Mep 803a no power

[Guyfang]

Correct. When you turn S1 to the start position, DC voltage excites the G1, main gen. When you release the S1, the volt regulator is powered by AC from the G1.

 

[Chrkjones]

They don't read shorted and I tested in circuit with a 9 vdc batt and the MOSFET's fire as seem as should. I am at a loss. I am showing 60 HZ on freq meter and I perform the test in the MEP-803a manual and get all readings but on 7 & 8 I read nothing while holding start and after changing diodes, I get 2 vac(should be 67.5-90 vac). The manual then states, if steps... are as indicated, voltage regulator is bad. I believe it should read, Not as indicated, because each step reads what it Should read.

 

[Guyfang]

Don't make this more complicated then it is. If the S1 lights off the G1, and it produces the proper voltage until the S1 is released, and then output voltage drops to 22 volts, it can only mean that the A1 is not taking over the function of Voltage regulation, for some reason. The main gen, is the main gen. If you apply voltage to F1 and F2 and the G1 lights off, its good. You need to test/repair the A1, or replace it. Then you can go on to other possibility's. And there are a few.

 

[emndive]

Silly question.... should the AC interrupter be open or closed with normal operation? No power to lugs and didn't want to "mess" with anything. Thanks guys!

 

[Guyfang]

When you want to turn on the power, turn on the interrupter.

 

[Light in the Dark]

You want to 'close' the circuit, which is what then sends power to the lugs. To discontinue power to the lugs, you 'open' the circuit.

 

[emndive]

the light comes on with "open' circuit?

 

[Zed254]

Closed circuit completes the electrical path and the idiot light comes on. Open circuit cuts the light off. On the 803 the closed position is with switch clicked up. At this point the light should come on. Cover the light when in the down position because the lens seems to pull in surrounding light and looks to be lit up. Check the labels on the control board. The TM will give you step by step instructions for start up.

 

[Light in the Dark]

If your light comes on when its set to open, maybe the switch is upside down on your machine (like someone took it out and flipped it). I am not in front of my set, so I am not sure if thats even possible (I know some of those features on the gauge panel have little dog legs for alignment)?

 

[Zed254]

Excellent tip Light in the Dark: just checked mine and there is a dog leg / tab and a hole on the bottom of the switch position. Emndive, check visually to confirm that there is a tab in the hole below the switch arm. OEM switch should be mounted correctly with tab on the bottom.

 

[emndive]

I should be all set, nothing was tampered with. I had no power to the LUGS but I didn't have the switch on (or in the correct position). Thanks guys

 

[Guyfang]

Perhaps, a little light reading, in the operators manual might be a good idea.

 

[Light in the Dark]

Perhaps, a little light reading, in the operators manual might be a good idea.

Not just for surgeons I hear!