MEP-803a no longer works correctly

[SteveJennings]

Have a 803a with 3300 hours that I’ve owned for couple years. Always ran good, maintained and load tested regularly. Started it the other day after sitting over 6 months and no power. So I tried to read the -24 and the schematics (which are greek to me). Also been searching similar posts on here.

Here’s a summary of what it’s doing and what I’ve tried.

When I flip the A/C interrupter switch on I have no green light and no power at lugs (although sometimes green light flickers). However if I hold the switch up I get power at the lugs. As soon as I release the switch I lose it. I have power at convenience outlets, volts and HZ gauges read, and no fault lights. Turned on battle short switch (battle short light does work) and still no green light or power at lugs. Sprayed the interrupter switch with contact cleaner and worked back and forth probably 20 times, and sprayed and worked all other switches that seemed pertinent. No luck. Had a buddy help me pull the top cover off to clean and test K1 and it tested good, contacts look great. Started it back up and still no power to the lugs.

My buddy mentioned it might be the overload/short circuit relay but he hasn’t been back and I have no idea how to check it.

Anyone have any ideas on what else it might be?

 

[Guyfang]

Steve,

Ok, lets start with what you told us.
1. The set starts up right. Shows volts and freq on the meters.
2. You have 120 volts on J1, (120 volt outlet).
3. When you flip up S5, (AC Circuit Interrupter Switch) it sometimes shows a flickering green light on DS7, AC Circuit Interrupter Light) and sometimes not.
4. If DS7 comes on, and you have power at the load terminals, when you release S5, the DS7 goes out, and you lose power at the load terminals. Correct?

Try this. Start the set. Flip up the S7 Battle short switch first, and then flip up the S5 switch.
1. Do you have a DS7 green light?
2. Do you have any light come on the A2, (Malfunction Indicator).
3. Do you have power at the load terminals?

I suspect you need to remove K1, and take it apart. It may have water in it, or is rusted/corroded up.

If you answer these questions fast enough, you will catch me before bed time. If not, someone will probably jump in. I will be back Sunday night.

 

[SteveJennings]

Yes as long as I hold S5 up I have power at terminals. After I release S5 I lose power at lugs but sometimes DS7 continues to flicker until I pull down on S5. Flickering does not always happen, sometimes no light at all.

when S7 flipped up before S5 still no power at lugs. No fault lights either.

Have taken K1 completely apart no sign of water contacts nice and shiny. Bench tests fine.

 

[69birdman]

Yes as long as I hold S5 up I have power at terminals. After I release S5 I lose power at lugs but sometimes DS7 continues to flicker until I pull down on S5. Flickering does not always happen, sometimes no light at all.

when S7 flipped up before S5 still no power at lugs. No fault lights either.

Have taken K1 completely apart no sign of water contacts nice and shiny. Bench tests fine.

I had an 802 doing simular, use the wiring schematic to follow wiring from S5 to k1 ,checking for continuity along the way. I lost continuity going through J7 plug , open right door look up, I think the lock ring twisted 90° and plug pulled strait down? (Poor memory) Sprayed contact cleaner in both sides, cured my problem.

 

[SteveJennings]

I had an 802 doing simular, use the wiring schematic to follow wiring from S5 to k1 ,checking for continuity along the way. I lost continuity going through J7 plug , open right door look up, I think the lock ring twisted 90° and plug pulled strait down? (Poor memory) Sprayed contact cleaner in both sides, cured my problem.

Does J7 pull straight off or twist and pull? I see no locking ring on any plugs and they don’t seem to twist or pull. Afraid to break so asking before I try to hard.

 

[69birdman]

Does J7 pull straight off or twist and pull? I see no locking ring on any plugs and they don’t seem to twist or pull. Afraid to break so asking before I try to hard.

Through right rear door , first plug up should have upper twist lock ring, loosen it , and pull plug strait down, Mark orientation prior to pulling.

 

[SteveJennings]

Well I feel like an idiot! My buddy had mentioned that it might be the overload/short circuit relay last time we spoke. So I decided to check connections for corrosion and found this wire that must have vibrated off. Put it back on and it makes power like it should again! Green light still not working unless I push in to test it. But can live with that.

Thanks everyone for your help and support.

 

[SteveJennings]

 

[Guyfang]

Then check the circuit.

 

[Ranger Danger]

I'm having the same issue on an 802a. I thought the S5 had gone bad so I replaced it. Still nothing. I'll look at the recomendations here before I continue. Thanks for the help.

 

[kloppk]

Be sure the diode CR3 is there. Without it the contactor will not stay closed.

 

[Guyfang]

Then check the circuit.
View attachment 841889

I should have added, to check for DCV at terminals 11 and 12 on the K1, when you have output on the load terminals. That set of contacts tells DS7 to come on.