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Zombie 'puting: Resurrection of a Tandy 1500HD

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I originally wanted to acquire a 2820HD like I had when I got out of the Navy, but found this on ebay and got it for most-of-nothing...


This thread (now blog) will chronicle the effort(s) to bring this beast back to working order, and beyond!


Got it out of the box and, of course, it didnt do... anything. Yeah, big surprise. I had been told it didnt have a power supply or anything 'useful' other than it was in 'one piece'... which could be considered a good thing.
Once I found a PS that produced adequate power (9.5 is what it wanted but accepts 12), I plugged it in... and nothing.
Silly me... Tandy in their infinite wisdom changed the 'standard' and used a NEG-CENTER for the power connector... end swapped, problem resolved. Sort of.

At power-on it screamed some (as yet unknown) beep code(s) and the screen looked broken. So were my hopes.
The battery claimed to be fully charged even tho I KNEW it was DOA, and NEVER attempted to charge when it was reinserted... definately a curious condition.
Presuming something terminal was preparing it for the dumpster, I entered the belly of the beast.
FIRST thing I did was... fight to remember how to open it! (The case is almost exactly like its better-muscled siblings so it didnt take long) I looked for and checked all the fuses I could find (which were 4). There were (2) 2A-ers, one 1.25A, and one 0.325 (or something equally funky). The 1.25A fuse was dead... no continuity across the connections. Since the machine DID attempt to do SOMETHING even with this bad fuse, and knowing as I do how detrimental pissy batteries are to charging systems, I suspected this fuse was preventing the normal charging sequence.

Reconnecting everything and powering up brought the screaming and bad screen again... Sigh.
Power off.... power on.
BEHOLD! a clear screen and BIOS info appeared! Perhaps the CMOS battery is to blame....
Well, at least the main system was not dead...

Breathing life into dirt

Well, so it at least tries to boot... a good thing!
The next step is to attempt to boot a DOS of some-sort and see how things go.
(Since the CMOS battery is presumed dead, the hard drive is not attempting to start up. Hoping the drive is not at fault, I must attempt to boot from floppy first...)
I created a boot disk from an ME CDrom,
which took some doing--my HD floppies were used to being 720k CP/M disks...
the floppy drive will not accept a floppy...

Well, at least I already have the thing torn apart... we delve a bit deeper. Removed the floppy drive and opened it up to find....

the upper head was hanging down inside the drive!
Being the 'tinkerer' that I am... I removed the broken head and put the drive back in, hoping that it only needed to boot from the first side. (Foolish I know, but at that point... why not?)

At the floppy boot point, something that sounded like a jet engine spinning up... and boot failure.
Again, no big surprise... but, once I pulled the drive back out I realized that the spindle belt was too loose to spin the disk even if it COULD read from only one side!

So... Phase 2 will have to wait until I can acquire/connive/frankenstein a floppy drive into the beast!
(I have such a thing coming from ebay now... I hope!)

A bit of Inspiration...
I had an idea... I had an old 1.2gb AMD board lying around, and a beast that had a dead CMOS battery...
I took the 2032 battery holder off the AMD board, and replaced the 1500s CMOS battery with the holder, effectively allowing EASY replacement of the battery whenever necessary!
** There is a good chance that the 2032 doesnt put out enuf power to last very long... but for now, it still shows a full 3V when the PS is disconnected! M-I-C... K-E-Y... M-O-U-S-E indeed! BUT IT WORKS!

Stupid Thing To Do... #1 (a.k.a. how to break it before its fixed...)

A couple of days ago I made the mistake of plugging the PS into the machine before plugging it into the wall. Didnt notice anything unusual then, but yesterday I tried to power it up again and got... nothing.
Recheck of the fuses showed that BOTH 2A fuses were gone.
So, the undisputed expert at MICKEY-MOUSE connived some mini-fuses (like those in christmas lights) of the proper values into place on the system board. Amazingly enuf, now even the battery attempts to charge, and the charge light shows yellow (as it should) instead of green (full charge)...

Wont do THAT again.... this week!

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Updated April 17th, 2010 at 07:06 AM by leeb

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