Mep 802a keeps dropping out ac power at lugs only

[Windowlicker]

So give you some history. Unit works fine untill theres a change in load added or Removed. Relay opens and short cirucut light and sometimes over load light comes on not at same time.Convenience plug works just fine.
I dialed voltage and hrz in with hand held meter gauges on the unit are off on both voltage and freq working but not read the same as rms meter dont really want to burn up Electronics in the house by setting the unit Gauges to to 60 hrz and 120 volts to see if it shuting down on Safety Side note, I got this unit for my parents. I have one myself that I've been stripping parts off to make this a whole unit. Any help would be greatly appreciated.

 

[Ray70]

I'd start off by exercising and cleaning both the AM/VM switch and the AC select switch inside the control cube.
What you are describing is a classic case of oxidation buildup in the internal contacts of the switch assemblies, causing incorrect load readings.
Lots of folks here recommend Deoxit contact cleaner.... seems to perform the best, but any electrical cleaner should help.

 

[Windowlicker]

Ok i will get a can of deoxit 5. Clean all the contacts, cubes and switches. Thank you for the help i will get back to you

 

[Ray70]

Get the spray inside the switch and rotate the switch a bunch of times, then repeat.... only hard part is that you really need to remove the top cover to access the body of the AC select switch.

 

[Light in the Dark]

And make sure your batteries are disconnected during all this. I agree with Ray, sounds like you need some magic in a can to fix a phantom problem.

 

[Windowlicker]

Ok cleaned every thing gauges are reading better. But when i close ACI switch short circut light comes on. When i close ACI switch hz goes from 60 down to 57 hz only when load is on unit no change with out load. Looks like s8 and k1 have been replaced along with voltage regulator found magic marker on all terminals. Voltage gauge is now reading right so thats a step in right direction going to take k1 apart and clean it I will post more if i find anything

 

[Windowlicker]

K1 is ok have found unit goes out on short circut when turning the am-vm and if i leave swicth in 9 oclock i can turn loads on and off with no short circut light coming on and power staying at terminal lugs going threw s6 switch to check wires cant find a diagram with wire ids on it you any one have this?
I just want to say thank you so much for your help

 

[kloppk]

.... cant find a diagram with wire ids on it you any one have this?

That info is in the back of the -24 TM. This is for the 802A and 803A

 

[Ray70]

When checking these connections, use your meter and verify all the internal jumpers are in place. All the dark lines on the schematic above indicate internal jumpers such as 4,8 and 12 are all jumped together as are 2,6 and 10. Not long ago I worked on an 802 for another SS member. Someone had replaced the AM/VM switch with what appeared to be the correct switch, but all of the internal jumpers were missing. This caused a different problem than yours, but something to verify while you're in there!

 

[Guyfang]

When you at last figure it out, I anyway, want to perform open heart surgery without any happy juice on the fool who took out the jumpers.

 

[Ray70]

The crazy thing is, that switch has the jumpers internal to the switch. You can see the copper legs if you look closely inside the terminal lugs, they are somehow installed from the inside when the switch is manufactured. This switch didn't have any of them installed from the manufacturer..... but perhaps they sell the same switch without jumpers under a different PN, and someone ended up with the wrong switch.... put it in, it didn't work and off the set went to the auction block! ?? who knows! Installed about 18 home made jumper wires and it was working correctly.

 

[Windowlicker]

Thank you will get back to this weekend. IF i leave av-am switch at 9 oclock on L2 setting will the overload and short circut still work? I am running unit at 120/240 single phase

 

[Guyfang]

Of course it will work.

 

[Light in the Dark]

The AM-VM only tells the gauges what to read... so while it might work in that setting, you need to chase the gremlin out.

 

[Light in the Dark]

What is your S8 set to, that you are pulling 120V only off L2?

 

[Windowlicker]

No i am pulling 120 from L1 and L3
S8 set to 120/240 single phase

 

[Light in the Dark]

Does your percent rated current gauge (M8.) register in this 9 o clock position, as you have it set up?

 

[Windowlicker]

It moves but I haven't confirmed with handheld meter of how much it's actually drawing to see if it's accurate.

 

[Light in the Dark]

If your machine is set to produce 120/240 1PH, the L2 will have no current present. And the AM/VM in the 9 o clock position (if you look at the printed info on the gauge panel face) is operating at 3PH, picking up voltage for the gauges off L2-L3 (L3 is common amongst almost all voltage settings), and the amperage is being measured on L2. So there should be no gauge activity as your machine is described.

...which unfortunately means that I think your S8 (and possible more) is either miswired, or is missing internal contacts like others have said for S6.

I think you need to see if there is current on L2, without changing any settings on your machine. You do need to ensure this puppy is properly grounded though, as if something IS miswired, the electricity running through this machine cannot be trusted. Tread carefully.

 

[Windowlicker]

Yes i am going to check the wiring on s6 next then pull switch apart to clean it .the only way i can get unit to run with out droping out power on short circut is if i leave the s6 switch at 9 oclock or l2 if i turn the switch when unit is putting out power short circut