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Servicing NeXT (Canon) MO Drives
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bkmoore



Joined: 01 Jan 2009
Posts: 183
Location: Germany

PostPosted: Fri Sep 25, 2015 10:45 pm    Post subject: Re: Yet another successful refurbishment story Reply with quote

paolo.bertolo wrote:
.....A little bit of lubrication (again WD40) on the motor bearings and straight it went back in the cube.....


WD40 means "Water Dispersant" and is not really a lubricant. It is very corrosive and can damage many materials. I would use WD40 to unstick my little brothers Schwinn Beach Cruiser, but would strongly advise against using WD40 within a 10 meter radius of anything containing electronics. Shocked Sorry for the warning, it sounds like you did a good job!!! Very Happy For small motor bearings, I would consider a light sintering oil that could probably be obtained at most hobby shops. Maybe there are other recommendations on this forum.

Another bit of advice I got from the vintage-stereo community is not to mount new caps flush with the board, but to leave a small gap. That way when the board expands or contracts, it doesn't stress the capacitor as much. Maybe more a factor in amplifiers, but might be help prolong life in general.

Edit: when you solder a cap, the connector expands from the heat. Mounting flush, it cannot contract properly and stresses the capacitor, which could cause leakage.
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Sun Sep 27, 2015 12:31 am    Post subject: Re: Yet another successful refurbishment story Reply with quote

Rob Blessin wrote:
Really nice write up Paolo and by the way welcome to the NeXT forums! Best Regards Rob Blessin


Thanks Rob, my pleasure to be part of this passionate and competent community!
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Sun Sep 27, 2015 1:33 am    Post subject: Re: Yet another successful refurbishment story Reply with quote

bkmoore wrote:


WD40 means "Water Dispersant" and is not really a lubricant. It is very corrosive and can damage many materials. I would use WD40 to unstick my little brothers Schwinn Beach Cruiser, but would strongly advise against using WD40 within a 10 meter radius of anything containing electronics. Shocked Sorry for the warning, it sounds like you did a good job!!! Very Happy For small motor bearings, I would consider a light sintering oil that could probably be obtained at most hobby shops. Maybe there are other recommendations on this forum.

Another bit of advice I got from the vintage-stereo community is not to mount new caps flush with the board, but to leave a small gap. That way when the board expands or contracts, it doesn't stress the capacitor as much. Maybe more a factor in amplifiers, but might be help prolong life in general.

Edit: when you solder a cap, the connector expands from the heat. Mounting flush, it cannot contract properly and stresses the capacitor, which could cause leakage.


Good point here. Actually, consulting WD40 web site they claim the "magic" stuff works, "cleans and protects", "drives out moisture", "lubricates", "protect corrosion sensitive parts".
They also mention spraying TV electronic boards for protecting them against oxidation.
I thought it could more or less fit the bill.
Clearly, better not to soak the engine with it or with any other stuff at all, I've tried to concentrate only on the bearings, applying it with a tiny brush rather than spraying it directly, actually the only thing I don't want to do is to open the motor casing. A capacitor is easy to replace, the engine is such a bespoke part there's probably no chance to fix it if something goes wrong.

Anyhow, good piece of advice, probably I've been a little na´ve here, surely there are some other specialised products more suitable for the scope, any other piece of advice is more than welcome!

Concerning leaving a small gap between the capacitor case and the board for compensating thermal expansion, here also is something it might be worth considering whenever compatible with the packaging space.

Of course I could only solder one connector at a time, so while the first one was getting soldered, the second one was still completely free to compensate any resulting tension.
My technique: insert the capacitor in place from A side of the board, on the B side bend the connectors in opposite directions until totally flat on the board. In this way the capacitor is properly located and stable, ready to be soldered.
Apply a tiny touch of flux paste (with a needle or a toothpick) in the gap between the board hole and the connector. The solder will then naturally flow in and fill the gap. Clip the exceeding length of the connectors.
Fast, reliable and repeatable, I could refurbish the whole motor board (the last one I did) in less than one hour.
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barcher174



Joined: 07 Dec 2012
Posts: 556

PostPosted: Sat Mar 26, 2016 8:36 pm    Post subject: Reply with quote

I -really- wish I could figure out what is causing the cables to go bad. They just randomly stop working. This also includes a cable I made myself BTW, so I'm just clueless at the moment.
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Rob Blessin Black Hole
Site Admin


Joined: 05 Sep 2006
Posts: 586
Location: Ft. Collins, Colorado

PostPosted: Sat Mar 26, 2016 9:13 pm    Post subject: Reply with quote

barcher174 wrote:
I -really- wish I could figure out what is causing the cables to go bad. They just randomly stop working. This also includes a cable I made myself BTW, so I'm just clueless at the moment.


No worries as I have load's of you guessed it new old stock NeXT Optical Drive cables. Best Regards Rob Blessin
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303-741-9998 Serving the NeXT Community since 2/9/93
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pentium



Joined: 23 Jun 2006
Posts: 1146
Location: Kamloops, BC

PostPosted: Sat Mar 26, 2016 10:42 pm    Post subject: Reply with quote

How are you testing the cables after they fail? Are you ohming them out and finding open lines or something?
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-NeXT 68040 Cube with NS 3.3 and 64Mb ram
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barcher174



Joined: 07 Dec 2012
Posts: 556

PostPosted: Sun Mar 27, 2016 4:20 pm    Post subject: Reply with quote

Yeah they check out fine when I test them with my meter. Here's my theory: I think the pins on the drive are slightly thinner than the usual standard header. This causes the cable to make an unstable connection after a limited number of insert/removals.
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Mon Mar 28, 2016 11:37 am    Post subject: Reply with quote

I'd rather look elsewhere, don't think cables can fail like that. What's the issue with the drive?
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pentium



Joined: 23 Jun 2006
Posts: 1146
Location: Kamloops, BC

PostPosted: Tue Mar 29, 2016 5:26 pm    Post subject: Reply with quote

First hand, the issue is that you might have a good drive but when it's plugged in the drive still remains either a vegetable or totally brain dead.
However if you have a cable for using two MO drives, you'll discover simply switching plugs (so going form drive 0 to drive 1) makes the drive function (after you've recapped it) again. It is something with the cables themselves. The ribbon could be more sensitive than usual to flexing or the spades flex to easily or as mentioned, the plugs might wear out prematurely.
I've only come across bad ribbon cable twice in my life before and in one case it was from pulling on the cable to unplug it and on the other it was not crimped properly.
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Sat Jan 21, 2017 3:05 pm    Post subject: Reply with quote

Hello Everybody,

any suggestion on how to best configure a dual MO drive set up? I have two working drives and the dual head cable.
When I just connect them (and disconnect any SCSI drive) everything gets awfully slow, takes forever to get to the login in window, way more than booting in the single MO drive set up. Past the login window basically nothing happens, apparently the system hangs.
The same MO disk works perfectly on either drive and boots flawlessly all the way through.
I suspect there's something I'm missing with the configuration.

Thanks in advance for your feedback!
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barcher174



Joined: 07 Dec 2012
Posts: 556

PostPosted: Sat Jan 21, 2017 6:52 pm    Post subject: Reply with quote

I've never actually gotten it to work. I wonder if you need to have a digital board on the MO drive with the connector in the second (normally empty) position?
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Mon Jan 23, 2017 2:40 pm    Post subject: Reply with quote

Made some progress... I could get both drives mounted in parallel, but still needs the SCSI drive for booting.

Apparently, you need to have a disk inserted in the slave drive at boot time, otherwise you get an error and the boot procedure halts.

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andreas_g



Joined: 30 Jan 2009
Posts: 413
Location: Austria

PostPosted: Tue Jan 24, 2017 12:48 am    Post subject: Reply with quote

paolo.bertolo wrote:
When I just connect them (and disconnect any SCSI drive) everything gets awfully slow, takes forever to get to the login in window, way more than booting in the single MO drive set up. Past the login window basically nothing happens, apparently the system hangs.
The same MO disk works perfectly on either drive and boots flawlessly all the way through.
I suspect there's something I'm missing with the configuration.

Thanks in advance for your feedback!

Hello Paolo,

I had the same issue with an emulated NeXTcube with dual MO drives. I therefore disabled it in the emulator (Previous). I did lot's of investigations on this issue while trying to fix it. My final conclusion is:
This is caused by a bug in the kernel. If only one MO drive has a disk inserted, the kernel will continuously poll the second drive for disk insertion. Because the controller cannot communicate with both drives simultaneously this polling of the empty drive will interrupt communication with the other drive. The scheduler for this polling obviously does not check if communication with the other drive is in progress. This causes communication errors and recovery from these errors causes quite severe slow down. If both drives have a disk inserted, everything should be fine.

Regards,
Andreas
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Tue Jan 24, 2017 2:48 pm    Post subject: Reply with quote

andreas_g wrote:

Hello Paolo,

I had the same issue with an emulated NeXTcube with dual MO drives. I therefore disabled it in the emulator (Previous). I did lot's of investigations on this issue while trying to fix it. My final conclusion is:
This is caused by a bug in the kernel. If only one MO drive has a disk inserted, the kernel will continuously poll the second drive for disk insertion. Because the controller cannot communicate with both drives simultaneously this polling of the empty drive will interrupt communication with the other drive. The scheduler for this polling obviously does not check if communication with the other drive is in progress. This causes communication errors and recovery from these errors causes quite severe slow down. If both drives have a disk inserted, everything should be fine.

Regards,
Andreas


Hello Andreas,

thanks for your feedback (and congratulations for the amazing job done on Previous!).

I can only confirm your findings, the problem seems to lay in a bug related to the communication with the secondary drive. As long as there's a disk inserted, the boot sequence goes on, otherwise it either completely halts or gets awfully slow.
I'm planning to run some kind of DOE for collecting additional evidence as soon as I have sufficient time, I will surely share the results.

Regards,

Paolo
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 54
Location: St Gallen, Switzerland

PostPosted: Sun Jan 29, 2017 1:28 pm    Post subject: Reply with quote

Quick update from my side.
I'm running a set of tests to check if and how two MO drives can live side by side.
I could manage to boot a 030 Cube with two MO drives and no SCSI drive.
Set up: boot worthy media in the master drive (tested with NeXTStep 3.3), whatever in the slave unit (must be loaded, though).
boot command is b od(0,0,0)
The boot sequence will soon halt reporting some error, the slave unit is not seen in the correct way (wrong drive ROM and wrong servo ROM).
At that stage, press "command+`" and at the prompt select "restart" (so press "r" key). Now the machine will boot flawlessly.
Shut down seems not to work properly though, the slave drive gets ejected, processes are being killed, but the machine does not shut down completely (you need to go again through "command+`" and then push the power button, but the media is not ejected as it should be, means at the next start up it will go through the check / repair disk procedure, which on a MO drive takes a lot of time).
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