120/208 MEP003A No 208v output

[Genvsolar]

Hello guys, I have a quest about my MEP003 set and hope y’all might be able to point me in the right direction.
I have a set I am using overseas that has been working fine up to now. The problem is we would start the unit and we got no output power. After some testing, we realized one of the diodes was bad and had to change it (see picture). After replacing the diode, we ran the unit and this time we got 120v/240v single phase but no 208v 3 phase. What do you think may be the issue here? My maintenance guy is performing more testing to try to find the problem. I am thinking maybe we have a bad voltage selector switch at the 120v/208v 3 phase position. Your thoughts.

thanks,

 

[Ray70]

So your 120/240 is working but you get nothing on any leg when you switch the AC select switch to 208 3 phase?
And is this verified with a multi meter or are you looking on the volt gage on the machine only?
Also, if going just by the volt gage on the machine, are you switching the AM/VM switch to the correct position?
Either way if you have 120/240 but not 208 the AC select switch contacts are probably dirty.
I assume the switch snapped into position correctly and isn't stuck between or beyond position?
If you don't typically need 208 3 phase I would suggest leaving the switch in the 240 position because these switches are notorious for getting stuck!
If you wan to try to fix it, open up the side panel, loosen the nuts on the long threaded rods holding the switch assembly together, spray Detoxit or other electrical cleaner into the switch segments and work the switch back and forth many times.
Also clean your AM/VM switch while you are at it, for good measure.

 

[Genvsolar]

So your 120/240 is working but you get nothing on any leg when you switch the AC select switch to 208 3 phase?
And is this verified with a multi meter or are you looking on the volt gage on the machine only?
Also, if going just by the volt gage on the machine, are you switching the AM/VM switch to the correct position?
Either way if you have 120/240 but not 208 the AC select switch contacts are probably dirty.
I assume the switch snapped into position correctly and isn't stuck between or beyond position?
If you don't typically need 208 3 phase I would suggest leaving the switch in the 240 position because these switches are notorious for getting stuck!
If you wan to try to fix it, open up the side panel, loosen the nuts on the long threaded rods holding the switch assembly together, spray Detoxit or other electrical cleaner into the switch segments and work the switch back and forth many times.
Also clean your AM/VM switch while you are at it, for good measure.

Thanks for the advice Ray70. Yes we had the AM/VM in the right position and used a multimeter. We have done this countless of times before with good results. I think you might be on to something about the switch being dirty. That was my original thought. This switch has been acting up lately and maybe it just needs some maintenance. I would be find with the 120v/240v except some of my machines use 3 phase power, so I need that 208v. I will do some cleaning and operate the switch some to see if that helps. Thanks