I believe the head bump gap is 0.01 inch or less between the metal stop with the screws and the raised cam lobe on the stop wheel. The gap can be achieved by making a feeler gauge using a folded-over piece of aluminum foil. A caliper or micrometer helps achieve the desired foil thickness.
Thank you for the link to the C128 factory tests -- those are excellent! Regarding differences between models mentioned at 19:20, it also seems that the C128D 80-column test expects 64K of VDC RAM... so anyone who has bumped up their flat C128 from the stock 16K will want to use the C128D 80-column test instead. -- JC
If its just doing a vdc ram test, that should be good. There are however subtle differences between the revision 2 (most flat 128s, and 'plastic' 128D) and revision 3 VDC chips (relatively rare cost reduced version of the 'flat' 128, and 128DCR). For a complete test of VDC those differences should matter (horizontal screen positioning is off when using code for the wrong revision). The 128DCR (and cost reduced flat 128) come with an updated kernal which takes care of the v2/3 difference.
The top head on my C128DCR has one of the thin metal tabs broken. That's what you get when you move it continents and not insert a head saver or disk. Wonder how to repair this.
reading a directory does not mean you are aligned, because tracks are relative to each other. with the alignment of the start of the video you would be able to read most disks but you won't be able to format one using the standard commodore format, and if you use a fast format you will offset all the disk by half track.
(mostly in response to part 1) interesting, I've never encountered a 128DCR which needed new capacitors, but have seen ram issues quite a bit, either system or vdc ram or both, and at times issues with mos branded logic chips. Machines are surprisingly robust, I have one on my desk which has been running for 8 hours/day or longer for some 36 years now, and except for the fan and jiffydos roms is still 100% factory installed components. Have a second one which has barely seen any use ever (to the point of the keyboard still feeling like new when typing) which is completely factory original still, and also works fine. Sadly that one has the cost reduced power supply, which I really should replace just because it is a fragile and rather crappy pos with an extremely annoying 50hz hum (transformer core would need rework, not gonna bother)
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I believe the head bump gap is 0.01 inch or less between the metal stop with the screws and the raised cam lobe on the stop wheel. The gap can be achieved by making a feeler gauge using a folded-over piece of aluminum foil. A caliper or micrometer helps achieve the desired foil thickness.
You can just feeler gauges at an auto parts store.
Good Job, I haven't really ever tried a floppy alignment. I'll have to try one eventually. Looking forward to the controller video.
The bump stop test makes it sound like an Apple II drive 😂
Thank you for the link to the C128 factory tests -- those are excellent! Regarding differences between models mentioned at 19:20, it also seems that the C128D 80-column test expects 64K of VDC RAM... so anyone who has bumped up their flat C128 from the stock 16K will want to use the C128D 80-column test instead. -- JC
If its just doing a vdc ram test, that should be good.
There are however subtle differences between the revision 2 (most flat 128s, and 'plastic' 128D) and revision 3 VDC chips (relatively rare cost reduced version of the 'flat' 128, and 128DCR). For a complete test of VDC those differences should matter (horizontal screen positioning is off when using code for the wrong revision).
The 128DCR (and cost reduced flat 128) come with an updated kernal which takes care of the v2/3 difference.
The top head on my C128DCR has one of the thin metal tabs broken. That's what you get when you move it continents and not insert a head saver or disk. Wonder how to repair this.
That's a shame. No idea how to repair it
reading a directory does not mean you are aligned, because tracks are relative to each other.
with the alignment of the start of the video you would be able to read most disks but you won't be able to format one using the standard commodore format, and if you use a fast format you will offset all the disk by half track.
(mostly in response to part 1) interesting, I've never encountered a 128DCR which needed new capacitors, but have seen ram issues quite a bit, either system or vdc ram or both, and at times issues with mos branded logic chips. Machines are surprisingly robust, I have one on my desk which has been running for 8 hours/day or longer for some 36 years now, and except for the fan and jiffydos roms is still 100% factory installed components. Have a second one which has barely seen any use ever (to the point of the keyboard still feeling like new when typing) which is completely factory original still, and also works fine. Sadly that one has the cost reduced power supply, which I really should replace just because it is a fragile and rather crappy pos with an extremely annoying 50hz hum (transformer core would need rework, not gonna bother)
are you thinking of GCR ?
nail polish? its called lock tight.
lol
lock tight? its called loctite.
lol