Hi All,

I ran the diagnostics on my Time Warp and switches 44, 04, 12, 20, 28, and 36 are reading as closed/stuck. I physically examined each switch and metered them all and all of them are physically open. I did notice that all of these switches are connected to a white wire with a yellow stripe. I traced this wire back to pin 6 on connector 2J3 to the Driver board which is switch row #4.

To diagnose further I unplugged 2J3 and 2J2 and put my meter (resistance test) leads on #6 of 2J3 and #3 of 2J2 to test switch 44 (left inside rollover). When I toggled the switch it did read as the switch opening/closing. To crosscheck I performed the same exact test on a known working switch with the same results. This leads me to believe the problem is on the driver board. I read in another thread that they had a pin on 2J3 shorting to the mounting tab but I checked that and no short was found.

With that being said I suspect the problem to either be in IC15 (TC4049BP) or IC11/PIA II (HD46821P). The problem is I don't know how to test these devices with a multimeter. I tried measuring resistance across the pins associated with Row #4 on IC15 and cross checked them with a good row to see if any values varied but they did not. I’m thinking I’ll need to have the device powered up and test with a probe (don't have one). Does it sound like I should just replace both ICs and call it a day? Thanks!

Thanks for the fast response! I tried the diode test and found nothing shorted. Cross checked with the the other IC with same values appearing.

I am thinking though, since I now know how the 4049 works can I simply power up my game, go to switch test, set multimeter to DC voltage, put the meter leads on the pins across the inverter of the IC, toggle the corresponding switch and cross check on a known working row?

If so would it be incorrect to have the black lead on the ground bus and use the red lead for probing? Just so I don't accidentally touch the two together while testing. Thanks!

UPDATE #1 10/29/14: I got the Elenco LP-560 logic probe and tested the input (pin 9 IC15) and got a low reading and the output (pin 10) was high. This was the opposite of any working row. In addition when I engaged the switch on the working row I got the same reading on it as before but now pulsing. When I engaged a bad row switch (44 left inside rollover switch) I got the same reading on it as before but with no pulse. From here I it seemed like it was the 4049 so I swapped it out but got the same results before the part swap!

From this point I doubted myself and went to go double check from the connectors back to all the switches. I disconnected 2J2 and 2J3 to isolate them away from the driver board. I suspected a short and so I decided to (resistance) test each lead with the white wire w/yellow stripe on every switch to ground and found a short that read as 5.5M ohms. I tested every row 4 switch and they all read this while the other rows did not. It was a bit tricky though as sometimes it appeared to go away intermittently and read as totally open. I rotate tested each switch at the white w/yellow stripe wire point and noticed it would start to read as open again and then I'd test switch 44 (left inside rollover) and it would start to read 5.5M ohms again. From here I desoldered the two white w/yellow striped wires from this switch and I tested each one to ground. One read open and the other read 5.5M ohms. Getting closer now. I noticed that the two white w/yellow strip wires were split with each having 3 devices. The non-shorted to ground wire connected to switches 12, 20, and 28 while the shorted wire was connected to 04, 36, and 44 (itself). At this point I was always suspect of that hard to disconnect plug that goes to the coin box so I unplugged it and restested the wire at switch 44 and 36 and the short was gone! This isolated the short to the right coin switch and so I went to check it out and low and behold the connector lead that was attached to the yellow w/white stripe snapped off and conveniently stuck itself up against the screw plate of the switch. From here I unstuck the broken lead and desoldered the wire from the diode, reconnected the coin door plug and the short was gone. Fired up the game and now only switch 30 is stuck, a success! I should also note the left drop down target bank isn't reading anything so I'll need to check that out. Now on to switch 30 and the left drop down bank...
UPDATE #1 10/30/14: I found out why the left 3 bank drop target wasn't scoring anything. The A-7941 "horseshoe" sliding contact on the middle drop target has one end of the shoe completely snapped off. As far as switch 30 it was quite weird. I tested the switch contact points and found the white wire w/purple stripe was reading resistance differently to ground than other switches. I desoldered the diode from the switch and tested the switch and it was fine. I tested the wires and they seemed like all the other switches so baffled I soldered the two white/purple stripe wires back to the diode and switch fired up the game and found no more stuck switches. My only explanation could possible be that the white/purple stripe wire was up against the kickout mechanism and maybe it shorted out somewhere. To fix this I zip tied the wires to the rest of the little wire trunk running by.
UPDATE #2 12/5/14 I did some more work here and there over the past few weeks and resolved all switch issues. I'm pretty sure the reason why switch 30 was reading as closed from the 10/30/14 update as I ran into the "issue" again when diagnosing the non-scoring 3-bank. I had all the drop targets down (duh!). As far as the 3-bank not scoring it still didn't score after I replaced the horseshoe contact (bought from homepin.com). After comparing the two drop target banks I realized that whoever last worked on the 3-bank forgot to solder back in a jumper wire from one sliding plate/board to the other that connects to the Green/Black stripe switch wire. After putting that jumper in all switch score and none are stuck!