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MAC iicx

Gary C said:
Well that nails it

Without a valid original sense code the (or at least my) 4.8 card does not output any video signal.

I connected Sense 1 to ground (RGB 15" monitor type) and the display leapt into life :) With a refresh rate of 75hz its well within my LCD monitors capability.

Just need to rebuild the machine now and see if the HD has any life left in it (and strip the floppy, never seen so much crap, its slot must be the major inflow of air to the chassis !
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That's weird, I've never seen a Mac II video card that required a monitor to be present to boot properly. Usually it just blasts out a signal regardless if something is connected or not. I have a few Nubus video cards and they all do that. I guess there are some that require some pins to be pulled low to work.

Maybe it's because the IIcx doesn't have an onboard video chip and the Nubus video card is treated differently.

Gary C said:
I can hear the hard drive spin up, then spin down so I think its dead
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Tried it with a different power supply? You may also want to remove the lid and inspect the drive, it could have stuck heads.
 
GiGaBiTe said:
That's weird, I've never seen a Mac II video card that required a monitor to be present to boot properly. Usually it just blasts out a signal regardless if something is connected or not.
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Certainly not. I've experienced that as well. I have a few Macs with two video cards and there's no way to get a picture on the second card unless a display was connected when powering on. Otherwise, the card does not produce a video signal. So it is safe to say: no sense pins = no video signal.
 
tipc said:
There are sense pins in the cable. I thought for Apple branded cards at least that was always the case.
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Of course, that's the whole point and the reason why the cards don't give video with nothing connected.

tipc said:
How is a computer/cards going to know to produce mono or color video?
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It doesn't need to know. Videos cards on the Mac are either dedicated monochrome or dedicated color cards.
 
What is 'interesting' is that what works with the IIcx, ie sense 1 to ground with sense 0 & 2 open circuit to select Apple 15" RGB monitor, does not work with the Performa 6200 which seems strange as it came with a 15" monitor ?
To get that to work I used the pin 7 to 10 extended sense code for VGA, did the Performa effectively come with a VGA monitor ?

In other news, strip down of the ADB keyboard is underway as the bars on the shift keys has corroded so much they stick and the rest is generally filthy.
 
While the sense pins are described by Apple as selecting the monitor size, what they really do is to select the display resolution. The Performa 6200 may only support VGA resolutions.
 
Timo W. said:
While the sense pins are described by Apple as selecting the monitor size, what they really do is to select the display resolution. The Performa 6200 may only support VGA resolutions.
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That's what I was wondering.

Certainly seems as if there isn't an overlap. Which is a pity as now I will have to make up another cable, ah well.

But at least its another 68k MAC rescue well on the way.
 
Timo W. said:
The Performa 6200 may only support VGA resolutions.
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The machine has 1 mb of shared video memory and supports 640x480 @ 15bpp, or 800x600 and 832x624 @ 8bpp.

Owing to the junk architecture of the Performa 62xx (putting a 64 bit CPU on a 32 bit bus, and using 68040 and 68030 bus emulators with slower devices), higher resolutions make the machine even slower than it already is. I had a Performa 6320 which used the same architecture with a faster 120 MHz 603e and it was just as painful.
 
GiGaBiTe said:
The machine has 1 mb of shared video memory and supports 640x480 @ 15bpp, or 800x600 and 832x624 @ 8bpp.

Owing to the junk architecture of the Performa 62xx (putting a 64 bit CPU on a 32 bit bus, and using 68040 and 68030 bus emulators with slower devices), higher resolutions make the machine even slower than it already is. I had a Performa 6320 which used the same architecture with a faster 120 MHz 603e and it was just as painful.
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Should it respond to standard monitor sense codes ?
 
Anyway, back to the focus of the thread.

The IIcx keyboard is totally stripped and cleaning is underway. I have had some luck with using HG Mould spray to help clean the plastics. Doesn't whiten quite like retrobright but has certainly made it look much better (its basically Sodium Hypochlorite and Sodium Hydroxide in solution).

Probably will need a new HD.

I have used the 80 pin to 50 pin adapters on DEC equipment with success, anyone tried a 20gb hd in a 68k mac ?
 
If the SCSI drive supports operating in 8 bit single ended mode, it should work. But you need to be careful about using newer SCSI drives because they draw quite a bit of power and can overload the generally anemic power supplies used in old 68k macs.

SCA-80 drives are usually 10-15k rpm drives and can pull a few amps each.

The other limitation is that Mac OS prior to 8.0 only supports HFS, which has a partition size limit of 2 GB. HFS+ introduced in Mac OS 8.0 supports up to 4 GB partitions, but both are not particularly robust file systems and have problems with large partitions and massive data corruption. I would stick with partitions of 1 GB or less to reduce the risk of data corruption.

Another problem is that you'll need to use the patched version of Apple HD SC Setup to format non-apple drives.
 
Keyboard back together but the caps lock key was a nightmare :)

The downlock wasn't working and the little copper pawl was not flicking across when the key was pressed down. Took it apart and the pawl was bent and cracked when trying to bend it back.
Made up a new one from a small bit of wire, bent to shape and its back working again (for now) but was really fiddly.

Hard drive heads were stuck, but I don't have my video lead setup for this machine so cant see if its now booting (but sounds like it) so need to make up a new lead.
 
Could not resist. Modified the Performa's cable and got the display back on the IIcx and it boots :)

However, the hard drive is playing silly buggers. When powered down and the heads go to the parked position, they then won't move until they are nudged again. There appears to be no static friction in the bearing (though obviously that is really hard to tell) and once off the landing zone, they move freely until powered down again. The head lock vane is moving away from the head before the heads try to move so its not getting stuck on that either.

Probably will end up replacing the HD after all which is a shame as it almost works.
 
Ah ha !

The Quantum prodrive disks have a known issue with sticky rubber bumpers. Surprisingly people have stripped down the actuator and replaced them on the LPS versions successfully without destroying the platters :) but the ELS seems to have a bumper under the bottom platter which is a none starter to remove.

https://68kmla.org/forums/topic/54709-quantum-prodrive-rubber-replacement/

Looks like the easiest method to restore this drive, is to put some rubber squashed in to touch the armature to prevent the head sticking on the bumper under the platter. Job for tomorrow :)

If I do replace the drive, it looks as if any low cost replacement would pull about 0.8A on the +5 and +12 lines which would be about 14W, which I would have thought should not be a struggle for the 150W psu (I hope). Worth a try anyway.

But the machine itself works a treat in glorious 16 colours. Anyone know the SIMM spec to upgrade the 4.8 card ?
 
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