Pole position issue cpu board issue

[NoQuarter]

Hello, Brand new to this and i just picked up a pole position. obvioulsy the game will not turn on one of my AR II boards is bad and not putting out the correct voltage. but my other ar II board i believe is good, when i hook it up to my Video board i get the red led to come on, but when i connect it to my cpu board the led comes on but dims out with a second or two. when i have it connection to the video board i get around +5 volts connected and testing at the test point, when connected to the cpu board im at around 1.2 volts.. how screwed am i?

[P-feif]

Sounds like a short.

[NoQuarter]

You are right thanks, it does seem like it is shorted somewhere. or I'm thinking a bad ground.. i will triple check the wiring harness, would anyone know if there is a good place to look on the board for this type of issue?

[NoQuarter]

Definitely a short, 5v+ beeps on a continuity test to ground. Something's wrong with the board.... Now trying to find out what. Can anyone tell me if a cap should beep when testing continuity over its leads on the board?

[P-feif]

I think anything will if it's soldered to the board.

[NoQuarter]

just an update on this, with the help of a local electronics repairman. we were able to find the short and replace the part. it was the Diode at cr2 in4735a i believe.

I have rebuilt one of arII board and am now getting 5.17 V from each board no load, when connected to the board i get 4.77/4.86 volts. getting both led lights on.

i was having an issue where the monitor was giving me a pink screen with "raster lines" (I believe its called), so I checked the video input. connections looked good, so i moved on to the dials on the fly back. i adjusted the screen dial and i got some video.

Unfortunately i am getting a Ram 8 Error. after doing some research it looks like this error may be coming from the part of the board that has to do with the battery. the old battery has been removed and there is definitely some corrosion in the area. looking more closely i see that Q4 one of the transistor legs is broken. i dont have enough of the leg to solder it back so ordering parts it goes..




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[iankellogg]

The entire point of the battery repair kit I put together fixes exactly the two failures you are talking about. CR2 is one of the most common failures with the battery acid damage chewing up the NVRAM enable pins.

[NoQuarter]

Thank you Ian!, I successfully replaced the Transistor at Q4... this lead me to an RAM 0 Error on screen. after some more research looks like i have to replace an ram chip on the video board 8F i believe. luckily i ordered extra ram chips with my battery kit from Ian. but before replacing the chip since i dont have a good desoldering iron, i wanted to try cleaning the back of the board. it had a spongy type materials looks like it was supposed to separate the boards so they do not touch. any way i cleaned the area where the ram chip was. BINGO!!!! game booted up .

still haven't tested the game i need to rebuild my utility panel... also my coin mechs are missing, but im soo close :p