I rarely like to admit defeat but I have to say I am pretty irritated with my twilight zone. I have clock problems and I have encountered clock problems before but not like this. Here is where I am at:

The clock did not work on the game when I got it although it had a new rotten dog board in it. I took the clock apart to access the optos on it and went into the test menu. Some of the opts were not working so I figured easy fix, swap it with a new board. Same result. So at this point I figured I rebuilt the clock wrong and took it back apart. Rebuilt the clock again, hooked it up with the playfield in the upright position from under the playfield, clock works great. Unplug everything and mount it on the topside, put the playfield down and turn the game on, clock error. SOB. Take the clock off again, second guess my assembly and do it all over yet again, install with playfield up works great, move on to the full install, drop the playfield down and clock error.

At this point I start checking all ribbon cables, the clock harness, all connections on the opto board, connections to cpu, basically double check all wires involved. No change. So I decide time to go to the shop, grab another clock from a tz that I know works. Swap it into the game with the playfield up from the underside of the game, clock works great. Install it on the topside, clock shows bad. Now if either of these clocks are installed on the topside and I raise the playfield up, they both work great then too. So there has to be something going on when the playfield is lowered that I just don't see. I have ensured that no harnesses are being pulled when the playfield goes down. The only thing I have not done yet is replace the opto board on the bottom of the playfield, maybe there is a cold soldier joint, replace the rom chip in the cpu or swap the cpu all together.

Some background:
I have rebuilt maybe 20 clocks over the years, I am not an expert but I am familiar with them.

I made sure the teeth are lined up as well as the line for the black gear.

Checked all continuity of the clock wiring harness. I also even swapped the harness with the second clock harness to see if it would make a difference and no change.

Have had switch test open with the playfield raised up, watched all switches and lowered the playfield, no switches activate or deactivate when the playfield gets lowered.

So if anyone has experienced this please let me know what I can do to remedy this issue. It is driving me nuts. Also if anyone can think of anything that I have overlooked please let me know. I did order a replacement board from INGO in germany and will have it hopefully soon.

Thanks for any help.

Zaza, not a bad guess but it happens with and with out the light on as well as my house and the previous owners home.

Jgaltr56, I am thinking pinched wire too, but with the switch matrix on the screen the game has no switch changes registered when the playfield gets moved. So if it was a pinched wire I would think the opto would show itself closed or open depending on its normal position.

Thanks for the thoughts so far everyone

I'll give this a shot today. Does it need to extend further that the current hand does or same length where the hand currently is.

Chris, you were dead on. For some reason I have not had this issue pop up on a few other rotten dog boards in the past but it did this time and the heat shrink solved the problem. I spent 4 hours rebuilding these clocks, swapping harnesses, changing out gears, etc and in about 1 minute your trick fixed my issue.

I'd like to thank everyone for commenting and taking the time to read about my issue. Threads like this are why I still stick around Pinside in a time of such negativity. I hope that negativity doesn't push so many of the great assets on this site because with out them Pinside would never last. A donation has just been made on behalf of this thread, thank you guys for getting this figured out.

Happy 4th!

Hey Everyone,
So I was hoping this was resolved but running into the same damn issue. Works underneath the game, not on top. I have attempted to redo the heat shrink, double it up, make it longer, shorter, etc. On the bottom side of the playfield when it works, I can hold the clock in literally any position, face down, face up, sideways doesn't matter it still works hooked up on the bottom of the playfield. In clock test it seems as though its the hour optos are whats messed up but I can't be sure. I have pulled on the harnesses, manipulated the direction they are and anything I could think of to see if its a connector issue. I also even considered that the leds in the game were too bright and causing interference with the optos, so I disconnected all GI in the playfield and the backbox. I just don't know what else to attempt.

Any help is greatly appreciated.

This is the thought process I have had and I have attempted to vet out a few of the issues. I did meter all my connections for the clock harness, they came out fine but just to be sure, I swapped the harness with another clock harness to no change. I attempted to manipulate the wires a lot to see if it was a loose or intermittent connection, which I still think it is but I can not get any change in the switch matrix no matter what I do to the wires, there never seems to be a switch change when pulling, bending and straightening the wires.

I had the clock plugged in through the playfield and attempted to test the clock in every imaginable way to see if the clock would work through the playfield and no change.

I am pretty stumped. At this point the only thing I can think of is the opto driver board may be flaky?

Sorry I wasn't very clear. I was thinking it was the opto board mounted on the bottom of the playfield. Is that a possibility?

Ugh, I was hoping that was my culprit but atleast you saved me the hassle from swapping it out. What's driving me crazy is that even with swapping the clock harnesses it doesn't work. It points to the harness going to the 8 driver board in the backbox. Problem is they all meter out.