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Twilight Zone Trouble

thecroquetkid

thecroquetkid

Site Supporter
2 10 Years
Joined
Jul 4, 2013
Messages
90
Location
The Twilight Zone Scarborough
My TZ kept resetting during a game, particularly when operating both flippers together. Having read pinwiki, I reseated all the connectors and tightened all the earths. YES, problem solved. I had a game with no reset problem.

I was very pleased with myself, but noticed that a bulb was out under the left slingshot. So I switched off, went under the bonnet, and replaced the bulb. Then switched on to find that it was still not lit. Don't worry too much, I thought. Just play it with one bulb out!

FORGETTING TO TURN THE PIN OFF, (IDIOT!!) I screwed the bulb holder back in. While I was doing that the game reset.
( Have I shorted something?) I then noticed 3 more bulbs out on the left hand side under the left outlane plastic. These look like they are daisy chained from the original offending bulb.

I started a game and the 3 pop bumpers, 2 slingshots and left inlane rollovers (switches for right spiral and slot machine) are not working. The solenoids stated are not working in game but DO work in solenoid test. I do have a manual, but most of it is above my head. But I did notice that the switches for the features not working are all on column 3 of the switch matrix.

So, I may have a switch matrix problem, but don't know what to do about it. I've visually checked fuses. They all look ok.

I'm located in Scarborough. However, I do have a van, so I can take it elsewhere for diagnosis and repair.
 
You really need to check fuses with a test meter. You also need to pull one end of the fuse out of its holder.
However if you have shorted voltage into the switch matrix there is likely to be damage in the matrix.
 
It sounds like you probably shorted the GI string through the switch matrix. If the GI lamps are still out you probably just blew the fuse, change that and you they should work again. As @stoptap said you really need to test the fuses with a meter to know for sure as they don't always look obviously blown.

Use the switch edges test to check out all of the switches in column 3. If the wiring is intact and none of them work then you've definitely damaged the board. Most of the time this will have damaged the ULN2803 at U20. If you have a logic probe or a scope then you can probe each of the column outputs to prove this theory. No pulsing = bad chip. If you can solder then its an easy repair, just socket the chip when you replace it so its an even easier fix if it happens again in the future. Its possible you may have damaged chips further back on the board but most of the time it will just be U20. If you don't feel confident doing this then there's plenty of people on here who offer a board repair service.
 
As said, check the relevant fuses.

Make sure that there is no visible short (loose wire, solder splat) where you were screwing before you power up

The dead light could be corrosion on the bulb holder. Scraping with a screwdriver might sort it after you have replaced the blown fuse and checked for a short. Ideally you would replace the bulb holder, but ideally I would not be a fat bald ****.

Then go into switch test to see which switches are dead to see if there is a specific row or column that is out. Look for a pattern and revert back to us. The manual has a switch matrix in it. You have probably put gi (light bulb) voltage down the switch matrix and fried a chip

Have you done board repairs before ?

If you have not done much soldering, have a serious think before you start messing with the mpu board.

This sounds like a relatively simple, inexpensive fix at the moment. No need to move your game, you could mail the mpu board to a repairer. A few guys on here could fix a blown chip for you. You will probably do less collaretal damage by carefully removing a board than by carefully moving your whole game.

When you remove the mpu boatd (bottom left board) take photos of all the connectors before you remove them, in case wires snap off. This would be unlucky, but it does happen. Label each connector with a fine permanent marker so you can double check where they go when you put them back, the numbers are written on the green circuit board.

In thevgrand scheme of pinball repairs, this sounds quite minor as of now.

Good luck
 
Thank you for your replies. Much appreciated.

1. I have swung out all the fuses and checked them for continuity. No bad fuses.

2. Having referred to the switch matrix in the manual, it's the whole of column 3 that is out. In switch edge test, I take it that you activate the switch with your finger and listen for a beep or see the square change colour? All of column 3 is not working in this test. The solenoids in this same column ( 3 pops and 2 slingshots) work ok in the solenoid test, but the switches on them do not work, I deduce. The manual says this column is related to J206-3 and U20 -16. So it looks like U20 has blown (no visible signs though). You guys are good!

3. The lower left playfield GI is out when doing a GI test and after a good read of the manual I have found a brown wire off J121-1 on the IDC connector. This needs putting back in. There is no burning.I can see that two blades cut into the insulation as the wire is inserted. Is there a technique or tool for pushing it in there neatly?

4. I do have a Williams Indy, so I could swap boards? I have not done this before. Is it just the ROM chip that has to be swapped as well? I think I would rather send the board for repair than risk Indy, which is behaving impeccably! I don't do board repairs! chris b, do you ?
 
1. No bad fuses is a good thing. :thumbs:
2. Yes providing you have continuity between J206-3 and the switches then you've almost certainly blown the chip at U20. There won't be any visible signs, it just won't work.
3. Sounds like you found the problem with the GI then, nice work. :thumbs:Ideally you should use a proper IDC tool to punch down the cable back down in to the connector like this: http://pinparts.co.uk/products/idc-insertion-tool-0156-for-pitch-connectors If you're careful in a pinch you can can use a small flat head screwdriver to get it working again and improve it later if required with the proper tool. No doubt somebody will be along to talk about the benefits of upgrading to trifurcon connectors but it probably isn't necessary for home use, especially if you use LEDs.
4. Yes Indy and TZ share the same MPU so you can swap the boards over if you like. Indeed it is also only the ROM chip that needs to be swapped and you're good to go. Be aware though that if you swap the ROMs then you will lose your high scores and settings etc. The legs can also snap easily if you don't remove the chips evenly. There is a tool for doing this properly too, something like this http://www.ebay.co.uk/itm/Chip-Extr...149625?hash=item4d533f75b9:g:D~QAAOSw5cNYhApd If you really want to change the chips over before you can get a proper tool then you can remove them with a small screwdriver although it does carry some risk. Ideally you'll want to use 2, one at either end of the chip and lever gently and evenly. If you don't have 2 screwdrivers of a suitable size then you can use 1 but working each end a very small amount at a time. They push in a lot more easily, just make sure all of the legs are lined up properly before pushing them home, especially if you bend them during extraction!
 
When you push the wire back into the IDC connector for your GI make sure you remove the connector from the board. Don't try and push the wire in with the connector in situ or it will flex the board badly.
Unplug it and rest the connector on the wood of the inside of the backbox and keep your hands as far away as possible from the screwdriver blade.
 
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stoptap said:
Sweet. Nice to meet you Graham and glad it was a trouble free fix.
Click to expand...
Hi Stoptap,
Could you kindly share the resolution with me? My TZ is having the same issue with J206-3/U20-16 Green-Orange. (3 pop bumpers/Slings/3 left lower switches. I would ask you to repair my problem, but I live in Oz. Cheers and Thanks, Glenn
 
ozbizz said:
Hi Stoptap,
Could you kindly share the resolution with me? My TZ is having the same issue with J206-3/U20-16 Green-Orange. (3 pop bumpers/Slings/3 left lower switches. I would ask you to repair my problem, but I live in Oz. Cheers and Thanks, Glenn
Click to expand...
It's likely to be U20 on the MPU board. This is a VERY common issue particularly if changing lamps/LEDs with the machine switched on.

Unless someone has been at the board before U20 is likely soldered in so you might need to ask for professional help to fit a socket as the tracks are VERY dodgy on these boards and are damaged easily even when you have great soldering skills and the correct equipment.

Have a read here as this will very likely cover your issues: https://pinwiki.com/wiki/index.php?title=Williams_WPC#MPU_Circuitry_Switch_Matrix_Problem_Diagnosis
 
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ozbizz said:
Hi Stoptap,
Could you kindly share the resolution with me? My TZ is having the same issue with J206-3/U20-16 Green-Orange. (3 pop bumpers/Slings/3 left lower switches. I would ask you to repair my problem, but I live in Oz. Cheers and Thanks, Glenn
Click to expand...
Howdy Glenn.
As Homepin said it needed the ULN2803 at U20 changing. As ever when replacing chips it is good practice to solder a socket onto the board then if it ever needs replacing again it is a simple job to put in a new one.
 
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