One of the clients I service in at my job is a CNC shop.

I was sent to fix one of their CNC routers one day and saw they had 2 pinball machines in the back of the shop. Both were semi functional. The owners of the shop were amazed that I knew anything about them, let alone how to repair them (little did they know). Over the years we struck up a deal of sorts; I'd maintain their machines (CNC & Pinball) and they would give me a corner of the shop to restore Pinballs and let me use their pro downdraft spray booth for clear coating.

This of course has led them to buy a dozen or so pins.

They called to tell me that they bought a mint Williams Time Warp, that had been in a guy's house for 20 years. Time Warp is a really great game and it was one of only 2 Williams games with curved flippers, thus it is rather collectable.

Everything worked on it!

That is, until they got it to the shop. Now every coil locked on upon power up!

The following is a step by step guide to the repair; and required bulletproofing that applies to all Sys6 (and much of Sys3-7).

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Deeper into the guide:

FIREPROOFING SYSTEM 3-11 GAMES (p2)

BULLETPROOFING THE POWER SUPPLY (p2)

CRACKED SOLDER JOINTS - EVERY GAME HAS THEM (p2)

UPDATING SYSTEM 3-6 BOARDS INTO SYSTEM 7 (p3)

I MIXED UP THE BLACK AND WHITE PLAYFIELD CONNECTORS - WHAT CHIPS DID I KILL? (p6)

Probably by now you have heard someone say "reseat the chips" that might fix it.

Then someone posts, that indeed, now the game is "fixed".

Of course, that "fix" is only temporary.

What it really tells you is that the sockets are defective and need to be replaced.

With the game running, if you can twist the chip in the socket and cause the game to lock up, or displays to go nuts, those sockets HAVE to go.

The worst offender in crappy chip sockets is SCANBE. Total crap. Those sockets hold the chip legs by the edge, for the least contact surface possible. It would be hard to think of a worse design.

ALL SCANBE SOCKETS ON BOTH WILLIAMS AND BALLY MUST BE REPLACED - ALWAYS.

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RN sockets are a little better, but still not very good.

If you can pull a chip out of a RN socket with your fingers, it's got to be replaced.

A good socket needs a flat screwdriver or a chip puller to lift the IC, that's how tight it SHOULD be.

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If you are new to working on circuits, it might seem like a difficult task to remove a 40 pin socket, but like most things in life - there is a trick.

Carefully pry off the plastic frame, leaving the contacts behind.

Then heat each contact up with a soldering iron and pull them out with needle nose pliers.

(Of course if you have a solder sucker like a Hakko or a Metcal, you can remove the whole 40 pin socket with the plastic frame still attached)

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Uggg, fncking Scanbe....

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Harder to see before you tear into things, but look at what these RN sockets were hiding - gold sockets!

Gold sockets sound like a good idea (hey, gold is expensive, and it never tarnishes right?) but usually gold plated sockets have less tension than tin sockets. This is why you can often pull the ICs right out by hand.

Gold sockets for gold IC pins = good idea.

Gold sockets for tin IC pins = not so good idea.

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Once you have all the socket pins pulled, check the condition of the board.

The green conformal coatings on circuit boards is resistive to solder.

When you solder in the new sockets, be careful not to bridge any solder into chips in the green coating.

If you repair lots of boards, you can get touch up coating in a pen:

http://www.productionsupplysolutions.com/Green-Overcoat-Pen-p/4190-gp.htm

If you seldom do repairs, clear nail polish works nicely too.

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The "acid" in Alkaline batteries probably has killed more pinball machines than any other single cause (other than back in the 80s when operators just took them to the dump).

Note here that someone took the time to replace the battery holder, but left the cancer of corrosion to eat away at the surrounding circuits.

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That 5A-9247 chip is really just a 50 cent 74LS02, so we cut it and the .01 uf capacitor out.

Why not just "clean" off the corrosion? Because we can't clean the back of the chip legs can we? We can't clean what we can't reach.

We can't bulletproof a game if we leave corrosion eating up our board.

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Use your solder sucker tool to clean out the holes. Usually it will just lift the IC leg remnant out with the solder, but if not you can poke it out from the backside.

A steel safety pin or a wooden toothpick can be used to clean out a stubborn hole; both are resistive to molten solder.

Don't press hard, or you might push out the whole plated tube that connects the top and bottom board pads. Let the solder sucker do the work.

If the pad is so corroded that the solder won't melt, just add some fresh solder. The flux will clean and help with the heat transfer.

Now clean 100% of the corrosion from the board.

You can use a brass PC board brush, 400 grit sandpaper, soda or wheat blasting. There are too many ways to describe them all here, but whatever you do, just make sure you get ALL the corrosion. I expect most pros are using wheat blasting and most amateurs are using a brass brush.

After physically removing the corrosion, we chemically neutralize any invisible remnants with toothbrush and SnoBol.

SnoBol "Thick" toilet cleaner is an excellent acid that won't run all over the board. It will quickly dissolve alkali corrosion. Don't leave it on too long or it will dissolve the copper circuit traces themselves.

The SnoBol (acid) is the chemical opposite of the alkali (base). It works about 20x faster than vinegar or mustard.

After neutralizing the alkali corrosion, we clean off the acid with Distilled Water followed by Isopropyl Alcohol.

I know it's tempting to just remove corroded blank pads from the one side of the board, but try to just clean them instead.

If the solder readily sticks to the cleaned traces, you know you did a good job cleaning off the alkali. The act of putting a new layer of solder over the cleaned copper traces is called "tinning the traces".

After soldering on your new sockets, paint over the formerly corroded traces and pads with your green touch up pen, or clear nail polish. This will seal out any further corrosion.

Obviously, cut the battery holder off the board and install a new one remotely!

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With all these sockets that need replacing (and any IC we replace we ALWAYS use a socket, even if Williams did not), we need an extremely good socket.

The best sockets for our use are .1" (2.54mm) spacing SIP strips.

Why strips instead of conventional sockets?

1. Strips let us see all sides of our solder work. The original boards were float soldered, an option we don't have for repair work. We might even have to do a quick touch up on the component side of the circuit board. You can't do touch up work on the inside of a conventional socket.

2. SIPs just snap to whatever length we need. No sense stocking 11 different sockets, when the SIPs can become any size we need.

3. SIPs have excellent "machine pin" sockets that really grip the IC pins. All sides make contact. 10.jpg

Of course the SIPs can't be perfect.

If we solder them without some structure, they might end up leaning in one direction or another.

Use an old chip, or even another socket to keep the pair of SIPs parallel to each other and facing straight up.

From the back side of the PC board, solder the 2 end pins of the sockets to hold the SIP in place. Then you can remove the old chip and use it to line up the next row of SIPs.

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We do ALL of our soldering from the back side (non component side) of the PC board.

I'm not going to turn this into a soldering tutorial, but I'll run you through the routine.

Turn your iron up hotter than normal because the end pins often have to be soldered into the large ground plane traces, and these act as big heat sinks. I run at 480° F, but if you are a beginner, use a lower temp until you know what you are doing.

Do all the thick ground plane and power plane traces first, with your hotter temp.

Press the iron firmly against the solder pad AND pin of the socket. Wait half a second after you see the pad face turn to liquid and then add your solder. Watch, the moment you see the solder puddle shrink for a second, move the heat to the next pad. When the puddle shrinks, the solder has flowed to the other side of the board. Go ahead and check. See how you just soldered both sides of the board at once? Nice job!

Once the heavy plane traces are done, lower your soldering iron temp and hit all the rest of the pins on the SIPs.

Check your work on the component side of the board and make sure each SIP pin is soldered on both sides. If you have to touch up a solder joint on the component side, you are going to be VERY thankful you used SIPs rather than closed sockets!

Use your meter set on the continuity mode (beep mode), and check EVERY socket pin to the place it runs to on the board. Don't take a shortcut here. Do every one.

Also check each adjoining socket pin against the next to make sure you did not accidentally make a solder bridge.

Clean the flux left from the solder with isopropyl alcohol and an old toothbrush. I know, you probably don't have to, but it is the sign of professional work.

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Besides junky IC sockets, EVERY System6 board needs the big 40 pin socket replaced. Even back in the 80s, the female sides were already often bad).

The tension on the connectors Williams chose was often bad from the start. In addition Williams had data flowing through those connectors, so the tiniest loss of connection would lock the whole game up.

Those connectors were designed for 25 installation cycles - after 40 years, that duty cycle has been greatly exceeded.

Looking closely, you will see connections that have lost their tension, connectors that have simply broken off and just plain ol' corrosion.

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There is no way around it, go to Great Plains and order new connectors :

https://www.greatplainselectronics.com/products.asp?cat=82

Buying $8 worth of connectors will save you $50 in melted coils.

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The 40 pin connectors look like a big job to remove, but again, there is an easy trick.

Using a utility razor knife, cut each soft plastic socket apart from the rest of the group. Just push straight down. Now you can pull each cell of plastic away, leaving only the contacts.

Remove the contacts with needle nose pliers and your soldering iron.

The end pairs of contacts are soldered into a large ground plane trace, you might have to turn up the iron heat to get these out cleanly.

Of course, if you have a powered solder sucker like a Metcal or Hakko, you don't even have to cut up the connector. It will just fall out from the back side.

https://www.greatplainselectronics.com/products.asp?cat=82
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These 3 watt 27 ohm resistors are still working, but really need to be changed out with 5 watt power resistors. Don't forget to leave a lot of room under them for air flow. I like to leave 3/8" between the new resistors and the circuit board.

Or, if you want to, you can replace the 8 TIP42 lamp matrix transistors (Q63, 65, 67, 69, 71,73, 75 and Q77) with IRF9Z34N MOSFETs. The MOSFETs need so little current, than you can just replace the 27 ohm resistors with wire jumpers. At $1 each, not a bad mod:

http://www.greatplainselectronics.com/Category-106.asp

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Also, you might want to cover converting a board from masked PROMS at IC21, 22, 26 etc to using 2716s so you have fewer sockets to replace..

Yes, if you have an EPROM burner, that is a nice way to go.

I go on a case by case basis, but if the connectors are corroded or burnt, they should go for sure.

Resoldering the connector pins on the back of the board is a good idea too. Many times vibration over the years has cracked the solder joints.

I might also add, although obvious; don't bother replacing empty IC sockets - they are not going to hurt anything.

Connect the negative side of the remote battery pack to the upper right ground plane, and the positive side to the lower left old battery pack hole.

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Next section will be Sys6 power supply.

A few of you have emailed me about exactly how to replace the lamp driver transistors.

Start by cutting out the eight TIP42 transistors, and removing the very burnt 27 ohm resistors.

Note how nice and burnt the circuit board is after years of hot resistors and poor electrical design.

Check the traces and make sure they are all still good.

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The new IFR9Z34N MOSFETs are oriented in the same way the old TIP42s were, so just solder them in.

Make some Jumpers out of heavy wire to take the place of the old burnt 27 ohm resistors. I used 16 gauge for this repair, but anything from 16-20 gauge should be plenty.

Again, with all that burnt circuit board area, take the time to make sure every connection has continuity.

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Yep, nice way to go!

If you have solid core wire, you can bend it on those lead benders too - looks great in green.

International Rectifier's full manufacturer part number is : IRF9Z34NPBF

$1 each @ Great Plains Electronics

Indeed!

100s of different brands of ROMs, probably a repair part.

Probably not "best practice" (old damaged parts could fail open) but you are most likely OK.

Next time you service the board, replace them.