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MAC iicx

Gary C said:
But the machine itself works a treat in glorious 16 colours. Anyone know the SIMM spec to upgrade the 4.8 card ?
Click to expand...

It appears to use Apple's 68 pin VRAM SIMMs, which were also used in many of their 68k machines.

These SIMMs were never cheap, and the 512k variants were even more expensive. You can still get them on Ebay:

https://www.ebay.com/itm/142042841646

Someone made a batch of new sticks:
https://www.ebay.com/itm/114752740832

Just keep in mind that the Macintosh 4.8 Display Card is not accelerated, so higher resolutions and bit depths are going to be slower.
 
Found some originals for £6 which seems a bargin (if they work)

Speed is a moot point I suppose, these machines are never going to be fast, I just like to have everything working.

Which brings me to the floppy. It won't format and won't eject a disk so more tinkering required.
 
I'd suspect the grease in the drive has turned hard and crusty. As for not ejecting, either the grease dried up in the eject motor gearbox, or the plastic gears inside turned to dust.

You can use alcohol on a swab to remove the dried grease and then re-apply some light lithium grease to the worm drive and silicone spray to the sliding parts. For the gearbox, I'd just open it and hose the gears down with silicone spray and wipe away the excess. If you see any with broken teeth, you'll need to find replacements.
 
Floppy is a bit worse for wear.

The top head sits off the disk. Looks as if its been lifted too high in the past, probably to clean the head and bent the mounting leaf. Bent back and the head spring moved to a higher setting and the head will now make contact with the disk.

Drive gears look intact but need a greasing, but the head shaft seems a bit bent (!) in that its sticking in parts when through both holes. Will need a bit of working to get it to slide properly.

Must have had an interesting life.

I do wonder though if the BMOW emu would be a better bet.
 
Next problem, disk not spinning. Bit of metal stuck under disk drive motor, had to drive out the shaft and remove the lower plate to get it out, reassembled and spinning smoothly. Eject motor a bit stiff, bit of grease and now ejecting smoothly. Heads now in contact with disk.

But, when I format a disk, it steps from 0 to 79 ok but verify fails.

Need to test the heads for continuity, then check if I am getting a write signal.

Using HD disks which I imagine is ok ?
 
Annoying

The drive seems to work in every except when it comes to writing or reading floppies, which is a bit important

I have loop checked the heads and they all return good resistances that match the drawing within an ohm.

Monitoring the head during a format, I can see what looks like a good signal

When it comes to verifying, there does not seem to be anything coming back from the head, almost as if the disk has not been magnetised by the write.

I kow I have made a stupid mistake and separated the hub from the disk with the index reflector on it, but would that stop it formatting a disk ?

Probably need a new floppy which is a shame after fixing the HD. Probably the BMOW emu is more likely the right option, just doesnt mount well in the case by the looks.
 
Had a fun day repairing the broken tracks on the M0487 membrane (stupid things) with some conductive paint but at least all keys are now working. Probably should really look for an extended keyboard.

Got a replacement auto inject disk drive and that works fine (freshly oiled and greased). Still cant work out how, with heads reading a good resistance, with a good signal and in contact with the disk, the old unit fails to write anything, but its now also shed a tooth on the eject, so that is now a drive for spares.
 
I'd blame maligned heads if everything else was checked. It's very easy to damage the heads when cleaning them, or with a bad disk crashing the heads.
 
Even then I would have expected something back.It uses the same head to read and write so shouldn't care if its missaligned.
 
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