My first MEP 003a A few problems, could use some advice

[hogpatch]

I bought my oo3 1 week ago. I've been reading your posts trying to learn enough to check it out & maybe ask sensible questions. It runs great, But no output. The DC generator under flywheel checks good except when you check across both leads while running, only 27 or 28 volts ( I'm thinking I may need to pull flywheel & clean it). The capacitor at the bottom of the regulator(rectifier) has wire broken( I need the best place to find it) I flashed the generator while revved & Hertz meter & volt meter came right up to 62 hertz & 118 volts. Soon as I stop flashing it drops immediately ( I'm thinking one or more of the 6 rotating diodes are bad? If so, where to find them & are they cheap enough to just replace them all?) Also, on the A-4 board, cr2 & cr5 diodes look to be burned. Are they in the exciter circuit & can they be replaced on board without having to re-place the whole board. I also checked & cleaned the frame ground.( It was ok as this machine doesn't seem to have any corrosion problems) It is on covered trailer. Should there be any spark when connecting battery cables after they have been disconnected? I would like to make a list & order all parts needed soon. I would appreciate any help I can get .

 

[n1oty]

The field flash diodes and circuitry sound OK. I think you have a problem with the voltage regulator. Follow the guidance in the TM's for checking the VR.

John

 

[hogpatch]

I downloaded the manual today, I'll test the vr tomorrow, Thanks

 

[Triple Jim]

Also, on the A-4 board, cr2 & cr5 diodes look to be burned. Are they in the exciter circuit & can they be replaced on board without having to re-place the whole board.

Yes, the diodes can be changed. You should be fine with any of the inexpensive 1N400X diodes (1N4001, 1N4002, etc. where higher numbers are rated for higher voltages). Check and replace any bad ones. Many digital meters have a diode test function. Otherwise, use a low current test lamp to verify they conduct in one direction but not the other.

 

[bsorcs]

Gentlemen, I am consistently amazed and impressed at the promptness and quality level of the support available on this site. Hats off once again!

 

[hogpatch]

I'm still needing a usable part# and place to buy 6 rotating diodes in the exciter. Can anyone help me with that?

 

[Isaac-1]

According to the TM the numbers for the rotating rectifier diodes are S6248 and S6248R (3 of each, the R's are reverse mounted) these are threaded stud diodes, you may have to search the specs and find another similar spec threaded diode with the same size spec from your preferred electronics parts supplier (Mouser, Digi-Key, Newark, or even on ebay). Before assuming these are the problem I would suggest double checking the rest of the voltage regulation system as these diodes don't seem to fail very often on this model.

Ike

 

[Jimc]

The diodes are cheap. Few bucks a piece. There are six total 3 one direction and 3 reverse as mentioned before. All the normal places like newark and digikey never have them in stock. I order them from allied electronics. They always seem to have them.

 

[Munchies]

The diodes are cheap. Few bucks a piece. There are six total 3 one direction and 3 reverse as mentioned before. All the normal places like newark and digikey never have them in stock. I order them from allied electronics. They always seem to have them.

JimC, what part # are you using for the diodes via allied electronics?

 

[Rapracing]

Sounds a bit familiar to me.


http://www.steelsoldiers.com/showthread.php?112824-NO-Voltage-or-HZ-reading-on-meters

I would try the test in post #40. It is really easy and quick to do. Just don't make the mistake I did and leave the battery hooked up after shutting it down. You can see the results of that later in the thread.

OOOOPS! My problem was with an 002. Maybe the test is a bit different for the 003?

 

[Jimc]

1n1204ra and 1n1204a.

both are about the same except one is reverse direction.