Slingshot Not Working, Flipper Making Noise

nrjones

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I am having two issues I hope someone can help me with. The machine is a Robocop by Data East.

1.) I installed a flipper rebuild kit last night and now the right flipper makes a buzzing, humming type noise when used. Didn't do this before I installed the rebuild kit.

2.) The left slingshot does not work. I have checked everything I really know how to check. There is continuity back to the board. The diodes are fine. New coil. There is a capacitor and resistor figured into the leaf switches...those are fine. I'm not too sure on how to test the transistors on the board. Can someone tell me how to do that? And what values I should get when I test? It definitely looks like some of the transistors for the solenoids have been replaced before. Oh, and I checked all fuses.

Any help would be appreciated.
 
I tested the TIP122 transistors. Most values were between .4 and .6 as the site says. Two readings were around .37, .38.

I then tested the 2n4401 pre-driver transistors. I was getting consistent readings of .130 to .150 on the collector side and .4s on the emitter side. So are these bad then? Should they be .4 to .6 on both the collector and emitter sides?

There are also appears to be a resistor thats bad. Looks like a 68ohm resistor right before the 2n4401 transistor. Its hard to read my manual...looks like it says 68ohm. Sound right?

So are my pre-drivers bad, but not the TIP122s? How are all these values so low but only one coil doesn't work. Seems like if the values are so low at .130 to .150 that other coils should be affected. No? Just one coil is not working.
 
Did you measure the resistance of the coil itself? Maybe it's open.

.003k ohms = leads on both lugs

.001k ohms = leads on both lugs with one wire off

.003k ohms = leads on both lugs, diode cut
 
3 ohms isn't bad...should be a little higher.Do you have voltage to the coils ?? The transistors ground the circuit to the coil.

Yes. I checked that earlier...couldn't give you an exact figure right now. Can check it again tomorrow for an exact voltage. But I recall that it was fine.
 
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