(Topic ID: 222829)

6821 PIAs


By Theonlylilo

1 year ago



Topic Stats

  • 5 posts
  • 5 Pinsiders participating
  • Latest reply 1 year ago by greatwichjohn
  • Topic is favorited by 1 Pinsider

You

Linked Games

No games have been linked to this topic.

    #1 1 year ago

    Good morning to everybody! Just a little clarification before my summer holidays
    On Ebay I won an auction for 10 PIAs 6821... good price, for a Chinese counterfait parts of course! From the pictures looked original but once in my hands... ok, now I have them here...
    Is not the first time that I try them on bench (WMS driver board, with Leon test rom), they work fine but once in the flipper... problems problems problems...
    How is it possible? The bench test should be reliable, right?
    Thanks for suggestions...

    Ciao

    #2 1 year ago
    Quoted from Theonlylilo:

    Good morning to everybody! Just a little clarification before my summer holidays
    On Ebay I won an auction for 10 PIAs 6821... good price, for a Chinese counterfait parts of course! From the pictures looked original but once in my hands... ok, now I have them here...
    Is not the first time that I try them on bench (WMS driver board, with Leon test rom), they work fine but once in the flipper... problems problems problems...
    How is it possible? The bench test should be reliable, right?
    Thanks for suggestions...
    Ciao

    You would think so.. I have written some test ROMs from scratch, you could try them on the bench but they were designed to run in the game. Give them a try and see if they help you find what the problem in the flipper is.

    You can download them from here: http://pincoder.reversion.ca

    There is also a thread on this site where you can leave some feedback: https://pinside.com/pinball/forum/topic/new-williams-system-6-in-game-test-roms

    Let me know how you make out!

    #3 1 year ago

    I'd try the suspect PIAs in a different known good game. My experience with the used pulls 6821s you pay around $1usd each and expect around 10% to be dead on arrival bad and another 2% has infant mortality. If every single one works with the test rom but acts up in a real game you probably have some other kind of problem.

    Leon test is not full proof but it should discover most bad PIAs. Some kind of logical issue could slip through as leon's test rom uses no special patterns when controlling the output ports. Just flips all the bits at the same time.

    W65C21N should be fine (at $6usd or so) but they mention in the data sheet... "The W65C21N is plug replacement of NMOS and CMOS 6521 and 6821 devices with current limiting resistors". I don't think current limiting resistors are needed in any pinball application, but something to keep in mind.

    #4 1 year ago

    There’s a reason why they were named p.i.a.

    #5 1 year ago

    The past Russia ones seem mostly ok. Think 1 in 10 a dud! There should be more used good ones available from USA or Canada. With the Ultimate MPU, many of us no longer spend hours working on old Bally & Stern boards from 1978-1982. Same with 5101 ram. Times are changing towards replacing boards instead of working on them.

    Promoted items from the Pinside Marketplace
    $ 6.00
    Electronics
    German-Pinball-Modular
    From: € 3.70
    Flipper Parts
    Buthamburg
    $ 15.00
    From: $ 99.99
    Cabinet - Other
    Lighted Pinball Mods
    $ 90.00
    Lighting - Under Cabinet
    Rock Custom Pinball
    $ 244.99
    From: $ 40.00
    Various Novelties
    Pinball Photos
    $ 159.99
    Lighting - Other
    Lighted Pinball Mods
    $ 159.99
    Lighting - Other
    Lighted Pinball Mods
    $ 15.00
    Playfield - Decals
    Flashinstinct
    $ 79.00
    Lighting - Under Cabinet
    Arcade Upkeep
    From: $ 5,899.00
    Pinball Machine
    Pinball Pro
    From: € 50.00
    Playfield - Toys/Add-ons
    Creo Pinball
    $ 54.99
    Cabinet - Shooter Rods
    Lighted Pinball Mods
    $ 76.95
    Cabinet - Shooter Rods
    Super Skill Shot Shop
    From: $ 195.00
    Tools
    PinDoc Restorations
    $ 4.00
    Playfield - Decals
    UpKick Pinball
    $ 20.00
    Cabinet - Other
    Filament Printing
    From: $ 99.99
    Cabinet - Other
    Lighted Pinball Mods
    $ 5.00
    Cabinet - Other
    UpKick Pinball
    $ 95.00
    Playfield - Toys/Add-ons
    M&M Mods
    From: $ 9.99
    Eproms
    Matt's Basement Arcade
    $ 4.00
    Playfield - Toys/Add-ons
    UpKick Pinball
    $ 99.00
    Gameroom - Decorations
    Pinball Sales

    Hey there! Got a moment?

    Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside