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Posts posted by ymk

  1. I've recapped many Classics and Classic IIs.  The Classic especially, has many traces running underneath caps and with time, they will be eaten through.


    An ounce of prevention is worth a pound of cure here.  I'm not asking you to send them to me, but don't run vintage hardware into the ground.

  2. 19 hours ago, Tom2112 said:

    You mentioned that it should be configured for pull-up termination - pin 1 in the VCC column. I don't understand what that means. Do you mean only install the bottom resistor pack? (The one further from the SCSI connector.)


    Both resistor packs are either installed or removed.  There should never be just one installed.  The yellow resistors have a grey dot to mark pin 1.  The DIP socket has one more pin than the resistors, so one position per row on the socket is left open.  Looking at the PCB so most of the text is right-side up, pin 1 of the resistor pack is always on the edge of the DIP socket; on the left edge (labeled VCC on the PCB) for pull-up mode, or to the right edge (GND) for pull-down mode.


    19 hours ago, Tom2112 said:

    I haven't tried the MacSD _AND_ the HDD at the same time.


    Good, then your MacSD is probably OK.

  3. Hi Tom, I just spotted this thread.


    The MacSD ships with pull-up termination.  To run it together with an HDD one of the following must be done:

    1. Remove the HDD's resistor packs
    2. Remove the MacSD's resistor packs (FPT termination)
    3. Change the MacSD's termination to pull-down (pin 1 in the GND column, usually needed to work with Quantum's 110 Ohm resistor packs) 

    There is potential for damage if multiple devices are providing termination.  If it turns out yours is damaged, you can send it back for repair.


    First, try to get the MacSD running by itself with no other drives on the chain.  For the SE and SE/30, this requires pull-up termination (pin 1 in the VCC column).  The included card sets up a System 7.5.5 drive at SCSI ID 5.  Try changing the SCSI ID for the emulated HDD device in the macsd.ini file to 0.


  4. I make these with NOS ICs.  $26/ea shipped to the US.

    Edit: These are 256KB


    This same PCB accepts four ICs on the opposite side for 512K, so if there is demand, I can have them made quickly.  The chips for the two module sizes have different row/column dimensions, so a 512K module cannot be made with chips from a 256K module.


  5. Nice presentation.  MacSD is listed as not having floppy support.  While it doesn't emulate a physical drive, it does support mounting multiple floppy images at once.


    I also noticed SCSI2SD is listed as having floppy support.  What is the extent of floppy support on the SCSI2SD?

  6. On 7/30/2020 at 3:50 PM, jdlanza said:

    Ok, I’m convinced!  Any suggestions for good, quiet (QUIET!) fans?!


    • be quiet! Pure Wings 2 80mm, BL044
    • Noctua NF-B9 redux

    I run those in my PM6100 and Centris 610 at reduced speeds and they are virtually silent.  Convection cooling isn't viable for these machines.  With no fan, the top of the PSU will get hot, but even a slow fan keeps it near ambient.


    On 10/17/2020 at 6:45 AM, Crutch said:

    Right. You need a MAX232 IC to convert the Arduino’s TTL serial to RS232, and then you can convert that to RS422 just by wiring it up correctly. That’s what I did here. 


    Neat project.  Would feeding TTL directly to the Mac's opposite input pin work?

  7. Video favors lower capacitance so some cables use extremely thin wires. 


    ADB needs low resistance.  Go for heavier gauge wiring or build your own cable.


    I would not add external power to the bus.


    Measure the 5v delta at the end of the chain vs at the Mac and do the same for ground.

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