(Topic ID: 282825)

Jokerz won't start

By Noobpnbler

1 year ago

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  • 2 posts
  • 1 Pinsider participating
  • Latest reply 1 year ago by Noobpnbler
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    #1 1 year ago

    Hey all! New pinballer here. I recently picked up a 1988 Jokerz as a Christmas present for my 3 boys, but I need some help to get it going! I purchased the machine, knowing that the previous owner was using it, and it all of a sudden would not start game play and started humming loudly. I checked all the grounds, found 1 was loose. First off, when the power is turned on, some lights come on, accompanied by a very loud hum, no display, card wheel never turns. (From my reading this hum is a common issue) I changed the 3 "AA" batteries, no difference. I checked the board for heat, and found the transistor Q12, which I believe drives Q16, is getting extremely hot, to about 126 deg C before I turned it off. It does not get hot every time I power off then on, some times it stays around 40 deg c. I hit the reset button on the MPU for the CPU and the Sound, and all of a sudden it started working, sort of.... The 5 volt LED always comes on at power up, but not the other 2 (blanking and diag). When i hit the reset for the CPU, the blanking LED came on, and the diag flashed, then I was able to play the machine, but faint voice in the speakers, ill try and upload a video of what i mean. The ball got stuck in a hole, guessing the ejector isn't working too well, eventually popped up. I shit down the machine, feeling pretty good about making it play, then came back an hour later to find I was back at square 1, no display or game play, typical hum. Next, I noticed the fuses F2a, and F4 had blown. I replaced both with 2A slow blows, and within 30 seconds of powering on, the F4 fuse blows. Can someone shine some light on this for me please? Please find attached some pics of what the display said when I worked shortly. I am a licensed Heavy Equipment Mechanic and know my way around DC voltage with a DVOM pretty good, but have not ever tackled a pinball machine before! Thanks in advance!

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    #2 1 year ago

    I forgot to mention, the F2a and F4 fuses are on the Aux power driver unit board.

    Screenshot_20201201-170737_Drive (resized).jpg


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