68kMLA Classic Interface

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Broken Hard Drive
Posted by: VMSZealot on 2023-09-09 05:49:54 I'm a menace and an idiot. I'm sorry, but it's true. I have a hard drive, from the early nineties, that was used in a store demo Mac in the UK (back then they were called Apple Centres). It worked, I moved it into another Mac, I used the wrong screw, and I popped the oscillator on the circuitboard. It had loads of demo software on it, all locked down with At Ease so that customers couldn't wreck it. I want to get it back! The oscillator is a KDS 2M 24.000, which I guess is a 24MHz oscillator - but it appears to have 4 pins. I haven't seen a 4 pin oscillator before, and I can't find the part online at all. What part can I replace it with? Any suggestions? (I have tried looking for a drive with the same controller board, an IBM WDS L80, but they're all selling for stupid money online.)
Posted by: Phipli on 2023-09-09 05:55:01 I'm a menace and an idiot. I'm sorry, but it's true. I have a hard drive, from the early nineties, that was used in a store demo Mac in the UK (back then they were called Apple Centres). It worked, I moved it into another Mac, I used the wrong screw, and I popped the oscillator on the circuitboard. It had loads of demo software on it, all locked down with At Ease so that customers couldn't wreck it. I want to get it back! The oscillator is a KDS 2M 24.000, which I guess is a 24MHz oscillator - but it appears to have 4 pins. I haven't seen a 4 pin oscillator before, and I can't find the part online at all. What part can I replace it with? Any suggestions? (I have tried looking for a drive with the same controller board, an IBM WDS L80, but they're all selling for stupid money online.) Do you have some photos please? Where are you located approximately?
Posted by: Daniël on 2023-09-09 07:49:39 Take off the oscillator entirely if you're able to. Then check which pins have traces running to them. It's not unlikely that only two pads are in use. Find a fitting oscillator of the right frequency, either four pin with the right orientation (check the datasheets), or a two pin that you can bodge between the two active pads. EDIT: On an IBM DCHS drive with a similar 40MHz oscillator (same package), it appears the pinout is the same as this one for an Epson 32KHz oscillator: Check if this is the same for yours. If so, getting a crystal between pin #1 and #4 is sufficient to get the drive going again, if you can't find one in this package. Doesn't need to be pretty, just functional.
Posted by: VMSZealot on 2023-09-10 06:58:03 Take off the oscillator entirely if you're able to. Then check which pins have traces running to them. It's not unlikely that only two pads are in use. Find a fitting oscillator of the right frequency, either four pin with the right orientation (check the datasheets), or a two pin that you can bodge between the two active pads. EDIT: On an IBM DCHS drive with a similar 40MHz oscillator (same package), it appears the pinout is the same as this one for an Epson 32KHz oscillator: View attachment 61789 Check if this is the same for yours. If so, getting a crystal between pin #1 and #4 is sufficient to get the drive going again, if you can't find one in this package. Doesn't need to be pretty, just functional. Thank you for this advice. I'll give it a go.
Posted by: bigmessowires on 2023-09-10 08:23:03 I think this is more likely to be an oscillator with an integrated driver circuit, rather than a simple crystal in a 4-pin package. Something like this maybe: https://www.digikey.com/en/products/detail/txc-corporation/7W-24-000MAB-T/2354939 or this: https://www.ebay.com/itm/372849736653 With this kind of 4-pin oscillator, pin 1 is usually an enable input or NC, pin 2 is GND, pin 3 is the clock output and pin 4 is VCC.
Posted by: Phipli on 2023-09-10 08:24:13 A photo would help.
Posted by: VMSZealot on 2023-09-10 09:10:32 The popped oscillator is bottom right in the image, next to the power connector.
Posted by: VMSZealot on 2023-09-10 09:11:07 I'll whip the logic board off when I get a moment, and get a shot of the underside.
Posted by: bigmessowires on 2023-09-10 09:36:24 OK, I'm guessing that's a DSX151GS package, in which case @Daniël is correct it's just a simple crystal, but the pinout is different. See attached datasheet.
Posted by: VMSZealot on 2023-09-10 09:41:51 Thank you - that's brilliant. I still can't see where to buy the matching part, but no matter. I'll find something compatible I hope. And thank you for your work for the community. I have my floppy emulator next to me right now - and it's a brilliant piece of kit.
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