IIGS recognizes 5.25" drives but not 3.5" or smartport? Help?!

[spacecadet]

Thanks! That is really helpful. I have a feeling your reading is a lot more normal than mine is. I've also asked Steve from BMOW to verify that my readings are not right since he seems like the guru of this DB-19 connector, so I'll see what he says too. I've actually got my fingers crossed that this is what's wrong; then it'll hopefully be a lot easier figuring out why it happened.

[Bloodnose]

Glad to help someone so persistent.

 

I was horrified to hear your confession about hot-plugging. For the love of God don't do that. Not even the ADB. Whenever I had to stop a hung process, with the drive light still lit, I'd power down, which lets everything ground out. I highly doubt this equipment was engineered to handle hot-plugging, and even a power outage risked damage.

 

Can you trace those pins to an IC which can be replaced, though with quite a bit of solder work. It still makes you consider if it's worth replacing an IC from a working board. The possibility of getting new replacements with exactly the same characteristics is daunting.

[Keatah]

ftp://ftp.apple.asimov.com/pub/apple_II/documentation/hardware/schematics/Apple_IIgs_1MB_Schematic.pdf

ftp://ftp.apple.asimov.com/pub/apple_II/documentation/hardware/schematics/Apple_IIgs_256K_Schematic.pdf

 

Page 4, upper left, of the 256K schematic shows most of that connector going to the IWM - which is your disk controller chip. 6 goes to 5V and 10 goes to the sense line.

 

Additionally you can try running the built-in diagnostics. I don't know whether or not they query the IWM. And if they do, how far into it they go. Mine don't show errors, but then it's all working. Worth a try.

Hold down both <Open-Apple> & <Option> keys while turning on the power.

 

There are more advanced diags on disk, but considering...!!

Do you have any disk controllers of any kind that go into the slots?

 

[spacecadet]

Well, I more or less ruled out pin 10 tonight - copy protected 5.25" disks are still copy protected, while non-protected disks aren't, which is supposed to not be the case if that pin is shorted. I suppose it could be intermittent.

 

I now suspect the VGC chip. I traced the output from pin 4 and find that it terminates at the top right pin (not sure of the #) of the VGC. I then looked up the VGC chip by part #, not initially knowing what it does, and found this thread on another site: https://68kmla.org/forums/index.php?/topic/27060-iigs-no-longer-seeing-35-drives-bad-vgc/

 

Interestingly, he also thinks he might have done it himself (or rather, his son did it) hot-swapping by mistake.

 

I definitely feel like I'm on kind of a wild goose chase here but everything's bringing me a little closer and a little more confident in the real culprit. I no longer really suspect my PSU, I think my drives are ok, I think the Floppy Emu is probably ok. I think the two most probable culprits are either an intermittent or near-short on pin 10 of the floppy connector, or a bad VGC chip. But the fact that it happened on both boards suggests that the most likely root cause is me pulling something out when I shouldn't have.

 

Apparently some earlier boards, including ROM 01's, have socketed VGC's. Unfortunately neither of my boards do, so I can't really fix them. But I'm going to be *extremely* careful when I get the new board.