Lincoln G8000 no output

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My trusty G8000 quit today.  When I try to strike an arc I get very weak sparks.  I tried changing polarity, amps, etc.  There's no 120/240 either.  I removed the cover nothing appears to be smoked.  Any ideas?  Think this old thing is worth fixing?  Thanx John F.
Reply:The first thing I would check is the oil pressure switch.  Many of the G8000s had a three terminal oil pressure switch.  If one set of contacts failed you get no output and no low idle, but the engine will still run.Good luck,Bob
Reply:ThanxI do get low idle.  Can the oil pressure switch be bypassed?  I also cleaned the slip rings, no change.  When a load is applied the engine goes to high idle but there's little output.  I plugged in a trouble light to the 120 outlet the filament barely glows.  I emailed Lincoln but I suspect they're going to say parts are no longer available.  I'm thinking something on circuit board went poof.John F.
Reply:The G8000 uses the same PC board as the Ranger 8, so they should be available.  It sounds like the oil pressure switch is probably fine, but you should be able to jumper it out to test it.  I think the wires are 210 and 212.  Check your wiring diagramTry putting a jumper wire from the negative terminal of the field bridge rectifier to the negative brush terminal.  Leave all the existing wires in place. (This bypasses the fine control transistor on the PC board.) If the problem is in the control circuit, you should get full output with no fine control.If it is a control circuit problem, check the potentiometer, the connections to the PC board, connections to the potentiometer, chassis ground connections.  Also make sure your battery is good and is charging properly.
Reply:CoolThe battery charges fine just no weld or ac power.  I'll try your suggestions.   Thanx againJohn F.
Reply:It's alive!  Thanx Bob for all your help.I bypassed the board...no change so I started pulling connectors apart.  One of the  other wires on the field bridge rectifier came off real easy.  The terminal obviously got hot.  I cleaned all the lugs on the rectifier they were all rusty and replaced the bad wire end connector.  I also applied dielectric grease to the connections.  These connections must have been bad for a while because the engine didn't speed up when welding ever since I've had it now it does.  I just manually put it on high idle before.  Let the arcs and sparks begin!John F.
Reply:Nice going, John.Bad connections in Engine drives are probably one of the biggest problems, since these units spend a lot of time outdoors.The idle problem fix was probably just luck, unless you went through the whole machine checking and cleaning all the connections.  That problem is normally caused by a poor connection in the weld current sense circuit.  This circuit runs from the back on one of the weld terminals, wraps three times through the PC board current sensor then connects to one of the terminals of the polarity switch.  All the connections in this circuit have to be PERFECT or you can have the trouble you described.Cheers,Bob
Reply:Yeah I unplugged every connector, cleaned and applied dielectric grease. I also bought can of switch cleaner and sprayed the switches an controls.  It's like a new machine!