Mep-804a no output. With video

[MAdams]

I finally got this generator running after replacing S1 but it has no output voltage other that the 6v exciter. No fault lights, and same results when the battle switch is on.

Here is a link to a crappy video

https://youtu.be/UzrAwGMIK1s

 

[Guyfang]

Open up the control panel and see it the quad circuit fuse is blown. If you do not know what that is, open the control panel and take a picture. We can work from there.

No use turning the Freq control knob. The freq control is the knob and cable under the control panel, right side.

 

[MAdams]

These are the only two fuses I know of. Pic 2 is hard to see but it has an exposed fuse element

 

[MAdams]

 

[MAdams]

 

[Guyfang]

The picture in post 4 is the one you want. The item in post 5 is called a Ammeter shunt. Its not a fuse, persay. There is another fuse in the control panel, FU1, but as you know its for the DC side of the house.

So test the fuse shown in post 4. If its bad, and you replace it, and it blows again, DO NOT, repeat, DO NOT fool with it any longer. Your volt regulator is bad. Do not under any circumstances jump that fuse. You will destroy your windings in the excitor/windings.

 

[MAdams]

The fuse in post #4 ohms out as good. I did not start the generator but with S1 in the run position there is no voltage at the fuse.

 

[kloppk]

The fuse in post #4 ohms out as good. I did not start the generator but with S1 in the run position there is no voltage at the fuse.

Did you check for AC voltage across pins 1 & 3 of the regulator?
You can measure the same points at pins F & J on the Diagnostic connector instead.

 

[Guyfang]

With the S-1 in the run position, you should not get any voltage at the fuse, Only when you start it, hold it in the start position and the starter has been locked out, should there be voltage at the fuse. If you have voltage at the fuse, then follow in KLOPPK's message # 8.

 

[MAdams]

I'm only getting 1.2vac on both sides of the fuse. I double checked the mag pickup. It reads 800omhs and 2.5vac while using the dead crank switch

 

[Guyfang]

Do you have 24 volts on pin 7 of the S-1 start switch, while holding it in the start position? That is the wire needed to flash the fields. That is wire number 190A.

 

[MAdams]

I do get 24vdc on pin 7 when S1 is held in start. Also, with the battle short switch off, I get 11v at the fuse when holding S1 in start. With battle short on, I get no voltage at the fuse

 

[Guyfang]

Then get the schematic out and follow the path. From pin 7 to.......................

Get someone to help, it easier then doing it yourself.

 

[MAdams]

Wire 190 goes from S1 to K15 relay. I swapped the relays around but still no voltage at the fuse.

The fuse wire is 141. It also goes to K15 and also goes to TB8 (in pic) which then 141 turns into a large diameter wire and goes directly to the generator.

 

[MAdams]

K15 has a diode that initially looks out is place but it's shown on the TM. It goes to K12 and checks out .480 volt on my dvom.

After all that, still only 11v at the fuse when S1 is held on start

 

[Guyfang]

11 volts is enough to light off the main gen. If you have voltage at TB-8 then you need to pull off the end bell housing ad look there.