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Thread: PS/2 Model 85 Troubleshooting

  1. #1

    Default PS/2 Model 85 Troubleshooting

    Hello All,

    I got a non-working PS/2 Model 85 as part of a take it all purchase. Troubleshooting it now I'm down to either the Main Board or the PSU as the suspects. Would appreciate if anyone can help with any guidance.

    Pulled all of the following
    • Memory
    • Expansion Cards
    • L2 Cache
    • Drives
    • Keyboard, etc.

    Only thing left plugged into the Mainboard is the ribbon for the speaker/power switch.

    At power on I get the following
    • Power supply powers on
    • Power Good LED on power supply is solid green
    • CR1 LED on mainboard is amber and solid
    • Front Panel power LED is solid greed
    • No beeps at all



    Reading the maint manuals I've found this points to a most likely cause of a Mainboard issue. Any thoughts on direction to take?
    Thank you
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  2. #2
    Join Date
    Feb 2017
    Location
    Guildford, U.K.
    Posts
    381

    Default

    Quote Originally Posted by VintageUsingVintage View Post
    Reading the maint manuals I've found this points to a most likely cause of a Mainboard issue. Any thoughts on direction to take?
    Thank you
    I don't come by here that frequently, check:
    http://ps-2.kev009.com/ohlandl/
    or:
    https://www.ardent-tool.com/

    but my first quick suggestions would be:
    1) Do you have a matched pair of 70ns, gold-plated, Parity (IBM presence detection) SIMMs in sockets A1 (leftmost) and B1 (skip 3 then next one). RAM *must* be in 64-bit Banks of pairs An & Bn.
    2) is the CPU correctly oriented for Pin 1 placement (unlikely not to be be, but best to double-check).

  3. #3

    Default

    Thanks for the info. I'll take a look at the links. I'm away for a bit so I can't play with the unit, but I suspect the ram is correct as it' was all IBM branded and matched. But unfortunately I don't have the specifics of it with me.

  4. #4

    Default

    Quote Originally Posted by VintageUsingVintage View Post
    Hello All,

    I got a non-working PS/2 Model 85 as part of a take it all purchase. Troubleshooting it now I'm down to either the Main Board or the PSU as the suspects. Would appreciate if anyone can help with any guidance.

    Pulled all of the following
    • Memory
    • Expansion Cards
    • L2 Cache
    • Drives
    • Keyboard, etc.

    Only thing left plugged into the Mainboard is the ribbon for the speaker/power switch.

    At power on I get the following
    • Power supply powers on
    • Power Good LED on power supply is solid green
    • CR1 LED on mainboard is amber and solid
    • Front Panel power LED is solid greed
    • No beeps at all



    Reading the maint manuals I've found this points to a most likely cause of a Mainboard issue. Any thoughts on direction to take?
    Thank you
    You are correct in that it's a systemboard issue. I recently restored an 85 K/N that had the same symptoms that yours is having now.

    Unfortunately, I can't tell you what exactly failed on your board, as I had a spare systemboard to swap into mine and haven't gotten around to trying to troubleshoot it yet. If I had to guess though, I'd say it's bad capacitors.
    Last edited by ButINeededThatName; May 13th, 2020 at 08:41 PM.

  5. #5

    Default This is gonna leave a mark

    http://ps-2.kev009.com/ohlandl/IBM_S...LED_Flash_Code

    LED stays solidly lit after SCSI POST executes - replace SCSI controller.

    Having said that, it depends. Inspect all SCSI related leads, look for deitrus on the leads, or God forbid, corrosion.

    http://ps-2.kev009.com/ohlandl/9585/...con_Capacitors
    This can be a bummer [said Pooh as he strafed the lifeboats]

    It may also be duff in the SIMM sockets, MCA sockets, etc.


  6. #6
    Join Date
    Feb 2017
    Location
    Guildford, U.K.
    Posts
    381

    Default

    Just a random thought, PS/2 Server 85s may have the "case intrusion" LogicLock switches which might have disabled the system.
    http://ps-2.kev009.com/ohlandl/9585/9585_DX_Planar.html
    See the equivalent Server 95 item:
    http://ps-2.kev009.com/ohlandl/9595/...html#LogicLock

    I have no experience with defeating a "locked" planar, but assume it involves clearing the RTC/CMOS and toggling one or both of the PAP Override (J6/JMP2) and/or PWD Override (J5/JMP1) jumpers and powering-on with the RefDisk in the A: drive. Do so at your own risk, or check with Peter:
    http://www.mcamafia.de/mcapage0/error_02.htm
    See error codes 182-184.

  7. #7

    Default

    WBST, I don't think that this is a PAP, that would prevent any change to the configuration.

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