Tz switch problem

[pinball god]

Was enjoying a game when the gum ball wouldn't fire out a ball. Turn off and on and errors happened. I have reporting switches 81,83,87 and clock is broken. Testing the clock some optos are on but I don't think this is the problem.

Switch test and I see switches 72-76,81,83-85 are on. If I activate switches 73,75,76 which are easy to get to they work fine. Switch 74 won't work. Also found switches 17,27,37,67,77 don't register when pressed but 47 does.

I thought if there is a wiring problem on the CPU whole rows or columns go, in this case one or two switches work

Am I looking at a shorted switch problem or diode issue or more a CPU chip cooked or is it something I am not looking at?

[pinball god]

Forgot to mention I hard wired the power ball opto at the ball entrance a few games prior as I got sick of the thing not working. I was mindful of how close the solder points of the two wires were and was sure they weren't touching but hey maybe they are now??? It did work great prior for say 20 games

[robm]

Is U20 on the CPU socketed - if so, it might be easiest to replace this first - they often show symptoms just like you are describing. Its a ULN2803 IC.

As for the clock, i've got a tester where i can test each of the opto's individually, but you would need to send the board to me.  I've got one spare TZ clock board coming from Ingo, let me know if you are interested.  His boards are top quality and use readily available optos (the original ones are near impossible and hideously expensive if you can find them) - plus they can use colour changing LEDs!

[pinball god]

I replaced the cpu pcb with another and I get gumball entry error and clock broken. again in the switch edge test I have 72-76 and 81,83-85. I do recall getting the gumball error first off in the entry.

any ideas

[Steevsee]

Looks like all the optic switches, except the clock, which normally show up in edge test.

Only other opto not sensed is 87 (gumball entry)

Can you get this switch to register.

Maybe just a bad  led in the switch.

[Steevsee]

Also does switch 24 show in the switch edge test as this switch should be always closed?

As far as the clock goes, these switches are all  connected to an extra board and may be worth checking the connector at J5.

[robm]

So if you swapped the CPU, we can prob assume its a wiring issue, not board related.

If its multiple switches out, it also could be the opto board under the playfield (i think its a 10 opto on TZ) - the LM339s can go on this one as well causing a few issues.  Again, if you had another game with this board you could swap them and it would eliminate this as the cause or not quickly.

Otherwise, clean all the optos with a toothbrush to make sure there is no dust, and inspect the wiring looping from each one to see if there are any shorts

[pinball god]

Also does switch 24 show in the switch edge test as this switch should be always closed?

As far as the clock goes, these switches are all  connected to an extra board and may be worth checking the connector at J5.

yep 24 shows up but I didn't think of mentioning it. cant get 87 to register out of all the optos. I have a spare opto pcb but not sure it works. I soldered sockets for these chips but I don't think well. I had the old fuse error problem, so bought a aftermarket from great plains that has leds to show the status of optos. at the moment 2 are flashing on/off continually.

[pinball god]

Update to help others if they experience anything similar. Problem solved.

I disconnected the 10 opto board and the cock worked ok again. While reconnecting the main plug back to the opto pbc I noticed a wire from a target dangling by itself. It was the same colour as in the string of switches that were out. Reconnect and all good

[Steevsee]

Nice work and thanks for sharing your solution.

[pinball god]

Pleasure stevesee

I just quickly read my post and I noticed a bad typo. I've spoken to my wife and I don't have a cock problem  .

Using electronic tablets and typing can be hit and miss. The TZ clock not cock was not working. I don't know why the broken wire had such an effect on it though.

[Steevsee]

...I disconnected the 10 opto board and the cock worked ok again.

Pinball repair CAN be guite exciting, but you may be going a bit far!

Never even noticed the typo, to be honest, but it's a good one.