Wednesday, July 23, 2008

Twilight Zone clock repaired

Last week I finally repaired the clock of my Twilight Zone pinball machine.
Nothing special you say ? Well it is for me !

Believe it or not but I have this game for 7 years now.
Bought it with a broken clock.. shopped it many years ago, even took pictures on how to disassemble the clock.. but at that time I didn't have the correct optos.

Later I ordered the correct optocouplers, but didn't install them as I had work on other games.. just threw the optos in the coin box of TZ and forget about them.
I even found the invoice - paid 600bfr (= 15 euro, 20 us$) for 2 optos at the distributor in Brussels).

Now finally I decided to work on that game. Installed the optos I had, they didn't work - turns out these were for the minute hands of the clock, and the optos for the hours are of a different type.

Desoldered the optos again (woosh, there's $20 down the drain as I had cut the legs already short so those desoldered optos can't be reused for the minutes-board)

I remembered reading on rgp somthing about installing optos backwards to have it work. So I tried another type of opto, didn't solder it yet, just held it in place and connected the board and went into the clock test mode.
Tried it, and yes, when I inserted the opto backwards in the pcb it worked. Nice !

Soldered the optos back in.. assembled the clock, but didn't notice the orientation and put in the board upside down in the clock housing, so the connectors didn't match. Aargh. It really was time to go to bed.. but I wanted to finish it.
Disassembled the clock again.. oops.. the small c-clip that holds the minute hand of the clock fell onto the ground. Aaaaargh.. I really should be sleeping already..

As we have a stonecarpet floor, you can imagine retrieving a small metal c-clip is an impossible task.
It's not the first time I drop a screw or other metal piece, I have a big magnet to sweep over the floor.. a few minutes later I had found it.

Assembled the clock again, and tested it.
The good news was that the repaired optos worked, bad news was that another one was registering all the time because of the vibration of the motor.

Time to go to bed.

Next day I disassembled the clock again (and didn't lose any c-clips this time :)
re-soldered pins that make the connection between the two boards, assembled the clock again for the dozenth time, and finally, my Twilight Zone pinball machine works like it should ! No more credit dot !

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