just got a pinball has a project and was wondering what it means by the cpu board having two red lights that come on when it boots up.

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okay , i looked over that and it said to check things on table 13 , but the only thing i am unsure about is what 3d6 and 3d7 are.
nexr , it says to remove driver board from cpu board which means all cables including the 40 pin connecter at the top?

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are the 3d6 and 3d7 the diodes beside the power plugs from the transformer ? could not find power supply schematics in the manual.

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measured 3J6 , there is 12+v unregulated output but no voltage on the 5 volt pins.

okay i changed the fuse on f5 and it now show between 3 to 4 volts on the 3J6 vdc pins , but that not enough voltage is it?

how do i measure the 5v transistor LM323K to see if its causing low voltage?

i cleaned the connecters and it is getting 5v now but now showing no lights on the cpu board.

okay now the 12+v unregulated is now 9 volts , so i think i will need to change the fuse holders and reflow solder joints because after getting a better look at it after taking it out , the fuse holders are rusted and solder joints look cracked or corroded.

the 2 red leds came back on after testing the volts again which are normal (12v and 5v). it was the fuse clip that was causing the low voltage
i already took the driver board out and tested just the cpu board and it still shows the same 2 red leds locked on.
i think the only solution is get to get a new cpu board and driver board. Is the rottendog mpu327 any good? i cant find one in stock.

the only other thing it could be is that there is a flipper coil where the wiring broke off the solder joints , would that cause the mpu not to boot?

the voltages from the power board seem normal , it the cpu mpu that i cant find the problem with.
i tried it with the driver board removed and it still does not blink . i think its all the rusted ic chips and corroded solder joints on the board that are causing the problem but i just don't have the skills to replace ic chips.
i think i going to get a new mpu like the rottendog mpu 327. is it any good? been trying to find one in stock.

okay , i may get the pinballpcb.com replacement boards . i will get the cpu board first and then get the driver board if the original one does not work.
is there any way to test if driver board is working without a working cpu board.?