Building a Dual Floppy Macintosh Portable

[Patater]

As this Conner hard drive I have seems very noisy and about to die, I'd like to try building a dual floppy Macintosh Portable. I have never owned a dual floppy Macintosh, but I think it would be very nice. I love the sounds that the Sony floppy drives make. To have two of them going at the same time would be aurally delicious, aside from being useful.



I have two Macintosh Portable floppy drives with lower deck brackets. I don't know what the upper deck floppy bracket looks like. I can mount the floppy drive I have into the upper deck hard drive bracket, but it leaves the top of the floppy drive unshielded and exposed. I also need very long floppy drive mounting screws, as the floppy drive is a little less wide than the hard drive.





Even after I do get the mounting issues solved, there will be the problem of being able to insert floppy disks into the drive. The removable plastic face plates I have are from hard drive Macintosh Portables, so they don't have a slot for floppy disk insertion. It has been recommended that I use a steel template and a rotary Dremel in order to add a slot to one of my face plates, but I don't have a model to base my cut on. Where I do the cut might stray from the model, depending on where the floppy drive ends up after my upper deck mounting job.



So, in summary, I humbly request assistance from the army in procuring pictures of the original dual floppy Macintosh Portable face plate and the upper deck floppy drive bracket. Any help or advice is much appreciated.

 

[Patater]

Holy crap I finally found some pictures.

http://square.umin.ac.jp/~itoh/dual_fdd_1.html

That guy seems to be a serious Macintosh Portable nut. I wish I had found his page sooner.

This covers it for the removable faceplate stuff. I'm still looking around for information on the brackets and the best ways to rework this plastic.

 

[Patater]

Holy crap I found some more pictures.

http://square.umin.ac.jp/~itoh/dual_fdd_2.html

This guy is seriously awesome.

 

[Patater]

For those who don't read Japanese, the procedure is pretty simple.

I had taken off the floppy drive cover, but I didn't need to. I just needed to unscrew it so that I could fit it into the hard drive bracket with the floppy drive cover on (without the screw heads getting in the way). You just place the floppy drive with cover (but without the screws) into the hard drive bracket. The floppy drive cover has some bent metal on the side, so it keeps things snug. There are no places to put screws to secure the floppy drive into the bracket, but it seems to be enough snug as is.





So most of my problems were solved by this guy. There are some amazing people out there that the English speaking world just doesn't know about due to all of our search queries being in English. All we ever see of the Internet is the English stuff, but the Internet is truly global. I need to send this guy a big thank you after the project is done (so that I can send him pictures of it completed).

Now my only remaining issues are that I don't have another floppy drive cable and I have no experience putting holes in plastic in a professional way. I've only hot-knifed things, and they didn't look pretty afterwards. It'd also be nice to see how the original dual floppy Macintosh Portable did the upper floppy disk mount. Thanks all for your help.

 

[superpantoufle]

Here you'll find a floppy-driven Macintosh Portable web server with a how-to, in case it's of interest to you!

 

[Trash80toHP_Mini]

Why don't you replace the HDD with a Tray Loader CD?

That way you can attach the entire HDD Plate to the Tray, so that it'll pop in-n-out of the side when the CD cycles. You'll need to drill a hole for an open button, but you could use an LED for that and for the CD Access light!

Just a thought! }

 

[Paralel]

That website, running off of the Mac Portable, is impressively responsive.

 

[H3NRY]

Why don't you replace the HDD with a Tray Loader CD?

Won't fit. The drive bay in a portable is 3.5" deep, and a CD is 5.25" diameter.

It seems dual floppy Portables were very rare beasts. Portables were so expensive the few who could afford them weren't phased by the extra $800 for a hard disk.

 

[Trash80toHP_Mini]

OOPSIE!!!!!!!! :I

I was under the impression that it was a Half height 5.25" Drive Frame with a shock mounted 3.5" full/half height HDD in there. I must admit, I haven't pulled mine apart in quite some time!

 

[Patater]

The Macintosh Portable web server is interesting. I won't be doing that, though.

I am currently attempting to remove capacitors from my Portable's logic board. I used some flux to clear away most of the corrosion on the capacitor leads. There isn't much solder left. I took my soldering iron to the solder. But the solder won't melt! After I pick up some wire snips, I will try out the method documented here: http://450.servehttp.com/reference/caps/.

 

[Paralel]

It won't melt? I didn't think HighK solder was ever used in Mac/PC construction, especially not that far back, except for military/special application systems.

 

[Patater]

I suspect that most of the solder is directly under the capacitor: the rest has been mostly corroded away. I do see some solder on the outside, but I can't tell if it liquefies when I apply the iron. I don't think it is liquefying when I do apply the iron. This is less a problem with HighK solder (which I don't believe it is) and more a problem with an old corroded away solder joint, which I don't have experience reworking, yet. This is the oldest and most corroded circuit board I've attempted rework on.

 

[Paralel]

That makes sense. The oxides of the solder could very well have a far higher melting point making them immune to the thermal output of a standard soldering iron. That is an annoying problem, not enough heat it won't melt, too much heat and the board itself could be damaged.

I looked at the pics in the thread you linked. You're lucky the crappy caps didn't damage the legs on the nearby ICs. The caps in the Classic II I got not too long ago caused severe corrosion on the legs of several ICs, some as far away as a inch or more from the cluster of caps that went bad. I'm still debating whether to just ditch the logic board and get another one that is in better shape or try recapping/repairing this one. The external SCSI port is also crap, completely rusted.

 

[H3NRY]

suspect that most of the solder is directly under the capacitor: the rest has been mostly corroded away. I do see some solder on the outside, but I can't tell if it liquefies when I apply the iron.

The combo of solder and electrolyte produces a crust that doesn't conduct heat, so it's hard to melt the solder. There's also a couple of largish dabs of high temp epoxy under each cap. You are going to have to mechanically break the caps loose, I fear. I pry one of the corners up, then an opposite corner, then tear one lead off at a time. Fortunately my three portable boards are high quality and none of the pads came off the PCBs. Not so lucky with the LaserWriter PCB. The two caps right next to the trackball connector are so close to the connector they will be really hard to solder, but all my boards came out fine.

 

[Mac128]

I have no experience putting holes in plastic in a professional way.

You need a Dremel tool. It's a relatively easy thing to do. A starter kit should be enough to cut the hole and smooth the edges.

 

[Patater]

After I finished replacing the capacitors in this guy, I assembled it with the second floppy drive in place, connected with a self-made ribbon cable. The drives stack very well and are firmly in place. The upper drive could slide around if I forced it hard enough, but it is held in place with significant amount of metal squeezing metal friction.



Unfortunately, I am currently experiencing some undocumented sad mac action; this may be due to attempting to boot from a 9V battery by not having the battery cover on. My PowerBook 100 power adapter is dead, so I'll need to explore alternate powering methods. I have a replacement battery I'll be wiring up to try out tomorrow, but I don't have a charger for it yet.

By the way, if a PowerBook 100 adapter were available to me, could it be used to charge the Macintosh Portable without causing damage? I'm not familiar enough with the charging circuitry on the logic board (or possibly in the adapter) to say. It would also be nice to verify that the power adapter is a switching supply (as it feels pretty lightweight to me) or something else.

Thanks for the information, comrades. I enjoy learning about these wonderful marvels of engineering. Your help is much appreciated.

 

[Patater]

When the computer first boots up, it displays a funky pattern on the screen. This pattern goes away in less than a second. This is probably a typical memory check or something.



In attempting to photograph that, I discovered that some other sad mac codes are displayed before the final code is reached. These transient codes do seem to have a meaning, but maybe not one that makes sense; do they really matter or are they just noise before the correct code is shown?



I've found that a few different codes are displayed over my few attempts to start up the machine. The code is of the form "0030017xx:00001FFA", where xx can be one of 01, 38, 39, 3E. This major code 17 doesn't seem to be documented anyplace, but perhaps I just don't know how to read these errors. This is one of a few possible final sad mac codes.



Here is my best guess. One of the sad mac major codes shown is 14. I suspect that because I'm attempting to boot from the 9V battery, the power manager is complaining. Because there isn't much power available, the sad mac changes around until it reaches some equilibrium on some invalid code. I'll have to try with a new battery and power adapter to see if this not enough power guess is on the right path.

I'll be thankful for any guesses you have or recommendations for tests I should run.

xx(

 

[H3NRY]

Let's see... the PowerBook & Portable AC adapters are switching supplies, 7.5 V at various amperages. It seems the Portable's circuit can withstand 9 Volts input, because some people have run them from 9 V adapters without smoke. I haven't tried that myself. A PowerBook 100 adapter is fine for all purposes, including battery charging inside the Portable or in one of Apple's external battery charger trays. Just check to be sure it's putting out 7.5 Volts before you use it, as some of these old adapters have gone bad and put out more or less than the designed output.

The funky screen patterns are typical of a portable which is having power supply problems, either noise on the power busses due to failed capacitors, or problems with the power source. That's also what the screen of a backlit portable whose voltage regulator is failing looks like in the initial stages of failure. Can't help you with error codes. I suspect you're just seeing random errors due to flaky power.

Good luck bringing the old girl back to life!

 

[Patater]

It is great to know that the PowerBook 100 adapter is good for charging as well as running without the battery. It is also good to verify that it is a switching type.

There doesn't seem to be any special rigging required in order to run off of a 9V supply. I was able to boot into a sad mac with just the 9V battery. A lot of 9V supplies are meant to replace 9V batteries and so come with a 9V battery connector on them. The only 9V power supply I have is a 300mA type, so that won't do me any good on this. With my PowerBook 100 adapter dead, I'm now on the market for a compatible power adapter.

I had this 6V battery laying around, so I decided to hook it up. The cables for the Macintosh Portable battery didn't give me much slack, but I was able to hook it up and run the machine without the case on. This experiment should validate whether or not the sad mac is due to flaky power.



Unfortunately, I still get the sad mac. However, the code is pretty consistently 03001300:00001FFA. This $1300 code might be a CPU exception code, indicating that I'm receiving an interrupt too early in the boot process (as per myoldmac). That in turn might mean that an interrupt line is being permanently asserted. As I'm not sure which caps are in the interrupt path (if any) I'll just look over all my work again carefully and hopefully I'll find something.