOT to be fooled with.

Are you holding the S1, ( start switch) up long enough? If you let the S1 go too soon, the A5 may not take control of engine speed. Did you conferm all the voltages on the A5 adjustment sheet I sent you?

I didn’t receive any sheets. Also do you have a link to documents, this way I can reply properly.

 

[Guyfang]

Link to TM's

All the TM' you need for the MEP-804B

This should be all the TM's you need to work on the MEP-804B gen set. Basically, its the same books as the MEP-804A, with the addition of TM 9-2815-538-24&P, the new engine book.

www.steelsoldiers.com

Attached is A5 Adjustment procedure.

 

[jbcirs]

Link to TM's

All the TM' you need for the MEP-804B

This should be all the TM's you need to work on the MEP-804B gen set. Basically, its the same books as the MEP-804A, with the addition of TM 9-2815-538-24&P, the new engine book.

www.steelsoldiers.com

Attached is A5 Adjustment procedure.

I get ~5.514 v DC on 9 and 10 of the A5 . On 16 and 17 ~5.120 v AC.

 

[Guyfang]

You need to readjust the MPU. I would pull it out, clean it and reinstall it. Then readjust it to as close to 3 volts as you can.

 

[jbcirs]

You need to readjust the MPU. I would pull it out, clean it and reinstall it. Then readjust it to as close to 3 volts as you can.

I cleaned it, and was having trouble adjusting it, when the end of it was chopped off. Where can I buy another MPU?

Will something like this work from Amazon?

Amazon.com

 

[Guyfang]

I dont know. There are several different sizes. In the norm, if it fits in the hole, it should work.
I know that NSN: 6695-01-367-9723, part # 88-21061
or
NSN: 2815-01-499-1057, part # 96-23734 or MSP6735 Will fit.

Mostly I tell people to take the bad one to a Truck repair shop, and tell them you want one just like it. Should be cheaper then anything you find on line. One of the guys got one for 35 bucks, at a truck stop repair shop. Some places cost more. But when you look in the net and see what Green Mountain wants, you will start to look around different.

When you screw in the new one, screw it in, by hand, till it hits bottom. Turn it back 3/4 turn. Hand tighten the lock nut. Then have someone use the S10 Dead crank switch to turn over the engine. You measure for AC VOLTS, on the two wires. You want 3 VAC, MAX. No more. Get as close to 3 VAC as possible. 2.8 is good enough. But the set LIKES 3 VAC. Then lock the nut down, without changing the MPU. You are done. Hook up the wires.

 

[jbcirs]

I dont know. There are several different sizes. In the norm, if it fits in the hole, it should work.
I know that NSN: 6695-01-367-9723, part # 88-21061
or
NSN: 2815-01-499-1057, part # 96-23734 or MSP6735 Will fit.

Mostly I tell people to take the bad one to a Truck repair shop, and tell them you want one just like it. Should be cheaper then anything you find on line. One of the guys got one for 35 bucks, at a truck stop repair shop. Some places cost more. But when you look in the net and see what Green Mountain wants, you will start to look around different.

When you screw in the new one, screw it in, by hand, till it hits bottom. Turn it back 3/4 turn. Hand tighten the lock nut. Then have someone use the S10 Dead crank switch to turn over the engine. You measure for AC VOLTS, on the two wires. You want 3 VAC, MAX. No more. Get as close to 3 VAC as possible. 2.8 is good enough. But the set LIKES 3 VAC. Then lock the nut down, without changing the MPU. You are done. Hook up the wires.

I was able to get one on Amazon MSP6729. I had to turn it about 1/4 a turn outward to get around 2.79v. 3/4 of a turn gets me ~0.6v. I can't get it much higher as it will be to close. I haven't seen any changes on the A5. I still have control of the R2. What should I do next?

I get 303.6 ohm's when measuring 148C and 147C. Do I need to fix this? How to fix this?

 

[Guyfang]

I get 303.6 ohm's when measuring 148C and 147C. Do I need to fix this? How to fix this?
This is too low a reading. Did you check it first at the MPU, (wires unhooked?) and then at the A5, (Wires unhooked?)

I was able to get one on Amazon MSP6729

The part number I posted was MSP6735. I hope its compatable between them.

 

[jbcirs]

I get 303.6 ohm's when measuring 148C and 147C. Do I need to fix this? How to fix this?
This is too low a reading. Did you check it first at the MPU, (wires unhooked?) and then at the A5, (Wires unhooked?)

I was able to get one on Amazon MSP6729

The part number I posted was MSP6735. I hope its compatable between them.

I have the same ohm’s at the MPU as I have at 148C and 147C. Wires unhooked on both tests. What should I do next?

 

[Guyfang]

Says here, Ohms should be between 900-1200 ohms. Lower resistance indicates a problem in the mag pickup. Did a spec sheet come with your MPU?

 

[jbcirs]

View attachment 905059

Says here, Ohms should be between 900-1200 ohms. Lower resistance indicates a problem in the mag pickup. Did a spec sheet come with your MPU?

I don't have a spec for it. To eliminate this problem, I ordered the exact part from Green Mountain Generators. Once it arrives I will install it and report back.

 

[jbcirs]

View attachment 905059

Says here, Ohms should be between 900-1200 ohms. Lower resistance indicates a problem in the mag pickup. Did a spec sheet come with your MPU?

I have installed the new MPU from Green Mountain Generators . On the MPU I'm getting 2.813V AC and 972 ohms (test the part before install and at the A5). I still have the same issue.

I did get the issues to reproduce for a short time as seen in the two videos. The first one show where the R2 can adjust the frequency and at the end the A5 takes control. The second one is when the A5 controls the frequency and the R2 is not useable. The only things that have changed is it was in the 80's outside, I had recently recharged the batteries with a battery charger, and A5 stopped control when I put one lead from the multimeter on 150A screw. I did remove that connection and check it, I didn't see any issue. What should I try next?

 

[kloppk]

I see the output voltage on the meter jittering and all over the place at times when the voltage and frequency goes whacky.
There may be a AC Voltage Regulator issue.

 

[jbcirs]

I see the output voltage on the meter jittering and all over the place at times when the frequency goes whacky.
There may be a AC Voltage Regulator issue.

When the A5 takes control I have seen it do that before. To me it acts like it is starting and adjusting to its own settings. The voltage is normally very stable accept when it’s switching control.

I expect the frequency to go high when I have the frequency set for using R2 (which I should not be able to use). Based on what I seen on this generator before. I have to adjust the tuning for the frequency by using the set screw on the A5 when it switches.

Thoughts? How do I test the AC regulator? Anything else should I test too?

 

[kloppk]

The test for the AC VR is in the -24 TM

 

[Guyfang]

Thats a real possibility. The A5 works. It holds steady frequency. Just before things go south, I hear strange noises. Where are they coming from, and why are you moving the AM-VM switch all the time?