68kMLA Classic Interface
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| IIe card can't read 5.25" disks? | |
| Posted by: dzog on 2020-05-17 17:07:08 Greetings Apple II friends. I am attempting to repair a IIe card I received in a lot. I recapped it and it seems to work OK, except for reading 5.25" disks. My lack of Apple II knowledge and experience is hindering my debugging ability. I was able to get it to read a ProDOS 3.5" disk (via the host Macintosh) and run applications. No obvious issues there. But, reading a 5.25" disk just makes the initialization(?) noise and then fails. So, it's talking to the disk somehow. I've tried cleaning disks, 3x different drives, and a bunch of different disks, all the same result. I unfortunately don't have any other Apple II gear to test with. Is this a known Apple II failure mode of some sort? A failure of a certain chip on the board? Any pointers are appreciated! View attachment Video.mov | |
| Posted by: Realitystorm on 2020-05-17 19:00:56 I assume you checked the drive model already to make sure they are supported? https://support.apple.com/kb/TA47189 | |
Posted by: dzog on 2020-05-18 06:42:12I assume you checked the drive model already to make sure they are supported? https://support.apple.com/kb/TA47189Yeah - they are all model A9M0107. As shown in the video, they make a satisfying noise but never seem to actually load any data. | |
| Posted by: bibilit on 2020-05-18 11:45:47 IIRC capacitor goo can be present under the pds connector or even corrode pins. | |
Posted by: dzog on 2020-05-19 17:03:16IIRC capacitor goo can be present under the pds connector or even corrode pins.Good call - I could just make out some unwashed goo/corrosion underneath the PDS slot near the cap. Hard to reach, but I poured in some vinegar, and also ran it through the dishwasher with detergent. Re-tinned the PDS pins with flux and a mini dab of new solder each. Haven't broken it worse yet 🙂 but still not reading any floppy disks! Is it interesting that the drive does do the "init" sound when access is attempted, but apparently will not read? Maybe I can get some sort of diagnostic software running via 3.5"/ProDOS; perhaps a disk copying software would lend some insights. | |
| Posted by: dzog on 2020-05-19 18:05:40 I did get a disk copy program running via 3.5" ProDOS. This is what I get reading from a 5.25" drive with a disk inserted. Error on every read. The Red LED lights up on the drive, and every 8 blocks it makes a small noise.  Video shows the behavior and the drive noise; apologies for the sad-sounding HDD in the background: View attachment IMG_8550.mov | |
| Posted by: AwkwardPotato on 2020-05-19 19:54:45 Grasping at straws here: In your recapping thread for this card, you posted a picture of the card after corrosion was removed w/ vinegar. That picture showed the component labeled SOMC1603, a resistor pack, and it appears that several signals going to the floppy port go through that component. Many of the solder joints on the resistor pack look dull/crusty; perhaps a bad connection on it is causing this problem? | |
| Posted by: dzog on 2020-05-20 21:27:13 That wasn't _quite_ it but it certainly led me down the path - thank you. We have victory! First recap quickly became first IC remove-and-reflow and finally the hacky (but working) fix you see in front of you:   Sequence of events: - Retinned RP1 and a variety of other things to no avail - Started testing everything with a multimeter - Culprit! Cap goo (which I had thought looked so minor) opened a trace going from RP1 to the IWM. Barely visible damage near the junction. - First attempt at fix (jumper from RP1 to IWM) first worked, then failed. - Newbie debacle interlude: in a debug attempt, I tried to "reseat" the IWM with a heat gun (a $30 basic low/hi 250/350C one I use for heatshrink) instead of retinning with the iron like I'd be doing with the others. Oops, the chip slipped and now it's totally misaligned. Beat myself up a bit. Ended up removing IWM completely, cleaning off pads, and using solder paste for the first time to reflow. Paste is magic! But I used too much and had to clear 4 bridges, total PITA. - The fix was flakey as RP1's leg was corroded and weak. It soon fell off. Quite fortunately it's a simple 100 ohm resistor pack and I have plenty of resistors on hand. - Ultimate destination is one of the connector pins; wiring straight into there was easiest for me. It's not the prettiest thing in the world, but it does mean I get to play with Apple II stuff now 😀 The happiest sounds: View attachment IMG_8565.MOV | |
| Posted by: Realitystorm on 2020-05-21 05:18:33 Glad you got it working, I've had a lot of fun playing with mine in my LC 475 (originally in a CC that needs a recap). I've put together a partial guide for using the card that you might find useful https://www.savagetaylor.com/2019/12/04/setting-up-an-apple-iie-emulator-card-in-your-68k-macintosh/ If you haven't already created ProDOS partitions, that should be a next step, it will give you a lot of flexibility for using the card. I have 4 setup on my SCSI2SD http://www.savagetaylor.com/2019/12/19/how-ive-setup-the-scsi2sd-that-i-use-in-my-lc-475/ | |
| Posted by: dzog on 2020-05-22 13:38:30 Thanks for putting those helpful resources together 🙂 Fix is working reliably for a few days now. Eventually I think I'll want to make this board repair a bit nicer for the long-run - get a replacement resistor pack, redo the pad and trace, a nicer reflow on the IWM. But for now I'm just stoked to be up-and-running with it. And, heck, the "homebrew" look is a bit endearing 😉 | |
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