Electrical issue (about to pull hair out)

[MikeSVBC]

Damndest thing I've ever seen out of one of my A2 Japs. I come back from the Labor Day weekend to find lane 3 completely unresponsive. It is not in a blackout situation (machine is resting normally at 0/1st ball - I'll expound on this in a second) and after 2 days of troubleshooting, this is what I've learned. It is NOT the following: 1)turret jam or deck jam switches (both are new, buttons properly depressed, Ohms correct across TS2), 2)manager control or scoring control wiring (removed cannon plugs and tried jumper on both, no response), 3)100V contactor or 24V motor start relay (continuity and Ohms across coils are fine), 4)thermal overload (again, continuity is fine, overload was not tripped), 5)mechanic's rear switch (switch firm, wiring good, again Ohms across TS2 are good), masking unit switch (swapped w/ lane 4....works fine). In addition to these, I have good voltage on both sides of the circuit breaker, and I know the motor itself is fine and that this is not an electrical short, because I can do that thing that we all do when necessary, but tell our guys in the back to NEVER do, which is hold the magnetic contacts in with a screwdriver blade....and the lane will not blow the 3amp fuse, nor will it short/ "smoke" a part or trip the breaker. I held it in for 10 minutes and the thing ran fine. Only thing I know to do next is change the transformer, however, I was getting 28-29 volts to the 24V start relay, and in the 15 years I've worked on these machines, I have never seen a transformer just quit, so I'm hesitant. Any help would be greatly appreciated....would like to get this handled before the boss gets back from the Richmond race....hope he gets rained on, lol

[jim_long]

" I was getting 28-29 volts to the 24V start relay "

Was the motor start relay pulling in?

[Steve Stafford (JBEES)]

Mike...I need you to read some voltages.

TS2-6 to TS2-9
TS2-5 to TS2-9
TS2-3 to TS2-9
TS2-2 to TS2-9
Coil of the motor start relay.

Post results or give me a call and I can walk you through the procedure.

[MikeSVBC]

thanks jim.....no, relay was not pulling

[MikeSVBC]

thanks steve.....will post Fri night.

[Steve Stafford (JBEES)]

If you read that much voltage at the coil of the motor start relay and it is not pulling in...the motor start relay is bad and should be changed.

You stated that the ohms of the coil of this relay was good...how did you check the resistance of the coil? One leg of the coil must be isolated from the circuit by removing all wires going to it.

[jim_long]

Steve,

That's the part that got me. Jap MSR's rarely go bad. Yet he has voltage and continuity?

[MikeSVBC]

yes, I removed the wires from one of the coil terminals before measuring.....I actually swapped that out first with a brand new 24V relay still in the wrapping, but when the meter readings matched, and there was still no response, I put the original one back on.

[MikeSVBC]

and you're right jim....none of the stuff in these boxes goes bad usually (unless there's a short)....it's got me bumfuzzled

[Steve Stafford (JBEES)]

Measure the voltage again at the coil...along with the other points and let's see what you get before we start guessing as to the issue. I'm sure we can find the issue.

[Marty Murphy]

yes, I removed the wires from one of the coil terminals before measuring.....I actually swapped that out first with a brand new 24V relay still in the wrapping, but when the meter readings matched, and there was still no response, I put the original one back on.

Just because I have done this before - you sure its got the 24 volt relay and not the 100 volt relay in the 24 volt spot?
I did that once before and drove me crazy trying to figure it out.

Marty - Pro Bowl West

[Steve Stafford (JBEES)]

....would like to get this handled before the boss gets back from the Richmond race....hope he gets rained on, lol

I hope he doesn't...that means the race might be put off until Monday and I will miss it!

[MikeSVBC]

Sorry Steve.....unexpected parental issue keeping me from the center today.....will post those V readings late tomorrow night after work. Thanks again. (and it was the 24V, but I probably would have put the 100V on by accident myself if I'd had one, lol) ;-)

[Ted]

Some may say it's not Kosher to test it this way, but I bypass the safety switches for a second to see if I can make it come on. Jump a wire from 6 to 2, 6 to 3 then 6 to 5. If it comes on, find which one by jumping 2 to 3 (Deck jam), 3 to 5 (Turrett jam) then 5 to 6 (Rear switch) to isolate it.
I have alligator clips for my meter so I can hook it up to the start relay coil and watch it as I'm jumping switches to see if I get 24 VAC any time. Of course, you only need to do this if you also suspect the start relay coil is bad.

One final thing that can make you leave the machine with locks of human hair in your palms is a faulty main breaker. You can measure 115 on each leg to ground. But to see if it's bad, you have to get 208 or 230 between the phases on both top and bottom when it's on (speaking from experience).

[Steve Stafford (JBEES)]

Ted...nothing really wrong with that as long as the motor is unplugged. Parts can break when the motor is plugged in and folks do that. Bad things man...bad things.

You can also do that same check by reading the voltage drop across each of those points. When you find the 24 volts dropping across those two points...you have found your open circuit.

Also...I always recommend reading voltage to points within the circuits...never to ground as that can lead to false results. I think you have found that too with the circuit breaker issue.