MEP-016b low output voltage

[Isaac-1]

Before going through all the detailed trouble shooting steps I thought I would post the symptoms here and see if anyone has any thoughts on things to check.

My MEP-701a / MEP-016b was working fine until today, now it will have a max output of 101V in 120V single phase mode, as recently as last weekend the max output with the front panel knob turned up all the way was 126V. I have checked the front panel rheostat with my multimeter and while not perfect the output seems fairly smooth, also the frequency is a solid 60 hz. Usually when I read about low output voltage it is much lower than the 100V range I am seeing (front panel will adjust it from about 88V-101V), I should probably also note the weather has turned cooler here over the last couple of days, when I was using it last weekend the temperature was in the 90's, last night it dipped into the 30's for the first time this year.

Ike

p.s. I also cycled the output voltage selector switch, no change.

 

[derf]

I think I have a spare reg around here if you end up needing one. I have two 701As around here if you need them, too. I'll make you a deal on both.

First, check the convenience outlet voltage with your multimeter. You may just have a wacky panel gauge.
Next, as with all things electrical/electronic, check for flaky connections.
See what each winding is putting out with your multimeter.

 

[Isaac-1]

Thanks, already checked the outlet with a good meter (actually 2), I guess I will pull it this weekend and see if there is anything obvious, from there I will try to follow the steps in the trouble shooting list, need to pick up a 30 ohms power resistor first though. If I can't get it fixed I will probably drop in an SX460 clone in its place.

Ike

 

[Isaac-1]

Ok things just got more complicated, it seems this problem varies with temperature, today it was 82 degrees out and I was getting 112V or so with the front panel pot turned up (I did clean it, no change in max output, but it is less noisy in the adjustment range now). I was getting 126V max when it was in the 90's a couple of weeks ago.