MEP-803a - Field Flash Grinding Noise

[hcso2332]

Has anyone had an issue with a grinding type noise with field flashing either an 802a/803a?

I am working on a 803 that has no voltage or hertz.

When I hold the start to flash I get a grinding type noise. On the S1 #7 I get 24v for a blip and nothing happens. Also, using a good field flash relay from a working set.

I am using a good working VR1 from a working unit and went through the test procedures and don't get any voltage when performing procedures H & J.

I also tested the speed sensor and get no voltage during start up. This 803 does not have the quad mod and has 31 hours the meter. I took the cover off the the back of the generator head and saw nothing exciting on the exciter section. Everything is real clean. I started the TM procedures for testing the exciter but the CR connectors are a bear to get to.

I have spent quite a few hours going through the TM and trying to figure it out but I am at a loss right now.

 

[Guyfang]

Did you pull the Mag Pickup out?

 

[hcso2332]

I removed the mag pick-up - it had quite a few metal shaving on it. I removed the shavings and reinstalled it. Good news is the grinding went away but still no power. I am getting 3.3 volts on the lugs and on the convenience outlet.

 

[Guyfang]

The grinding was the mag pickup.

now, disconnect the two leads to the mag pickup. Set the multimeter to AC voltage. Mesure at the two leads that go to the mag pickup. Have someone turn the engine over with the S1 or S10. What voltage reading do you get?

 

[hcso2332]

The grinding was the mag pickup.

now, disconnect the two leads to the mag pickup. Set the multimeter to AC voltage. Mesure at the two leads that go to the mag pickup. Have someone turn the engine over with the S1 or S10. What voltage reading do you get?

0 volts at the mag pick-up

 

[Guyfang]

If you are getting 0, (zero) volts AC from the mag pickup, while the engine is cranking over, the mag pickup is bad, or mal adjusted. I assume you read the procedure in the TM for testing and replacement of the mag pick up. Did you stall the mag pickup IAW the TM?

 

[hcso2332]

If you are getting 0, (zero) volts AC from the mag pickup, while the engine is cranking over, the mag pickup is bad, or mal adjusted. I assume you read the procedure in the TM for testing and replacement of the mag pick up. Did you stall the mag pickup IAW the TM?

Ok, idiot award to me, I misread your post and measured the leads going to the mag pick-up....... Just measured like I was supposed to and got 3 volts.

 

[Guyfang]

Good! If it the worst thing you do in life, your golden!

You ou said your getting 24 volts "for a blip" at S1. By that do you mean when you mesure at the S1 on pin 7, that you get 24 volts and it goes away? Because as long as you hold S1 in the start position, you should get voltage there. So when you hod S1 in the start position, what happens?

 

[hcso2332]

Good! If it the worst thing you do in life, your golden!

You ou said your getting 24 volts "for a blip" at S1. By that do you mean when you mesure at the S1 on pin 7, that you get 24 volts and it goes away? Because as long as you hold S1 in the start position, you should get voltage there. So when you hod S1 in the start position, what happens?

Just tried it again and I do have a constant 24v on #7 when holding the start on the S1

 

[Guyfang]

Next mesurment. While holding S1 in the start position, voltage goes to K15 coil. The K15 kloses contacts, allowing voltage from pin 7 to go to the A1. So hold up the S1 and mesure at F+ on the A1. You should get 24 volts. Now it's 24:30, so you got it from here. It's bed time for this old soldier.

 

[hcso2332]

Thank you for your help Guyfang. Your a great asset to SS! I'm done for the night as well and will hit it 1st thing in the morning.

 

[hcso2332]

Next mesurment. While holding S1 in the start position, voltage goes to K15 coil. The K15 kloses contacts, allowing voltage from pin 7 to go to the A1. So hold up the S1 and mesure at F+ on the A1. You should get 24 volts. Now it's 24:30, so you got it from here. It's bed time for this old soldier.

I have 24v coming out of K15 but only 8.99 volts at A1 F+

 

[Guyfang]

From S1-7 wire # 140A goes to TB5-14
TB5-14 wire #140C goes to K15A coil
K15B coil wire# 100AH to TB5-10 (ground)

When all this happens, (can you see the little red flag in K15 move? Close?) Then set of K15 contacts closes.
K15-8 #151A to R14-1
R14-1 through R14, out on R14-2, through CR2 and comes back out wire# 104D to TB5-17. Because of the R14, the voltage should be lower.
TB5-17 wire # 104C to A1-6

check all that, voltage and feeli-touchi. see if screws are loose and if connections are good or maybe broken.

 

[hcso2332]

Well I though I had it. R14 was getting 26 volts on one side and 9 volts out the other side. I checked another working generator I have and the R14 had 25 volts on each side. I then removed an R14 from a parts unit and installed it on this 803 and got the same results as before but instead of 9 volts I got 10 volts.

The R14 I removed was tested and showed 20 ohms which is in appears to be in spec.

What voltage should be coming out of R14?

 

[kloppk]

...What voltage should be coming out of R14?

Just checked using my 802.
I get 8.5 VDC while holding S1 in the START position.

Do you get any HZ or AC voltage reading on the panel meters with S1 in the START position?
Is S6 set correctly?

 

[hcso2332]

Just checked using my 802.
I get 8.5 VDC while holding S1 in the START position.

Do you get any HZ or AC voltage reading on the panel meters with S1 in the START position?
Is S6 set correctly?

I have no HZ or AC voltage. From my interpretation of Guyfangs guidance - I should be getting 24v to A1 6 on the A1 but I am only getting 9 volts.

I have 26 volts leaving the K15-8 to the R14. 24v leaves the R14 at 10 volts to the CR2 and then back to TB5-17.

 

[kloppk]

Just checked. I get 7.5 vdc at A1-6 with S1 in Start position.
Guy did indicate the voltage out of R14 will be less than 24 volts, a change from what he posted earlier in the thread.

 

[Guyfang]

That's the reason R14 is there. To lower the voltage/amperage. 8.5 volts sounds about right. So, if you have 8.5 volts on the A1-F+, and no volts or hertz reading, we need to maybe look into the TM to find the procedure to test the Excitor circuits. Because 8.5 volts is way more then is needed to light off the main gen.

 

[Guyfang]

Just checked. I get 7.5 vdc at A1-6 with S1 in Start position.
Guy did indicate the voltage out of R14 will be less than 24 volts, a change from what he posted earlier in the thread.

correct. It's been a while since I looked at the circuit. Getting old.

 

[Guyfang]

Go to PDF reader page 183, of the -24 TM. There you will find the trouble shooting procedure for checking the Excitor circuit. Print it out and follow it.