From: nospam@acme.com   
      
   Am 23.01.2025 um 17:00 schrieb John Robertson:   
   > On 2025-01-09 5:03 p.m., Jan Ernst Voß wrote:   
   >> Thanks for your replies!   
   >>   
   >> To say the truth, i am not really new to this group, but that's been   
   >> more than 30 years ago.   
   >>   
   >> Over the time, i owned 67 pinball games, all of them but the first   
   >> one, a Gottlieb's "Super Soccer" had failures. I've searched the   
   >> "Super Soccer" about a zillion to find the bad zero switch at the drum   
   >> units. I was 15 at this time, now i'm 62 years old.   
   >>   
   >> I repaired more than 100 machines, EM and SS as well.   
   >>   
   >> But games build by Playmatic are special: they use CMOS instead of TTL   
   >> logic.   
   >>   
   >> I bought a Big Town in 1987. The price was cheap, 70 DM (around 35$).   
   >> Both RAMs, both ROMs, and the CPU were dead.   
   >>   
   >> And other chips on the MPU were dead. I was able to get another   
   >> machine month later. It had good ROMs. This game was cheaper, 50 DM   
   >> (around 25$). I build a small circuit, using just 8 IS to do the job   
   >> of the 1834 ROMs.   
   >>   
   >> The ROMs were replaced by an EPROM 2716. The game went in attract mode   
   >> at once. Both games had a bad 74C42 on the decoder.   
   >>   
   >> Due to my job, i know most assembly languages of former machines. The   
   >> knowledge about these, i've made a "diagnostic board" for the   
   >> Playmatics, which was very helpful to find errors in the MPU of the   
   >> games.   
   >>   
   >> Now I have 2 bad "Big Town". Both are faulty.   
   >>   
   >> 1) Does not recognize contacts other than the coins, the credit, the   
   >> ball resting, reset, and the test buttons.   
   >>   
   >> 2) Shows irretating scores. "20" is the high score to date, new games   
   >> start with 200.020 points.   
   >>   
   >> That's it.   
   >>   
   >> Kind regards,   
   >> Jan   
   >   
   > Hi Jan,   
   >   
   > Wow, that is an unusual MPU and wiring diagram for we North Americans!   
   > I'm going by manuals and schematics I downloaded from ipdb.org -   
   > specifically Antar for the theory and schematics and Chance for the   
   > overall MPU diagram.   
   >   
   > The Antar schematic shows that the switches that are working share a   
   > common return line (page 24 of 35 in download Antar manual PDF) - so I   
   > suspect that you have an issue with other returns - and a logic probe   
   > that is happy with CMOS should help here.   
   >   
   > And as for the '20' on your display, I assume you have tried clearing   
   > the 5101 CMOS RAM (disconnect battery overnight - worst case clear), so   
   > it may be time to find a replacement RAM that is known-to-be-good.   
   >   
   > John :-#)#   
   >   
   Hi John,   
      
   first of all: a happy new year and so sorry for the endless delay.   
      
   These machines have no 5101 but 2 RAM's 1824, one of them powered by an   
   electronic capacitor. The games have no batteries. I guess, now the   
   stand to long. They reach the attract mode, but there is no reaction to   
   any switch. I hate these machines, but can use their playfield glasses   
   for other games. I have a "Four Seasons" (Gottlieb) and a "Banzai Run"   
   (Williams). Both of them are easy to repair and are in need of new   
   glasses for their playfields.   
      
   So, thanks a lot for your patience and sorrow for my awful english.   
   Kind regards, Jan.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)