Scrambled screen after connecting sd2iec-powerlead to user port upside down

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Don't Panic. Please wash hands.
  • I did the stupid mistake of connecting my sd2iec powerlead to the userport upside down. The connector I am using isn't keyed.

    When I turned the power on the screen got all garbled. After disconnecting the powerlead from the userport the screen remains garbled - the effect is kind of like a fried PLA.

    I have connected the mk2 to my pc and this works fine. No error is reported. The led on the motherboard is blinking though.

    I have tried different CIA chips, VicII chips and another cpu but it does not make any difference. When running a diagnostic cartridge the system actually gets thru the SID test before hanging up and you can see stuff is happening on the screen but it remains garbled.

    I guess I'll have to order another mk2 but please let me know if anything can be done to save this one ;(

  • If the power lead to the user port really only uses VCC and GND, then the GND signal will be connected OK (that's all corner pins). The VCC lead will end up in the PA2 position, where it loads the CIA closest to the user port. I'd therefore expect to "only" have a defective CIA chip, but nothing else affected. Of course I don't know what the sd2iec is doing when insufficiently powered, but again, it will ultimately only load the open-drain lines, which is what they are designed for.


    I therefore expect to find something else, maybe just a bad contact after swapping out the CIA chips.


    Can you post a picture of that garbled screen and the remote control menu output? There must be a hint on why the LED is blinking.

  • First of all, do NOT operate the board on the conductive antistatic bubble foil. It is really conductive and will affect function of the board.


    What you see on screen is already a sign of "a lot of things working": The border/background colours and colour RAM have been initialized, so the CPU is running. You may even be able to POKE 53280,0 (blind-typing) and see the border colour turn black - please try.

  • It works except when I use one of the CIA's which were in when I fried it. I ripped the 2 CIA's out of a known working C128 and tried them in just to make sure I didn't fry the ones I had on the foil - same result, garbled screen but goes black on 53280,0 \ 53281,0

    I guess CIA 2 got fried when I had the power connector on the user port.

  • The user port CIA is also the one that controls the video bank. We've had a case from a different customer who was working on the MK2 board while powered on (attempted to apply Luma fix if I remember right). The fault was similar to yours, and the repair was to exchange the Xilinx CPLD on the board. Although this is a paid repair, it's still a lot cheaper than a new board. This of course depends on where on the planet you are and what your shipping options to Germany are.

  • We're VoEC registered in Norway, so customs *into* the country are a breeze. Coming into Germany, it'll be some paperwork for us, as we need to complete a special form for goods that only enter the country for a repair. You need to *clearly* identify this as "return goods", declared as "zero value" because it is defective.


    Exchanging the CPLD is 61.51 EUR incl. materials and 25% VoEC, plus shipping (please check your last invoice for details, I don't know off the top of my head).

  • Thank you very much for all your help. Should I send the package to this address:


    individual Computers Jens Schönfeld GmbH
    Im Zemmer 6
    52152 Simmerath


    Is this correct?

    How will I pay?

  • Yes, that's the correct address. You'll only pay for a successful repair, and we'll notify you if it gets more expensive than that. YOu can either pay with a wire transfer or PayPal.


    Please ship today, as we'll be on holidays the first two weeks of July. I don't want the parcel to arrive when nobody is here to do the customs paperwork.

  • The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.