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Author Topic: How to test u45 on system 11  (Read 292 times)

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Offline Pinball tragic

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How to test u45 on system 11
« on: December 30, 2015, 02:04:43 AM »
Hi guys
I think I have a bad u45 on my system 11 tomcat. My pop bumper charges when the machine is turned on. Transistors 68 and 69(I think these were the ones) were fried and resistor 94. Changed all these but the resistor has a weird reading after I put it in. Got a reading of 12 when on the board. Took it out and got an 800 something reading. Could a bad u45 do this?
Thanks for any help.
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Offline Retropin

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Re: How to test u45 on system 11
« Reply #1 on: December 30, 2015, 10:23:23 AM »
You cant test resistors once on the board unless you lift one leg to remove it from circuit.
 Once its on the PCB, your meter will test the resistance of anything in parallel with it also which is what's happening here.
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