Macintosh SE restoration

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Macintosh SE restoration

As you might have noticed I am restoring an SE! Sorry for the many threads, I just didn't want to hack the existing ones with OT questions.

 

I have a couple more questions for this system.

1. Battery. I removed the Varta battery (which surprisingly has still 2.9V in it!) and found that my CR2032 battery holders really don't fit elegantly. I'd like a better solution. Before re-inventing the wheel I was wondering if someone has come up with a good solution. Either a better holder or maybe a small PCB interposer to allow a standard holder in place. Maybe - if height allows - to be installed vertically? If not, I'll try to design one and share here!

 

2. The computer fails to boot every now and then. I turn it on, I have the "fine diagonal lines background". But after around 17 seconds I normally hear a "click" from the speaker and the computer finally boots. Sometimes that never happens and the computer stays with that background forever. If I reset using the button, it works fine.

It seemed it was happening when cold but today it happened after being off for a couple of minutes. Voltages seem ok, maybe -12V is on the low side (-11.6V) but I have a feeling it's not such an important voltage.

 

I can check the reset line but I was wondering if anybody had any ideas - maybe it's a known issue with this machine!

 

Thank you!

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etc

Probably not the best idea to use a vertical CR2032. The clearance is quite limited as a result of the sheet metal screening above the board in situ.

Some horizontal thru-hole holders seem to be a surprisingly good fit. I've attached a picture of one I found from an australian repairer.

17 seconds pause with a gray screen seems too long, unless the hard disk takes that long to become ready.
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You're right about the

You're right about the clearance, I checked and indeed it cannot be vertical.

I admit a interposer would not make such a huge difference. Maybe I'll just find some better holders!

 

I am not very much skilled with the Macintosh. The Miniscribe seems to be a bit old - sometimes it makes "banging heads" noise when power up. However I hear the drive seeking and then doing nothing - until I hear that click and the computer actually starts up. 

I have a Floppy emu coming so I should be able to remove many other variables. Could it be the HDD preventing the boot process? Wouldn't I get the floppy icon on screen? 

Thanks!

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You may want to also look at

You may want to also look at the BlueSCSI hard disk emulator for the SE.   It is a small reasonably priced device that emulates hard drives using an SD card.  There is an internal version and a DB25 external version.   There are several authorized sellers for these.  I am one of them and sell them on eBay, but others also have them.   See this site:   https://scsi.blue/

 

Jay 

 

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Thanks Jay! I might be

Thanks Jay!

 

I might be mistaken but I thought the Floppy emu could also emulate an HDD? Still, for the price, it might be nice to have a "fixed" HDD in those macintosh. Thanks for mentioning.

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Hi Tony,   They can, but they

Hi Tony,  

 

They can, but they are external and work over the floppy drive port.   Bluescsi connects to the SCSI port and is a little faster.   

 

J

 

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Indeed a good solution for a

Indeed a good solution for a dead HDD, you can tuck it inside the case and happy days, I agree. Thanks for mentioning!

 

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To update: the issue was with

To update: the issue was with the ADB chip. It was preventing the system from booting (also preventing mouse and keyboard from working). Once replaced, all was good.

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I made a repair video of this

I made a repair video of this Macintosh SE, I hope it's ok to link it here:

 

https://www.youtube.com/watch?v=e0DJYUwJMFw

 

Let me know what you think!

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Nice video!Note that the

Nice video!

Note that the flyback transformer (LOPT) on the SE has a bleeder resistor, so you usually won't hear any snap when discharging the CRT's second anode. Earlier models had no bleeder and could remain charged for days. It's still a good practice to discharge the tube if you need to remove the anode cable.

As far as danger to life is concerned, I would have put the warning on the segment with the PSU under test with its cover removed. The primary side smoothing cap can supply a lot more heart-stopping current compared to a 9" CRT. I know you don't touch anything near it on the video, but it's a missed opportunity to put safety risks in perspective.

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You are totally right - I

You are totally right - I forgot :) I am totally aware of the dangers but it's Youtube, I should have added a warning there too. 

 

I suspected there was a bleeder but as you say, better safe than sorry! Thanks for mentioning.

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I've published part 2 of the

I've published part 2 of the repair video, let me know what you think! :)

 

https://www.youtube.com/watch?v=siR-XEheM90

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Part 3 is finally online -

Part 3 is finally online - this is the last part! :)

 

https://youtu.be/dl6pi7J_ALI

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Agreed on the BlueSCSI.  I

Agreed on the BlueSCSI.  I just got one for my new (to me) Mac SE & I love it!  I designed a bracket to mount it in the PDS accessory opening on the back of the case so it sits flush with the back of the case when closed & the SD is easily accessible. 

 

 

 

For the battery, I 3D printed a small holder for a CR2032 & soldered it right to the board in place of the Varta.  It's not the most elegant install but it works.

 

 

 

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SCSI drives can sometimes be

SCSI drives can sometimes be formatted with variable number of spare sectors to use for relocation. But at a higher level, bad sectors (or rather the clusters that contain them) can be assigned to an invisible, unused file so they are not treated as available to be used. I believe that is what HDT is doing when it provides for additional remapped sectors.

All software RAM tests suffer from a common problem which is that the software and OS must run out of the same memory, so not all of it can be tested. In some cases swapping SIMMs around and rerunning the tests allows to cover the other parts of the RAM.

The "Disk Rejuvenator" is not really to do with hardware errors but with how the OS directory on the disk is stored (the documentation says it fixes "command not found" problems).

Any classic mac user needs a list of error code meanings: https://www.cs.cmu.edu/afs/cs/user/lenzo/html/mac_errors.html

-72 is "bad data mark checksum". This refers to the GCR encoding of sectors on the floppy disk.

Mold is definitely a big issue, and under some climatic conditions it can spread. If it's growing on the cookie it certainly has spores on the fabric pad in the disk case as well.

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Mac SE restoration

Hi - I also have a Mac SE I would like to get working again.  It is a 1989 model (manufacture date was Sept 10, 1988) and I am the original owner.  For the last 32 years - until recently - it has been in a sealed bag and that in a sealed box.  I pulled it out the other day and tried to fire it up, and while the motherboard and CRT seem to be in good working condition, the floppy and hard drive are not working.  The machine chimes on, image on screen is good, and I get the 'searching for disk' icon. 

 

Upon closer examination, the motherboard shows no sign of leakage or corrision.

 

Ok, to the question now.  After doing some limited research, it appears that to replace the storage I have three options (that my limited skill set knows about):

  • BlueSCSI.  It looks like I can pick one of these up for around $45.  They appear to have limited read and write speeds, but given this might not be the bottleneck in an SE, it might be fine.
  • ZuluSCSI.  Around $60 with better read/write speeds, but I'm not sure it will work.  I e-mailed the company with the particulars but got no reply.  I'm guessing they only reply to larger corporate folks.
  • Floppy EMU. Seems like a nice little device that would work well, but at $110, not sure I want to spend that kind of cash for my 'first time out'.  

 

I would welcome any comments or feedback - or anything else to increase my limited skill set.  Thanks for reading my post.

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A BlueSCSI will perform

A BlueSCSI will perform admirably in an SE. Even though it's not as fast as the ZuluSCSI or BlueSCSI version 2, it will still be much faster than the original hard drive. A FloppyEmu would be better if you planned to get into Apple II machines or earlier, pre-SCSI Macs.

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Thank you for the information

Thank you for the information.  I have ordered a BlueSCSI - of course in this chip-shorted world, the only one I could find in stock with a case (I wanted an external one with a case) was a BlueSCSI version 2.  Anyway, thanks again.

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The floppy drive may just

The floppy drive may just need to be cleaned and lubricated.  A lot of those Sony 3.5" mechanisms the original lubricant over time dries up and hardens and then things don't move like they should.  The other thing that happens is the eject mechanism gears turn brittle and fall apart.  Luckily replacements are available for those.

 

The hard drives, especially the early Quantum mechanisms often found in older 68k Macs often have similar problems -- "stiction" where the head gets stuck to the platters because the lubricant on the platters dries up over time.  Sometimes you can unstick those drives by giving them a smack...  However...  this is usually a temporary fix at best and it doesn't always work and sometimes completely breaks the drive...  so do it at your own risk.  I've heard of people opening those drives and re-lubing them, but unlike the flippy drives, I wouldn't recommend it.

 

 

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Thank you

As per your advice, I partially disassembled the floppy drive and cleaned and lubricated it (after watching a few videos).  The good news is the drive now reads perfectly and I can boot the machine from it.  The bad news is it can't eject a disk because the infamous 'orange gear' inside of the eject motor housing was crumbled in pieces when I opened it.  For now, it's not a problem because I can manually eject a disk with a sturdy paper clip.  Later I can buy some replacement gears.

 

So, on to my next question: when my BlueSCSI arrives next week, now that I can boot from floppy, can't I just initialize the new 'hard drive' directly from my Mac - like I would have had I installed a new SCSI drive back in the day? I guess what I'm asking is will my Mac see the BlueSCSI just like it would see any other uninitialized SCSI drive? 

 

Again, thanks.

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Glad to hear the cleaning and

Glad to hear the cleaning and lubrication helped.  Unfortunately the eject gear falling to pieces is virtually every single one.  As you mention, at least it is relatively easily fixable with a replacement part.

 

Those Sony drives, despite the issue with the gears are actually pretty reliable for being so old all things considered.

 

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For the SE I just did, I put

For the SE I just did, I put a right-angled female header on the BlueSCSI (has to be soldered to the bottom of the pcb!) and plugged it directly into the logic board. Very tidy that way.

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