Pinbot
Williams, 1986My Pinbot worked fine, but now when I switch it on fuse F2 (4A SB) on power supply blows after 3 seconds, it does not blow when I disconnect J11 from the CPU board. When J11 is disconnected the visor test works but it does not kick out ball and the ramp stays raised up.
I tested across all coils connecting to J11 and they all measure above 4 ohm.
What is the next step I should take to figure out the cause?
Quoted from Bumper:My Pinbot worked fine, but now when I switch it on fuse F2 (4A SB) on power supply blows after 3 seconds, it does not blow when I disconnect J11 from the CPU board. When J11 is disconnected the visor test works but it does not kick out ball and the ramp stays raised up.
I tested across all coils connecting to J11 and they all measure above 4 ohm.
What is the next step I should take to figure out the cause?
Most likely a shorted driver transistor since it blows just after power up. Check all of them that run through J11. Q22,23,24,25,30,31,32,33
TIP122/102: Put the black lead of your DMM on the center lead or on the metal tab of the transistor. Put the red lead of your DMM on each of the two outside legs of the transistor. You should get a reading of .4 to .6 volts. Any other value, and the transistor is bad and will need to be replaced.
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Berea, OH
