Pinball Diary – Do You Want to Mouse Around?

March 17th, 2010

Tonight, I decided to get into a Mousin’ Around that has been in the shop for a while.  I picked it up from a lady’s garage a year or more ago, and had thought it was pretty nice at the time.  Upon closer examination, the problems started to surface. 

The center moving drop target bank was broken, stuck down,  and  scotch tape covered the hole.   A quick exam showed that the bracket was broken preventing the targets from moving up and down smoothly.  My partner Bob and I have been fixing games for about 20 years, and I have learned over the years to trust his wisdom in repairing all things mechanical.  So off with Bob the target bank mech went for repair. 

Next we examined the playfield in more detail.  The lane diverter at the very back did not work – it was stuck under the plastic ramp.  Whoever worked on this last apparently reassembled the playfield incorrectly.  I made a mental note to look closer at that once the playfield is out. 

We started to pull the plastics off in preparation for cleaning.  Of course, half of the screws must have been lock-tited in, so we ended up breaking off the heads of the bolts.  A couple os screws stripped so bad, we had to clamp a vise grip pliar on them and twist them off!  Once the heads were broken off, it was a simple matter to knock the tee-nuts out by hammering the broken bolts from the top of the playfield and install new tee nuts and bolts.

Getting the ramps out was easier than it first looked – a nice design by the Bally team!  Once the playfield was stripped, we pulled it out and turned it upside down to get to the bottom.  Upon close inspection, we located at least ten broken wires, mostly on general illumination, but also on the right kicker.  Two of thelamp sockets for two of the pop bumpers were missing.  Not sure whay someone would take them out?  Did they have problems in this circuit and cut them out to eliminate a problem?  Not sure, but we followed our policy of righting every hack the previous mechanic created and put the pin back to factory.  We would just trouble-shoot any lighting problems that might arise from doing so.

Also, Bob took a look at the diverter mechanism which was now free from the ramp which had previously jammed it.  The ramp was not switching from out to in with each pulse of the coil as it should.  Bob dissembled it and found the odd-shaped plastic that makes it rotate back and forth was thick with hardened grease.  A quick clean and reassembly and all was back to normal.  Once finished on bottom, we replaced the playfield in the game and started the cleaning process. 

A thorough cleaning and waxing of the playfield, cleaning of all plastics and ramps with Novus, installation of a box of 89’s and three or four boxes of 47’s, and we were ready to reassemble.

Reassembly went fairly quickly, and it was time for the “smoke test” – you know, when you give the pin a chance to let its smoke out?  This is where we see if the new pop bumper light suddenly get VERY bright or VERY dim and then the smoke appears.  Fortunately, no drama appeared, and we played a few test games to assess what further work would be required.

The list was fairly short – a new battery holder on the MPU, which showed heavy corrosion, a burned GI edge connector, the right 16 digit alpha-numeric display was completely dead, and the cabinet and legs would need some serious cosmetic attention.  Oh well, the shop is a disaster of scattered tools, dirty paper towels, old rubber rings, burned and blackened light bulbs, and it was midnight.  Sufficient unto each days its evil!  Tomorrow is another day.

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Troubleshooting a Dr Dude 16 digit alphanumeric display

October 29th, 2009

I learned a valuable lesson yesterday that I thought I would pass on.  I had a Dr Dude pinball whose right display was missing its “g” segment.  Additionally, the entire glass was a little weak until warmed up.  I debated as to whether the “g” problem was due to a bad glass or a board problem but since the glass was weak in general, I decided to start by replacing the glass.  Since purchasing my Hakko desoldering station a year or so ago, this task has been made IMMENSELY easier!  If you do any desoldering on circuit boards, a good quality desoldering station is well worth the money, when compared to soldapullit or vacuum bulb type devices.

After replacing the glass, the g segment was still missing.  Took a quick look at the schematic and saw that the 7180 chip was the most likely culprit.  I pulled the old one out, and unfortunately lost a trace or two despite taking my time.  I have learned these things happen no matter how hard you try to avoid them, especially on older boards such as this one.  I installed a socket, double checked all of the traces going to and from the chip, made repairs as necessary, and installed the new 7180.  Unfortunaely, still no g segmant.  Another look at the scematic showed a 4049 chip downstream.  Before pulling that, I checked the other components in the circuit, mainly a couple of resistors, and then went ahead and removed the 4049.  A new socket and chip later and back to the game for testing.  Still no g!  This was getting frustrating!  I decided to go hard core and pulled out my trusty logic probe to see if the chips were getting the proper input signals.  After a half hour or so, I started to formulate the opinion that perhaps my problem was originating on the CPU board.  Still not entirely convinced, I switched out both the 4049 and 7180 chips with new ones in case one was defective from the factory.  No luck.  To confirm my suspicions, I got old school on this pinball!  Put away all of the fancy digital test devices and got out a good old pair of alligator clips.  Found on the schematic which edge connector carries the g segment input to the display board from the CPU.  Also found the pin which brings the f segment which was working.  Shorted the two together and VOILA!  The g segment lit!  Now I knew for sure that the display board was not getting the proper signal to generate a g segment.

Another few minutes of studying schematics and I was able to identify the CPU pin and associated PIA chip which generate the g segment and send it down to the display board.  A few minutes with the multimeter and I located an open trace from the 6821 to the capacitor which was installed between the chip and the edge connector.  This board had had some battery leakage earlier in its life and apparently this trace was partially destroyed in the process.  As time went by, the damage continued and finally the trace was broken.  I repaired the damage and there was the g segment, right where it should have been all along!

The lesson I learned was – before tearing into a suspicious board and willy nilly replacing every chip in sight, spend a few minutes looking to see if the suspect board is getting the correct input signals.  If it is, the suspect board is bad.  If not, the problem is upstream.  Two minutes probing the input pins to the board with 10 cent alligator clips could have saved me several hours of frustration and wasted troubleshooting time!

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Pinball Diary

October 27th, 2009

I’ve been working on a bunch of pinballs at a customer’s arcade.  These haven’t seen any attention for quite a while, so its more a job of triage then restoration.  The customer wants them more or less working, but “don’t go crazy”.   I take this to mean get them going pretty well but don’t spend  a lot of money in the process…

 First up was a Bally Eight Ball (Fonz) which the customer said needed new displays.  Since the playfield controlled lights were not strobing, I immediately knew it was an MPU problem.  Sure enough, only three flashes.  Memory tells me that this is probably a bad 6821 so I replaced U10.  Wish they could all be this easy!

Next up, a Bally’s Mata Hari with a drooping right flipper.  A check under the playfield revealed a bad flipper pawl – it was literally cracked along the weld, and was unrepairable.  A new flipper pawl and adjustment of the end of stroke switch and the flipper was back to normal.  By the way, whenever making a flipper adustment, ALWAYS check that the EOS breaks at the end of the flipper stroke or you will be replacing a burned up flipper coil!  Now that the flipper was fixed, checked out the rest of the machine.  Third player display was missing the 100’s digit.  Since it looked fairly clean otherwise, I decided to repair it.  Resoldered the header pins as a preventive move since these are ALWAYS cracked and will lead to all sorts of weird display problems.  For the missing digit, tested the usual culprits, the 100k resistors in the center of the board, and found one that was wide open.  Another quick fix, and a great looking display as a result!

On to a Williams Laser Cue showing a battery error in the displays.  This one was not so pretty.  Batteries leaked big time, destroying the battery holder, a good section of the MPU, and travelling in a straight line all the way down the driver board, adding a lovely shade of green to a whole bunch of components.  This customer does not want to spend a bunch of money on his games unless there is no other choice, so I took the boards out to see what I could do.  They got a good bath in hot water, followed by a scrubbing with white vinegar and a toothbrush, followed by more hot water.  I spot treated especially bad areas with a fiberglass brush to get rid of the last bits of visible corrosion.  After blowing the boards dry with compressed air, followed by an alcohol wipe down, I started in on the components.  A new battery holder, a couple of transistors, and the GI fuse, and we were back in business.  Whoever worked on this game before used some really creative resistor combinations to replace some of the original resistors on the driver board.  There were so many resistors piggy-backed together, it was a miracle they didn’t all short out against each other.  There were also HOLES burned completely through the driver board with all sorts of associated creative trace rebuilding, if you could call it that!  If this were my game, I would completely replace both the MPU and driver board, but he is just interested in keeping Laser Cue running well enough to collect quarters.  Since, for whatever reason, this section of the board was working, I left well enough alone!  I made a note to tell him that this boardset was working for now, but no guarantees on how long.  We shall see…

A Stern Golden Cue had its shooter knob pulled right off the shaft.  Since the York show was coming up that weekend, it gave me an excuse to go parts shopping.  Golden Cue also had a non-working upper left flipper.  Soldered a broken wire for an easy fix. 

Stern’s Harley Davidson powered up fine, but wouldn’t start a game.  Customer thouht the balls might be lost.  An examination of the VUKs showed all of the balls currently residing in the traffic lite VUK.  Again, a simple broken wire solder job and we’re good to go!  Made a mental note to order a new shooter button which was broken out completely. 

Sega’s Baywatch had some weird things happening with its DMD.  I noticed that the problems seemed to be vibration sensitive.  A few minutes experimentation led me to the 2-wire connector on the back of the DMD.  I never have much luck getting a 2-wire connector to stay on with any conviction, so I bent the two male pins apart from each other so as to require the plug to be forced on.  This seemed to provide enough friction to keep the plug tight and the problem was fixed. The extra ball button on the front of this machine was smashed also.  What kind of animals play here anyway??  The VUK at the top of the playfield next to the lifeguard station was interrmittant – the switch would only register when it felt like it.  Figured out the diode had a cold solder joint on it after a bit of experimentation.  No matter how I tried, I couldn’t fit my iron into the tiny space, so I had to remove the entire micro switch on its bracket.  Thank heavens for magnetic screwdrivers!!  Played a few games to check everything out.  Not sure why Baywatch doesn’t get a better rap – it is kinda fun to play!  At least to me.  Or maybe that’s just Pam’s red bathing suit talking!!

A look down the row showed a bunch of other games with various GI problems.  Made a mental note to bring plenty of molex pins and connectors next trip.  I decided to leave the rest for another day!

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