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  • Chipbytex64@awesome.garden
    Sep 16, 2026, 5:20 AM

    Alright, I think that'll work.

    There's two signals on the 26-pin interface that don't usually show up on the 34-pin one. There's /CHGRST, which Sony does optionally map to pin 1 instead of GND on some 34-pin drives. And there's /HD LOAD, which actuates the head load mechanism. Most 3.5" drives don't have a head load mechanism, so that's by default wired to /MOTOR so the OA-D32W head will load at the same time the motor spins. On the Apricot side, that jumper will be cut as the Apricot ties /MOTOR to GND and a gotek doesn't care about head load.

    3D render of a small PCB with two double-row headers and a couple unpopulated jumpers.
    Render of the rear of the board showing the attribution and description.
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Replies

  • Chipbytex64@awesome.garden
    Sep 16, 2026, 10:08 PM

    Son of a bitch, it started working again. :[

    Ain’t no problem like an intermittent problem because an intermittent problem is not currently a problem.

    The Apricot, partially disassembled, playing music.
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  • Chipbytex64@awesome.garden
    Sep 16, 2026, 10:10 PM

    All I did was poke at the power connectors. Maybe this has been a dirty power problem the whole time.

    -12V does look noisy, but I don’t think that’s affecting anything in the floppy drive path.

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  • Chipbytex64@awesome.garden
    Sep 16, 2026, 11:05 PM

    Thinking about this a bit more, the symptoms don’t make sense. I’m not just getting disk read errors, I’m getting corrupted sectors in memory. I can see this because the boot will fail with bizarre glitches.

    Floppy data is protected with a 16-bit CRC, and the disk controller checks that. Occasionally you’ll get a corrupted sector out, but it should be pretty rare. To get them this regularly suggests that the problem is outside the floppy subsystem.

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  • Chipbytex64@awesome.garden
    Sep 16, 2026, 11:31 PM

    This, coupled with the other symptom I saw on Saturday - the screen flickering more than normal - suggests to me that maybe the system was browning out and some chips were not having a good time with that. Especially the ones far away from the power connector like the FDC. I dunno. It’s a theory.

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  • Chipbytex64@awesome.garden
    Sep 17, 2026, 12:22 AM

    Anyway, let’s see if we can do something about that -12V rail.

    A power supply, opened for inspection.
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  • Chipbytex64@awesome.garden
    Sep 17, 2026, 12:52 AM

    Here’s the 100uF cap on the -12V rail. I would say that’s not much of a capacitor anymore.

    A capacitor hooked up to an LCR meter reading 157nF with 5.36K ESR.
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