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SE FDHD: SCSI woes

Addicted

Well-known member
Hello all, good day,

TL;DR : In sum, I'm trying to resolve a dead HDD in an otherwise promising Mac SE FDHD. What follows is a description, some ideas, and a question about the 53C80.

--

A neighbor found her husband's old SE FDHD in the attic and I offered to check it out. It is a late model (RAM jumper, socketed battery). Inside, I found a dead but unexploded battery and what I believe is a 3rd-party HDD expansion. So, it has two 1.44 floppies and a stealth Quantum ProDrive 40 S sitting above them. I added more SIMMs, put in a new battery, and it booted 6.0.3 from a diskette. Video is good, sound works, both floppies are reading and booting 1.44 diskettes, ADB works. Have not tested the serial ports or external floppy. Finder shows 4,096KB RAM.

The Quantum has an APN sticker that reads 940-40-9401, a foil sticker that reads "40 S".. so I presume it is a "real" Apple HDD. It does lack the red-ink Apple logo sticker, if that matters. It has its termination resistors in their sockets.

I blew out the dust throughout the system, looked for any debris between pins, and used a dry cotton swab to really de-dust the fan. The fan is fairly quiet, so I have not rebuilt or replaced it.

The HDD, however, is not recognized. I hear it spinning very quietly and smoothly, and only the barest hint of heads moving (which might just be old bearings rattling periodically - it is very quiet, more or less periodic, and infrequent). If I attach an LED to its activity indicator, it blinks once during startup, then comes on and stays on. Disk Tools for System 6.0.3 does not find it. The internal ribbon cable has a small amount of wear and I have not yet done a continuity/short check on it.

So, theory 1: Perhaps the HDD is so old that it's taking too much current to spin up? I have no means to test this, I think. I have tested the power connector in-circuit and the HDD is getting a solid supply on the 5V and 12V pins.

I have a Zip 100 SCSI and its branded DB-25 connector cable. Placing this on the external connector also does not result in it being found. This is not the best experiment, as I do not know if I have a bootable, 7.5.5-or-earlier Zip disk with the Zip extension on it. I last used this Zip SCSI in the post 7.6.1 days.

So, theory 2: bad SCSI cable, perhaps shorts from insulation lost during installation or re-opening. Digikey has replacements for $25 each so, holding off on that.

So, theory 3: Dead 53C80. This is a bit of a leap with the small amount of information I have so far, plus I don't know what other parts could fail and result in this symptom.

I have removed the Quantum and its cable and my next test will be to try a different disk. I don't have a replacement internal cable, but I'll examine the existing one better, first. I'm waiting on the replacement disk now.

I will also try recognizing the Zip drive with the Quantum and its cable removed. I think I can create a Zip drive from an image using an ATAPI Zip250 I have on a Windows box. I just need to find an image with the Zip extensions.

Finally, just in case I cannot rule out the 53C80... I am in search of pinouts for the old 40-pin DIP Zilog 53C80 or a schematic of the SE. I have found and ordered the modern replacement for it from Zilog, but it is now a 44-pin PLCC. I believe this is the very PLCC used on the SE/30, and I'm willing to make a DIP adapter to retrofit it into my SE if I can determine which pins are which on the DIP40 packaging. I have limited reworking skills but may be able to get the old one out without lifting a pad -- but I will be lucky if I do.

So, question: I'm still searching this site, I'm sure it's here -- but if anyone can point me at an SE schematic or relevant 53C80 data sheet, my thanks in advance.

Thanks for reading this. I hope I have done the right amout of experimentation before posting, and described the issue well.
 

moldy

Well-known member
So, theory 1: Perhaps the HDD is so old that it's taking too much current to spin up? I have no means to test this, I think. I have tested the power connector in-circuit and the HDD is getting a solid supply on the 5V and 12V pins.
Are you sure it's actually spinning? I had a very similar Quantum drive in my hands and the grease solidified to a point where the disk would not spin on its own. Unscrewing the PCB and a cover below it let me "help" the drive to spin the platters with my fingers and boom - a clean boot straight away.
 

Addicted

Well-known member
Hello modly,

The disk makes a very characteristic whirr/whine that climbs in frequency and levels off shortly at a steady pitch. If I (gently) shift, tilt, or rotate the drive while it is powered on, I feel torque (gyroscopic reaction).
 

Berenod

Well-known member
I usually troubleshoot stuff like this with two BlueSCSI's I own.
One is the DB25 version, the other for internal use with the flat cable connector.

It's not clear from your posts if you own classic 68k macs yourself as you write you are working on one from a neighbour, if you do own some yourself (or plan to), those BlueSCSI's can be a nice and very usefull investment.

The DB25 is pretty convenient to use in conjunction with Basilisk on a modern PC, I pretty much use it as a thumbdrive for my old classic Mac's.

Anyways, in your case it would pretty fast pinpoint the problems you experience, if the BluSCSI works correct, you can pretty much rule out SCSI issues, and be sure the HD is the problem.
 

Addicted

Well-known member
Thanks for the idea, dramirez. It's been ages since I was 68k-Mac-savvy and I had forgotten about SCSI Probe. The Mac I am restoring boots from either SuperDrive, so this is a go. I'll see about building a floppy with a runnable app on it later today. I think I have found a 1.44MB DiskCopy image online.

I don't own any other classic Macs - I purged my attic a few years ago and now regret that (two LCIIIs, a IIgs, and an Apple //e with a Mountain Time Card..). An LCIII would be ever so handy in diagnosing another classic Mac. Berenod - I've looked at BlueSCSI and am hoping to avoid the expense, but I may take that route after all.

Thursday, a working 40S HDD should arrive. I hope that will 'just work'. Else, the dreaded Plan C: the replacement 53C80 chip is here. But, I have no hard evidence that it's the 53C80 at fault, so surgically replacing a 40-pin DIP is a bad plan. Also.. I'm trying to keep the restored unit truly classic, without modern improvements that outshine the rest of the system. (I may have to let go of that goal.)
 

Addicted

Well-known member
Thanks, everyone, for the advice.

Good news: the replacement drive arrived and works well. It's a later model, 50-pin but half-height, not Apple-branded, and it came with 7.5 already on it. It boots fine. Yay; its thinner body will allow more air circulation inside the chassis. The full-height literally was touching the back of the CRT.

So the logic board, the PSU, and the ribbon cable seem to be AOK.

The external SCSI Zip doesn't auto mount, but HD Setup can select it and read the volume labels off of its disks. So external SCSI is also looking OK. I just need to find an Iomega extension for 7.5.x and that may be all I need.

My main goal for the Zip is to have a second boot device in case something goes wrong with the HDD. My second goal for the Zip is to use it to back the HDD up ASAP.

-A
 

cheesestraws

Well-known member
The external SCSI Zip doesn't auto mount, but HD Setup can select it and read the volume labels off of its disks. So external SCSI is also looking OK. I just need to find an Iomega extension for 7.5.x and that may be all I need.

There are two ways to use Zip discs:
  • You can use them like big floppies by installing the Iomega tools. The driver is then part of those tools, and discs you format through them just have a big filesystem on them, like a floppy does. This means that you get all the features of the Zip driver, but they're not bootable, because they don't have a driver on them themselves.

  • You can use them like a hard disc, by formatting them with HD SC Setup. This way, they end up with a hard disc driver on them, and you can boot from them, but you lose the Zip-specific or removable features.
In theory it's probably possible to get the best of both worlds by putting the Zip driver or a subset of it on the cartridge itself, but I'm not sure whether it's actually practical or not. Never tried.
 

LaPorta

Well-known member
What you need is the Iomega Zip extension version 4.2. Later versions will not allow for Zip disk startup from an external SCSI drive. Get a copy of Zip Tools 4.2:


Install this on your SE. Zip disks should now mount just fine. If you want a startup Zip, reformat the Zip under Zip Tools 4.2, install a System Folder on it, bless it, and it should work fine. I ran a Plus for years off a Zip disk before all these great SD-SCSI solutions became available.
 

just.in.time

Well-known member
I believe the Zip Tools v4.2 boot limitation only applies to the Mac Plus. Specifically, when formatting the Zip disk, the machine doing the formatting needs to be using v4.2 for the Plus to be able to boot from it. In my experience, other machines don’t seem impacted by newer versions.

That said, v4.2 is the version I always install regardless of machine or OS version… pretty sure it’s even on my Beige G3 running 9.x
 

LaPorta

Well-known member
You may well be correct; I have not, however, ever tried it with an SE so I figured the same limitation may apply. It could be because of the Plus' early SCSI implementation.
 

Addicted

Well-known member
Again everyone, thanks for the encouragement and info. It kept me going.

I found a BinHex file of the complete Zip 4.2 install diskette (kudos: vintageapple dot net). Rather than expand it on a modern system and risk losing resource forks or hitting other translation flaws, I sent it over zmodem to the SE/00. I decoded it on the SE/00, and it produced an error-free .sea . So that paid off.

I've got System 7.5 up and running with two 1440K floppies, an internal 40MB, an external Zip100, 4MB, and a new PRAM battery. The video horizontal 'squeezes' (blinks very slightly narrower and instantly goes back to normal) once in a while, so I may try to improve that - later. It's still very very useable as it is.

Now that I can access my old Zip disks I can spin old gems like an original Zip Tools disk with the Zip 4.3 tools; Eudora; Norton Disk Doctor; various legacy printer and CDROM drivers; and if I decide to expend the RAM, the System 7.5.3 update.
 

Berenod

Well-known member
T
Again everyone, thanks for the encouragement and info. It kept me going.

I found a BinHex file of the complete Zip 4.2 install diskette (kudos: vintageapple dot net). Rather than expand it on a modern system and risk losing resource forks or hitting other translation flaws, I sent it over zmodem to the SE/00. I decoded it on the SE/00, and it produced an error-free .sea . So that paid off.

I've got System 7.5 up and running with two 1440K floppies, an internal 40MB, an external Zip100, 4MB, and a new PRAM battery. The video horizontal 'squeezes' (blinks very slightly narrower and instantly goes back to normal) once in a while, so I may try to improve that - later. It's still very very useable as it is.

Now that I can access my old Zip disks I can spin old gems like an original Zip Tools disk with the Zip 4.3 tools; Eudora; Norton Disk Doctor; various legacy printer and CDROM drivers; and if I decide to expend the RAM, the System 7.5.3 update.
The horizontal "squeezes" is normally solved by a recap of the analog board...

My SE had a bit of a "wobbly" image, and that got resolved after the recap!
 

Addicted

Well-known member
Hey Berenod - yes, I thought that the CRT jitters might be caps showing their age. I've ordered the replacement parts. I do some PCB rework now and then, but consider myself only a hobbyist, so I'm hoping I can get the old parts off without pulling any traces up in the process. I think it's not too risky.
 

cheesestraws

Well-known member
The SE analogue board is pretty chunky. I've always found it reasonably easy to work on—and I'm not good at PCB rework at all.
 

Addicted

Well-known member
I recapped the analog board, and replaced the fan while I had the board out. Along the way I did find one solder bump that looked slightly corroded; I desoldered down to a shiny bare pad and made a fresh connection. No signs of cap leakage or cap bloat.

This wasn't very hard. The only challenge was that my iron is a little small for those large flood traces, and so removing a few of the old caps took some patience.

Now the video is rock solid. The flicker was so infrequent that I was ready to just live with it, but wow... it's so much better to have zero flicker at all.

Unless I chance upon a great deal for some SE/00 PDS expansion card, I think this restoration is now complete. I've tested everything but the printer port, external floppy, and the PDS slot. The case is in excellent condition and so I won't retrobright it; I've never done that and want to gain experience on some beat-up case that won't lose much if I do a poor job.
 
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cheesestraws

Well-known member
Nicely done :). Yup, an iron with lots of heat output helps but in the absence of that, patience goes a long way.

There's no call to retrobrite at all unless you want to: if you're happy with it the way it is, leave it like that indefinitely. I personally don't retrobrite any of my stuff, because I'm not convinced it's terribly good for the plastic, and it wouldn't seriously increase my enjoyment of the machines. But that's not to say you shouldn't, if you want to. There are so many SEs out there, at least so far: you can do what you want with yours :)
 
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