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SCSI CD-ROM troubleshooting and maintenance

jessenator

Well-known member
So I'm asking this more as a maintenance type of question thread vs 'I have an emergency' kind of help query, but figured I'd try to get some answers as to why I've been having similar symptoms across a number of optical drive, and why they keep crapping out in the same ways.

My drives are mostly non-Sony/Apple drives—Toshiba drives—all supported with FWB CD-ROM Toolkit drivers, and have at one point or another worked. I make a point of calling them out, as I've heard that Apple/Sony drives have issues, e.g. caps on the 150/300 e models etc. But if recaps are a necessity on these other drives, I won't shy away from that now I feel a bit more confident in SMD work. As far as condition, these drives are essentially lightly used or NOS drives, seeing limited use and have none of the dust cakes typical of the average vintage Mac/Clone. What is happening are these, usually in this order:

  1. Drives won't boot compatible media on the first or second tries (OEM or 1x burned), but will function somewhat normally once in the Finder
  2. Drives are unusually slow, intermittently slow (what I mean is these are 4x + speed drives and are acting slower than a boot floppy)—they kinda boot, but get halfway through the loading screen or finder load (not consistent when it hangs), and then just keeps going. I hear the drive seeking, or at least spinning and the head moving, kind of making a repetitive pattern of sounds, but nothing jarring, like a grinding noise, etc.
  3. Drives ultimately fail at loading media; refuse to mount



I'm wary of attempting a lens clean, even with lint-free cotton and 91+% IPA, and have been using air in most cases. And I don't want to keep purchasing "working pull" specimens of drives if they're really going to meet the same fate. SO far, the 12x Toshiba (1997) I recently bought has been working fine, but then again, so was the 4x (1996) replacement I bought earlier last year, which is now on stage 2 of the failure path above.

Are there general upkeep/maintenance items that one should attend to with optical drives of this vintage? I'm wondering what would cause these kinds of errors that isn't solved by an air-de-dusting.

 

Franklinstein

Well-known member
Some non-Apple drives don't boot from CD very well. Why this is, exactly, I can't say, but it's true. Maybe something to do with how the drive presents itself to the Mac at boot time or how it responds to queries. I dunno. Anyway you'd have better luck using Sony, Matsushita/Panasonic, or Pioneer drives than most others, at least as far as SCSI drives are concerned (ATA drives were newer and thus (the quality ones at least) were usually less fussy). I'd recommend avoiding other makes than these except possibly Toshiba and even then they're not preferred. TEAC, Nakamichi, Plextor, RICOH, and Yamaha drives are good, but they're often not ideal for trying to boot and, unless you're using a Mac clone, they often won't line up with your drive bezel and/or the eject button will be in the wrong spot. That said, I put an awesome Nakamichi compact 5-disc CDROM changer in my PowerCity/Starmax 4000 and an awesome Pioneer slot-loading DVDROM drive in a highly upgraded UMAX S900. I used D2CD to control the Nak and Toast's CD reader extension with the Pioneer.

Older drives often dislike CD-Rs, and most absolutely despise -RWs, so don't be surprised if your drive won't properly read these.

Because you're using SCSI, check termination. These drives aren't always well-labeled with their proper settings; sometimes the TERMINATOR jumper needs to be ON to enable termination, other times having the jumper ON disables termination, and some others (usually 2x or slower) use internal resistor packs that you have to install/remove manually. You have to check the manual for your specific drive to be sure. Alternatively, if it's the only drive on the bus, you can use a cable terminator if you have doubts (they make internal types too). The point is: termination can cause all kinds of problems, including some you're experiencing, so check this first.

Internally, most of these drives' mechanisms are similar: spindle motor and optical block together on an assembly that goes up and down to secure the disc between the spindle and the (usually magnetic) clamp hub thing. Normally the only problems with the spindle/hub are if the clamp hub breaks off or the friction-enhancer stuff starts to break down and become gooey, leaving a ring of gunk on the center hole of your disc.

As for the optical block, they're also pretty similar between makes, at least basically: lens, lens suspension, focusing coils, focus adjustment potentiometer, maybe a laser diode output adjustment pot, a prism, a laser diode, a pickup, maybe some small ICs, all on an assembly that slides back and forth via a toothed rail and train of cogs and/or a worm gear. Early drives used glass lenses and metal (usually copper) suspension for the lens, but newer cheaper drives use plastic lenses and occasionally plastic suspension. The plastic lenses cloud eventually, and the plastic suspension can sag, both of which cause problems at first and ultimately render the drive unusable. There's no fix for these problems: you have to replace the optical block assembly. 

You can try very lightly cleaning the lens with a lint-free swab and 90% iso, with very minimal pressure in a front-to-back manner. Don't swipe more than once or twice without rotating the swab, and don't repeat the cleaning with the same swab or you may scratch the lens with dirt that has adhered to the swab. The front-to-back motion is so that in case you do scratch the lens, it's easier for the pickup to compensate for (side-to-side scratches are more severe because of the rotation of the disc). 

If you have a drive that refuses to read any disc even after a cleaning, you can try adjusting the focus pot. This is a fiddly procedure that's meant to be done with specialist equipment with the drive in some sort of service mode, or even at the factory with the optical block removed from the drive entirely, but it can be done just by tweaking the pot one way or the other until the drive tries to read a disc, and then fine-tuning it to where it works reliably. You'll often have to partially disassemble the drive for each adjustment, which adds to the pain, but it can be done with just a power plug; the drive will try to read a disc without being attached to a computer. I've resurrected several Matsushita 4/8x drives doing this, even getting them to reliably read CD-Rs where they wouldn't even attempt to read any disc at all beforehand.

If the drive was used in an extremely dusty environment, some fine dust may have entered the depths of the optical block under the lens, which will cause problems. It's not recommended to use HFC-based duster to clean this out because that stuff can fog the optical components (same reason it's not recommended for use with cameras). Using very low pressure compressed (and filtered) air may help but sometimes, especially if a smoker was involved, it won't come clean with air pressure alone. You can try to disassemble the optical block and clean everything by hand, but you're on your own for figuring out how to do so; I don't have any suggestions and many of them were glued together.

 

jessenator

Well-known member
Thanks for the points you mentioned. Yeah, it's as I supposed: these devices are complicated and there's a few things to go wrong, some of which are irreparable. Still it's not over till it's over :)  Now that I know what to look for, I think I'll open the 4x back up and see if there's anything mechanical going on from the points above.

I think out of some lackadaisical dedication to OE restoration, I started replacing like for like on the PowerComputing machines. I kept the Apple/Sony CD for my ATAPI 4400 (and gave it a boost from 8x to 24x), but felt some cosmic tug to use Toshiba for the PowerTower (originally into the PowerWave). I think the PT actually had some NEC drive in it, but it probably was still a Toshiba, just with a different case/HW appearance.

SCSI termination might also be a factor here. When it was still consistently working, I was able to connect it (4x) to my Quadra 700, but …not in a traditional way. I had originally intended to use my non-working Bernoulli's case to house is, because what is it other than a PSU and SCSI connections. I stopped when the very tight-fitting SCSI ribbon wouldn't attach. But I actually had to remove termination to get the drive to work after Jerry-rigging it and the HDD (spinner) with the case open. (The quantum drive has the resistor pack termination)

I have a working 600i that I snagged for a low price, so that should hopefully make a better base. I've decided if I was to attempt this (external case solution) again, I'd be sure to connect everything in an external case with the term switch and everything, and pay a bit closer attention to how each piece is interacting with the others. 

Incidentally, here's where my patchy experience will kick in: Example, my Quadra 700: the SCSI2SD has termination enabled. Can I still use external SCSI devices? My fleeting memory from using it in my IIsi was that external devices would not work. I know they're different Macs.

 
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