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Another Craigslist pickup. This one originally popped up for $3500 and non-working in September 2011. I threw an off for $2000 and figured I'd see where that went. The following day I sent a follow up email and the owner said I could have it. I broke it to the wife (who wasn't too happy), hit the bank, and was off to pick it up.
The following day I unloaded it from the car and decided to see what was wrong with my new game. I checked the boards in the backbox for any obvious signs of failure like burnt and disconnected connectors, blown fuses, etc. I lifted the playfield and checked to ensure the transformer and all under-playfield wiring was connected, as well as the coil resistance. Everything checked out OK so it was now time to attempt powering the game on.
Upon power up I noticed a fairly loud humming/buzzing sound coming from under the playfield for maybe a second or two and then the circuit tripped. I immediately unplugged the game, reset the breaker, and then began to notice smoke rising from under the playfield near the right flipper. I lifted the playfield and followed the smoke back to the power box that house the on/off switch used to turn the game on. I removed the box and found that the thermistor that connected the fuse to the line filter blew. I also noticed that whoever worked on this game before bypassed the fuse as well (I wonder if this is what ultimately caused my problem... keep reading!).
A new fuse holder, thermistors, and varistors were ordered. The game is a re-import but the person I purchaed the game from told me that they had it in the house for 5+ years. I still confirmed that the 220V to 120V power conversion was done correctly (which in fact it was correct).
My plan of attack was as follows:
- fixing the fuse holder and put in an 8A fuse
- replacing the varistor and thermistor
- disconnecting the transformer and then powering on
If it powers up w/o blowing the line fuse I would then:
- turn the game off and disconnect the connectors going to the boards from the transformer
- plug the line assembly box to the transformer and then power on
I hoped that this would determine if the problem was with the transformer or the line filter.
When the parts finally arrive I replaced the fuse holder, thermistor, and varistor. I plugged the power assembly in outside the game while I had it on my test bench and everything looked good (120V AC).
I plugged the transformer up and disconnected all connectors going to the pcbs. When I plugged it in the 8 amp fuse in the power assembly box blew. Looks like a transformer issue.
I had a Judge Dredd game that improperly had a 5610-12835-00 transformer in it (TZ uses 18VAC to power the sound board while later games, like JD, use 12VAC). I pulled that transformer and put it on my test bench. I replaced the 8 amp line fuse, crossed my fingers, and powered it up... no blown fuse. I moved it from the test bench and into the game, reconnected everything, and powered it on.
It resets and the DMD has vertical lines, but it is now showing signs of life.
Now to start troubleshooting these new issues. Luckily these issues are fairly common and fixes have been documented well on the internet.
The lines on the DMD are generally caused by flaky connections on the Dot Matrix Controller board. With the game off, I reseated all ribbon cables on this board and when I powered the game back on the lines were gone.
The reset issue is generally caused by a drop in the +5V on the Power Driver board. The problem areas are J101 and BR2 and its associated capacitors at C7 and C8.
I replaced the male connector at J101, as well as BR2 and caps C7 and C8. There is also a wire jumper mod that can ensure that the proper voltages get where they are needed on the Power Driver board. I figured I would add these since I already had the board out.
Here are the Power Driver board jumper instructions (Originally from Marvin3m/PinRepair.com):
BR2 to C5: two jumpers. Jumper the positive lead of bridge BR2 to the positive lead of C5. Repeat for the negative leads also.
BR1: ONE jumper. Jumper the AC lead of BR1 (just below the positive lead) to connector J101 pin 7.
C6/C7: jumper the two positive leads of capacitors C6 and C7 together (this also jumpers also helps BR1).
BR3: three jumpers. Jumper the lower AC lead of BR3 (just below the positive lead) to connector J104 pin 1. Jumper the other upper AC lead (to the left of the positive lead) to connector J104 pin 2. Jumper the positive lead of BR3 to the large solenoid fuse trace about 2" below the bridge (see picture below).
BR4: three jumpers: Jumper the negative lead of BR4 to the negative lead of C11. Jumper the AC lead of BR4 (just above the negative lead) to connector J102 pin 1. Jumper the other lower AC lead of BR4 (just below the positive lead) to connector J104 pin 4.
BR5 to C30: two jumpers: Jumper the positive lead of BR5 to the positive lead of C30. Repeat for the negative leads also.
With the Power Driver board upgraded it was time to see if I can get the game to power on and stay on. I reinstalled the board, checked all connections once again, and powered it on. Viola! It was working like a champ.
Next I decided to focus on the cosmetics as the game was pretty dirty and definitely in need of a shop-out..
The game was reassembled and was working for the most part.
The upper left flipper was weak - never looked into it much after reassembling, just lived with it.
The game suffered from random resets which was common. I purchased Kahr WPC Power Fix board (kahr.us) which solved the reset issues.
I added gumballs (colored marbles) to the gumball machine; Purely aesthetics.
Clock opto board had failed opto. I purchased a replacement board and installed which fixed the issue
Some 15 years passed and I started to get back into pinballs again. I decided to start going through my pins and get them all working 100%.
I started with the weak upper left flipper. After some research it was suggested that the cause was due to the flipper opto boards the flipper buttons use. Simplest solution was to check solder on header pins, reflow, and clean the optos with a Q-tip and rubbing alcohol all of which did not make much of a difference. Then a suggestion from the 'Pinball Repair' group on Facebook said to swap the opto boards with one another and see if the problem followed the board -- it did. I was able to order some replacement opto boards from dabbler51 on eBay. I replaced both boards and the left flipper was strong again.
Then I watched some Chris Hibbler videos on YouTube and read the PinWiki guides and decided to address the CPU and Driver boards. Replaced the header pins and connectors as well as prone to failure capacitors on the Driver board. I also replaced header pins J210, watchdog U10, and removed U8 RAM chip and installed a 28 pin socket with NVRAM on the CPU board. I ran into an issue afterwards where the CPU board would not boot and thought I messed up a trace somewhere even though I was super careful doing it (and I just successfully completed the same work on my IJ 30 minutes prior). I tested continuity from the RAM socket at U8 to the ASIC, ROM, and processor (and between those chips to each other as well) -- All tested good. Then I pulled and reseated the ASIC. After scratching my head after all of the continuity tests passed, I figured I re-install the board and hope that reseating the ASIC fixed it. Sure enough, the game booted and played just fine. Whew!
One of the drawbacks of installing NVRAM in a TZ is that the system time is used to set the physical Clock in the game. With the NVRAM installed, there is nothing powering the RealTimeClock in the ASIC. That's fine though, I can deal with an incorrect clock over batteries leaking.
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