Williams Cyclone Display Segment Problem - Need Expert!

tjc02002

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Williams Cyclone Display Segment Problem

I have a Williams Cyclone with a display segment problem on the P1 and P2 displays(alphanumeric). Some of the segments are out and sometimes they come back on or flicker. Currently segments F, A, and D are out. Here is the rundown of what I have done:

A few months ago I replaced the player 1 display glass to fix a different display segment problem and it worked perfect. I also installed the voltage regulator 91v zener diode to hopefully lengthen the life of the displays. After that it worked great for about 2 months, although I really didn't play it that much. At that time the player 1 and 2 (top) displays started losing segment F. The segment would be missing sometimes and flicker sometimes. A few days later I was losing segment A, then E, then D, then G, then comma. I did the multimeter test for the UDN7180 recommended online(see below) and all legs passed. I also temporarily reinstalled the 100v Zener diodes with no luck. Next I turned on the game and tested frequency with my multimeter at the incoming pins of the UDN and outgoing pins and noticed that for the specific legs that controlled the segments that were out, there was no outgoing signal. The input signal seemed fine. I compared my tests with other UDN chips for segments that were working fine and there were incoming and outgoing signals. This is when I concluded that my UDN7180 was shot. I proceded to replace the suspect UDN7180 for those segments but it didn't fix my problem. Now i dont know where to look next. Any advice would be great. Thank you very much!!

-Tom


These are the tests I referred to from the Internet:

Testing the UDN7180/UDN6118 Chips and Score Glass for Shorts.
Both UDN chips are 18 pin chips. The four corner pins of the chips do *not* need to be tested (pins 1,9,10,18). But all the other pins can be tested. Repeat this test for each of the UDN6118 and UDN7180 chips:
Turn the game off.
Remove the high voltage power supply power connector (3J5 or 3J2, depending on which power supply the game has).
Put the DMM on the *diode* setting.
Connect the red DMM lead to ground.
Put the black DMM lead on each UDN pin 2 to pin 8.
A reading of .5 to .7 should be seen.
Put the black DMM lead on each UDN pin 11 to 17.
a NULL (no) reading should be seen!
Note if the display glass itself is shorted (it does happen!), it MAY show up when testing the UDN pins 11 to 17.
So how do we isolate the problem to the UDN chip or the display glass? First test the UDN chip. If any of the pins (but mainly pins 11 to 17) fail the test, desolder the suspect UDN chip from the master display board WITHOUT DAMAGING IT (these chips are expensive, and if it's good it would be nice to save the chip from desoldering damage). Install an 18 pin socket for the chip, and buzz out the socket making sure there are no shorts, and all traces connect to the socket.
Now again use the DMM and repeat the above UDN test procedure ON THE SOCKET (no chip installed). That is, with the DMM on diode function and the red DMM lead connected to ground, test pins 11 to 17 of the SOCKET with the black DMM lead. Again, a null reading should be seen. If a null reading is seen, the UDN chip has failed and needs to be replaced. If a null reading is *not* seen, chances are really good that the score display glass itself is shorted.
If the score display glass fails the test, it will need to be replaced (there is no way to fix it). After the score displayglass is removed (and before the new glass is installed), put the UDN chip in the newly installed socket and retest the chip as described above.
 
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