Laser 128 5.25" floppy drive tune-up / fix - just grease and clean

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Laser 128 5.25" floppy drive tune-up / fix - just grease and clean

Got my childhood Laser 128 back.  (c) 1985 VTCL, Made in Hong Kong.

Symptom:  System boots to ROM message, but disk doesn't boot, drive seeks forever and disk light stays on forever.

Short Fix:  Adjust calibration screw in back of Laser128.  Failed.  Tried using a cleaning disk.  Failed.  Dissasembled Laser128 case, removed shield from floppy drive, found that head slid roughly and rails had gunk/old lubricant.  Used over-the-counter isopropryl alcohol and q-tips to thoroughly clean the magnetic head, and also the slide rails.  Applied Prusa 3D printer lubricant sparingly to slide rails.  Head started sliding much better.  Re-assembled.  Success - the Laser128 now boots all my old disks, sounds MUCH BETTER (much, much more quiet now), and seems to be done having intermittent issues.

Lesson learned:  Avoid cleaning disks, take the time to dissassemble your unit.  Plain isopropyl works to clean heads.  Prusa 3D printer lubricant will hopefully last on these rails.  Not sure what type of lubricant it is, but presumably it is a type of lithium grease.  Can use ADTPRO transfer feature as a crude/coarse method for dialing in your RPM's.

 

TLDR Fix:  Laser 128 is an Apple IIc clone.  I don't know about the disk drive, but assumed the internal 5.25" disk drive on Slot 6 Drive 1 is also some sort of custom/cloned drive.  In any case, these Laser 128's have the drive speed adjustment screw (potentiometer presumably) accessible from a hole in the bottom of the case.  This is accessible without dissassembling.  The only problem was I couldn't run an RPM calibration software, because I couldn't boot the disk!

The next best trick I had was to use the ADTPro and serial cable to a Windows PC.  I followed the bootstrap instructions to boot up ADTPRO on the Laser 128.  Worked great.  Next I tried formatting a disk in the internal drive.  It kept failing.  So I turned the disk calibration screw all the way clockwise, and all the way counterclockwise, and then tried to turn the screw back to "center" as best as I could guess.  And then kept trying to format and kept turning the screw little itsy bitsy clockwise (or counterclockwise) until the disk formatted.

Next I attempted to send a .dsk image from ADTPRO on the windows computer to the Laser 128 and write to the real floppy.   Well, it did try to write, and got through successfully, but had lots of write errors.  So I kept reformatting the disk and trying the ADTPRO receive/write to floppy disk while making tiny adjustments to the speed calibration screw on the back of the laser 128.  I also tried an old cleaning floppy disk I had with isopropyl on it (yes I know, bad form to do this, doesn't work, ill-advised, etc.)

Eventually I was able to get a formatted and programmed disk with no write errors.  By the way, the disk I decided to write was MECC Computer Inspector (image available on-line), because MECC Computer Inspector includes a disk speed/RPM test that you can run on your drive with a blank floppy.  I was able to boot this newly minted disk, and running the RPM speed test, it gave me 305 RPM.  It said the suggested range was like 296 to 302, with an ideal speed of 299.  Well I dialed into 299 and... now my disk wouldn't boot.  I bootsrapped ADTPRO and I had issues formatting and writing the disk.  For whatever reason, it turns out the sweet spot for this Laser 128, according to Computer Inspector, was about 303-305 RPM, which is outside the range.  (On an aside, a disk written at too high of an RPM will probably not be readable once you adjust the RPM into range, and vice-a-versa.  Someone who understands maths could probably explain it to us some time) .  On another aside, I tried Copy II Plus but absolutely could not find an RPM/speed test in there.  I tried like 3 or 4 different version of Copy II Plus.  Clearly I don't understand that software (dad was the one running Copy][Plus back in the day; I was 8 years old).

Well luckily I happen to have a working Apple IIc and an external Apple IIc disk drive.  So I loaded up a separate copy of MECC Computer Inspector and ran the speed test on my Apple IIc drives.  I got 297 RPM on the external drive and 298 RPM on the internal drive.  Next I took that same exact external drive (that read 297PM on a working Apple IIc), connected it to the Laser128. So the lesson I learned here is the RPM's reported by Comptuer Inspector on my laser 128 aren't exact, because that same drive that reported 297 RPM on an Apple IIc was now reporting abour 302 on my Laser128.  So next I dialed in my Laser128 internal drive to 303 and left it as-is.  Even though 303 was outside of range, it seems my Laser128 RPM's are reporting  high in Computer Inspector.

Still having intermittent write issues at this point though, even with speed presumably dialed in.  And drive can only boot some of my disk fleet, not all, and even booting those is intermittent with boot errors.  At this point I dissassembled the Laser 128 and removed the shield to the floppy drive, cleaned the magnetic head and slide rails with q-tips and isopropyl (presumably 70% - whatever walgreens sells), and applied Prusa 3D printer lubricant (presumably white lithium grease) to the rails sparingly.  Reassembled and now this Laser128 is running like a champion.

 

I know this is old hat for everyone.  Hoping this post might help one fellow Laser 128 owner at some point in the future.  Have a nice day and thanks for hosting this website.

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"It's not always the head!"Ok

"It's not always the head!"

Ok, so this Laser 128 floppy disk drive continued to give me fits.  Intermittently working - games freezing, sometimes disks not booting, etc. and seemed to be getting worse again.  Long story short, there are other items that need to be cleaned and/or lubricated other than the magnetic read/write head itself.  So back we go again to dissassemble the Laser 128 and pull out the floppy drive... Here are other items to fix while you're in there:

  • Just dissassemble as many parts and assemblies as you can and clean the fuzz out of the whole darn thing.
  • Check the large round motor that spins the disk itself.   
  • There is a smaller idler pulley (coupled to the large motor via a rubber belt). 
  • There's an additional small motor that moves the read/write head carriage.
  • And of course there's the rails that the read/write head carriage rides upon.

Once I flushed and cleaned all the motors, my mysterious disk read/write problems disappeared.  And also, the drive is *ridiculously* quiet now!  Don't get any chemical stuff on the rubber belt just to be safe.  I also took the time to dissassemble the entire thing and clean up the unit.  Managed to direct short the (+) and (-) coming in from the power supply and blew my original Apple IIC power supply.  Pro tip, use a modern power supply with overload protection when doing your dissassembly and testing.  Apple IIC power supply does have an internal fuse, but you have to use a hacksaw to open it... not sure how to close it after that :-/.

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I followed this with interest

I followed this with interest, because mainly, these problems rarely show up on Apple II branded drives, the Shugart/Alps based Apple drives and clone drives out in the wild based on those mechanisms.  

I wonder (a) what mechanism these drives are that VTech used for their Laser 128 and why did the lubricants fail?  

Sure lubricants dry up over the years and leave residues in their place, and I have been known to lubricate and re-lubricate old 5.25 drive components, but never because of a failure, only as a preventative maintenance activity.

 

I also find it curious that there is a calculted speed discrepancy in your VTech drive between your Laser and your IIc.

Do you have an Apple drive you could move over to the Laser to see if the speed discrepancy follows it?  I suspect it would, as it sounds like it could be a system timing issue in the Laser.

Incidentally, when I do speed calibrations I always do it visually using the stroboscopic sticker on the spindle, or more recently, scribing a thin vertical line on the drive's spindle itself and using a smartphone strobe app for measuring RPM.  Only after setting it to 300 RPM that way do I compare it to a utility like MECC Computer Inspector or, my go-to utility for drive related matters, APTEST.

 

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Laser 5.25 mechanism

Laser typically used Chinon drive mechanisms.  I still have several in great working condition and they have had very little maintenance ove the last 35 years. I tuned the drive speed on a lot of Laser 5.25" drives and also non Laser drives on Laser 128's and also on //es.  Back in the day, I normally used Copy ][ Plus and tuned them to 298.5 most of the time.  The drives were used in a school computer lab and were oftem mixed and matched.  I even used Franlin disk ][ clones with DB19's adapters into Unidisks on //e s and Lasers. I don't remember and timing descrepency between Lasers and other CPUs.  Is your Laser 128 a stock 128, or might it be an EX or EX/2 running at 2 or 3.6 MHZ?   Now I am curious.

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baldrick wrote:...Do you have
baldrick wrote:

...Do you have an Apple drive you could move over to the Laser to see if the speed discrepancy follows it?  I suspect it would, as it sounds like it could be a system timing issue in the Laser.

Incidentally, when I do speed calibrations I always do it visually using the stroboscopic sticker on the spindle, or more recently, scribing a thin vertical line on the drive's spindle itself and using a smartphone strobe app for measuring RPM.  Only after setting it to 300 RPM that way do I compare it to a utility like MECC Computer Inspector or, my go-to utility for drive related matters, APTEST.....

I stupidly did not take any photos of this Laser 128 drive while I had it all tore apart.  Next time I'm digging around inside there I'll take some photos of both sides of the internal drive.  I believe you are correct about timing issues in Laser 128.  I took an Apple A2M4050 external drive - connected to my Apple IIc, inspector reported 297 on that external drive.  I took that same A2M4050 external drive and connected it to this Laser 128 and inspector reported 302 RPM's.  I assume that connecting an apple internal drive to 6/1 would report the same way ("fast" on this particular Laser).

This time around, I also took the time to calibrate the internal drive by that black/white calibration sticker on the spindle by using an incandescent bulb.  This Laser 128 drive has the same black/white pattern for 60 and 50 Hertz on it that most drives have.  Once calibrated (I tried to make it so the squares weren't moving at all), inspector reported 303 RPM for the Laser 128's internal drive.  So, presumably calibrated to 300 RPM's this thing was still reading "fast" at 303.

I have been on the lookout for better diagnostic software than computer inspector.  I'll go search up a copy of Aptest!

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8BitHeaven wrote:Is your
8BitHeaven wrote:

Is your Laser 128 a stock 128, or might it be an EX or EX/2 running at 2 or 3.6 MHZ?   Now I am curious.

This is what I would call the most "basic" model of the 128's.  This is the one with the rectangular "LASER 128 Personal Computer" sticker over a hole on the front case (i.e. if you removed this sticker there'd just be a gaping rectangular hole in the face of the case).  It's all black and grey (no red, no EX, no EX/2, etc.  Just basic. ROM version 3.0 according to the boot-up screen).  In fact when I pulled the mainboard, on the back side were about 10 or 15 wires soldered onto the bottomside of mainboard after the fact.  I didn't stare at it too long to try to figure out what the wires were doing.

 

 

 

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Interesting discussion, let

Interesting discussion, let me know if there's anything particular you want to see in there and I'll look out for it next time I've got it open.  You can see we wore the letters off the keys playing strategy games on this computer growing up!

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8BitHeaven wrote:Laser
8BitHeaven wrote:

Laser typically used Chinon drive mechanisms.  I still have several in great working condition and they have had very little maintenance ove the last 35 years. I tuned the drive speed on a lot of Laser 5.25" drives and also non Laser drives on Laser 128's and also on //es.  Back in the day, I normally used Copy ][ Plus and tuned them to 298.5 most of the time.  The drives were used in a school computer lab and were oftem mixed and matched.  I even used Franlin disk ][ clones with DB19's adapters into Unidisks on //e s and Lasers. I don't remember and timing descrepency between Lasers and other CPUs.  Is your Laser 128 a stock 128, or might it be an EX or EX/2 running at 2 or 3.6 MHZ?   Now I am curious.

Interesting.

I have some Chinon external half height drives and they're excellent.

Except that I have one that is extremely stubborn and doesn't like starting up properly.

I will try doing that clean and re-lubrication technique on it.  It doesn't look like it's dirty or bound up, but who knows?

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Guide rail lubrication

Concerning guide rails: the Disk II service manual has a pretty clear (and slightly witty) warning on lubrication. That applies to the Disk II, of course. Still, probably a good idea to be careful also with other drives.

"No matter how tempting it may be!" :-)

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No longer applicable

During the service life of the drives, that advice could make sense. Certainly excessive or the wrong type of lubrication could cause a lot of problems.

But today when these drives are 40 years old, the advice does not apply anymore. The factory grease has dried up.

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robespierre wrote:The factory
robespierre wrote:

The factory grease has dried up.

 

As I understand it, Apple did not grease the rails of the Disk II - for exactly that reason. That's why they recommended to use alcohol to clean the rails - and resist the urge to apply grease.

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MacFly wrote:robespierre
MacFly wrote:
robespierre wrote:

The factory grease has dried up.

 

As I understand it, Apple did not grease the rails of the Disk II - for exactly that reason. That's why they recommended to use alcohol to clean the rails - and resist the urge to apply grease.

Many petroleum lubricants will degrade plastics.  This is why they wrote that.

However, there are quite a few advanced dry and nano-particle lubricants that exist today that could be beneficial.

That said, the drive sleds probably don't need lubrication at all anyway.

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Dang.  No matter how tempting

Dang.  No matter how tempting... :-/.  Now I'm going to lose sleep thinking about tearing apart all these bad boys again to degrease the carriage rails.  I guess I only thought about doing it because on the Laser 128 presumably it had been previously greased, because there was some nasty dried up junk on my Laser 128 floppy drive rails.  But, then again, maybe it was jusst other gunk that made its way in there.  

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Greasing the rails

The Chinon drive mechanism often found in Lasers had a very small amount of lubricant on the sliding rail parts and I have greased many of them.  Apple 5.25 drives on the other hand seldom need it.  The Chinons do get gunky and I clean it with alcohol.  Back in the day I often used a tiny bit of graphite.  I have also used a small ( 1 mm diameter) ball of lithium grease on a toothpick.  The trick is to help it slide smoothly without leaving enough to also contaminate the heads or media. A tiny amount of lubricant properly dispersed goes a long way, better to under do it than over do it.  I knew some people who preferred a light oil like 3-in-1, but I always felt it was too easy to get way too much and have a splatter contamination problem. 

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self-lubricating?
MacFly wrote:
As I understand it, Apple did not grease the rails of the Disk II - for exactly that reason. That's why they recommended to use alcohol to clean the rails - and resist the urge to apply grease.

A sliding contact needs some form of lubrication or it will eventually bind as the two surfaces tear gouges in each other. There are such things as self-lubricating plastic resins (such as acetal) but their effective life is also not unlimited.

However it's more likely that a dry lubricating film was used because they didn't want to fling droplets of grease or oil around inside the mechanism which could foul the heads or media. It's possible that they used a PTFE lube such as Tri-Flow.

Today the best approach would be to use a very thin film of polyalkylene glycol based grease, of the type that floppy drive manufacturers did specify for their rails and worm gears. The speed the head carriage slams back and forth is an issue for any heavier lubrication because it could cause the problem with flinging droplets.

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