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(Topic ID: 275712)

Switch matrix problem : Column "flickering"

By giligold

69 days ago

Topic Stats

  • 3 posts
  • 3 Pinsiders participating
  • Latest reply 62 days ago by frunch
  • No one calls this topic a favorite


Linked Games

#1 69 days ago

Hi All,

I'm new t the pinball world and this is my first post ever so please be gentle with me if I'm asking a stupid question or posting at the wrong sub-forum.

Here is the thing: I have a dirty Harry (bought it a month ago worked very hard to bring it to a very good state).
When I put it in a switch test mode, Column 1 switches 1-7 (but not switch eight) "flicker" for a fraction of a second every 2-3 seconds. If the single switch tested at the time belongs to column 1 you see it on a close state each time the column flickers.
Actually this doesn't effect anything in the machine. Except when I try yo enter initials after high score: You can scroll through the letters with the flippers but letters are entered as if the start button was pushed randomly (this what made me look for a problem on the first place).

When I disconnect J207 and J209 the problem disappears - so i assumed it's not a board issue. Nevertheless I replaced U20 - it didn't change anything.
I've examined all column 1 switches visually for problems and examined connectivity between all of then but everything seems just fine.
I don't know how to continue. I'd appreciate any suggestion


#2 67 days ago

Can anybody help the new guy out?

#3 62 days ago

I don't have much experience with this era of games, but i might be able to help. At very least, it'll give this topic a bump back to the top and maybe some of the more experienced folks might chime in.

You said you examined the column 1 switches, but one thing that wasn't noted was whether you checked the diodes on the switches. If one of them is broken or shorting to something else nearby, that might explain the behavior.

Another thing to try would be testing the columns and rows using a jumper wire. Remove connectors J207+J205 and connect an alligator jumper (a piece of wire with an alligator clip at both ends) to pin one of J207. Touch the other end of the alligator jumper to pin 1 on J205. Note which switch(es) activate. Keep the jumper clipped to pin 1 on J207 and touch the other end to pin 2 of J205, then pin 3, 4, and so on to the end of the connector. Does each pairing only register as one switch, or does the problem still happen when using a jumper?

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