Zombie 'puting: resurrection of a 1500HD

[leeb]

I originally wanted to acquire a 2810HD like I had when I got out of the Navy, but found this on ebay and got it for most-of-nothing...

SO...

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

Start

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... :D

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...:dontgeti:
and....
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!:dontgeti:

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!)

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! :mrgreen:

THIS THREAD has been moved to a blog... but feel free to add comments/suggestions/HELP here too!

 

[EddieDX4]

I have a 1500 HD also. Have had it for sometime now, and bought it with a bad HDD and FDD. I'm going to attempt to fix the FDD first, and see if the HDD is recoverable (hopefully it's not a hardware problem).

Keep us posted on your ordeal.

 

[leeb]

I have a 1500 HD also. Have had it for sometime now, and bought it with a bad HDD and FDD. I'm going to attempt to fix the FDD first, and see if the HDD is recoverable (hopefully it's not a hardware problem).

Keep us posted on your ordeal.

Feel free to add your 'woes' to the blog! I will do (or at least say) what I can to help out!!!
I got a 2810HD while I was in the Navy and just 'have a thing' for the design... and the 1500 and 1800 are the same case (tho the 1500 is CGA)! Even now, I believe it is one of the nicest looking machines EVER made...

Well, I do! :D

 

[EddieDX4]

Feel free to add your 'woes' to the blog! I will do (or at least say) what I can to help out!!!
I got a 2810HD while I was in the Navy and just 'have a thing' for the design... and the 1500 and 1800 are the same case (tho the 1500 is CGA)! Even now, I believe it is one of the nicest looking machines EVER made...

Well, I do! :D

I agree... Whoever at Tandy came up with the design was thinking ahead of their time. It was sleek, clean, simple.

 

[leeb]

I agree... Whoever at Tandy came up with the design was thinking ahead of their time. It was sleek, clean, simple.

Now...
If only I could make room for a CDROM! :mrgreen:

Ya know... that makes me think...
(wondered where the smoke came from! )

 

[leeb]

Well, the 2810HD arrived Wednesday, and it taught me a couple of things...

The one pertaining to this thread (and the blog) is that the 1500HD MAY have an issue with the charging circuit.
(EddieDX4, or anybody else with a 1500, feel free to confirm this IYDM!)
On the 1800 and the 2810, when the battery is disconnected and the P/S is on, the charge light BLINKS yellow. My book on the 2810 says this IS NORMAL.
However, the 1500 does not do that. It DOES a) come on solid when charging (the battery is in place), and b) goes GREEN when it (supposedly) is fully charged. What it DOES do is go OUT completely when the battery is removed.

AFAIK this is ABBY-SOMEONE.... That's right. Abby NORMAL.
Figuring out the charging circuit right now tho, is a LOW concern... as long as it charges I dont give a RAT if it blinks with the battery loose... in fact I like it better that way! :mrgreen:

But if it isnt right, I still want to fix it... :D

BTW...
It is actually a PANASONIC design... 'Custom made for Tandy/Radio Shack' Uh huh... the 2810 IS the Panasonic CF-270 Business Partner.
But that's okay with me! More potential 'spare parts'! :D

 

[EddieDX4]

Hmm, I'll have to confirm this but I have a different problem. I have 2 batteries and I've left each in as long as a full 24 hours with the charger plugged in and the light remains amber. It never turns green.

However, I noticed that 1 out of the 4 contacts on the 1500HD is corroded, so i attempted to "file" out some of the corrosion in case this was the issue, but that made no difference.

The batteries have no charge whatsoever and unplugging the charger after the 24 hours cuts all power to the laptop.

 

[EddieDX4]

I just tested my 1500HD with no battery in but plugged in. No blinking light. No lights whatsoever. Once I turn it on, the power LED comes on, but the battery one remains off.

 

[leeb]

Okay, thanks! That confirms what I needed to know...
BTW... the 'wide' ones actually supply power to the battery. The other two are 'sense' connectors that tell it when the battery is getting warm... presumably = charged...
But I know from actual experience that these batteries have 'fuses' inside that will break if the current (charge or discharge, I presume) gets too much... that may be why it doesnt ever go green...
What you can do to test is to put a jumper between the 'narrow' ones and see if you're getting power on the wide ones.

You most likely are tho... Mine had a bad fuse (1.25a) that was for the charging circuit. Until I fixed it, it would always say the battery was charged (go green) even when it was < 1v.
It DID seem to 'trickle-charge' tho while it was green. My battery (admittedly TRASH) SLOWLY started getting a charge even while it said it was green...

Im willing to bet its the batteries.

And thanks for the info! :D
Edit:
Well, that tears it!
I found a PDF of the 1500 user manual, and it says that it does NOTHING unless it is charging OR IS charged. (yellow or green). NO BLINK.
So, its NOT broken.
And I like it that way! :D

 

[leeb]

OFFICAL TITLE CHANGE: from 1500HD to TANDY Laptops!

OFFICAL TITLE CHANGE: from 1500HD to TANDY Laptops!

Edit:
I am offically changing the title of this thread to TANDY Laptops... since I am now 'playing' with 3 OF THEM!
Besides, the 1500 is almost 'roadworthy' now... give-or-take a new battery... or two! :D
Required materials are coming for work on the 1800hd, and the PDF of schematics for the 2810hd have already been saved... in about 5 different locations! :shock:

I think once I get home, I will do a resistance-check on the battery connections of both the 1800 and 2810 to see if there is something resembling a short on the 2810...
----------------------------------------------------------------------
I took my own advice (IMAGINE THAT!!! ) and did some 'charge-voltage checking'...

The 1500 shows 'around 12v' all the time. IF I short the 'sense' pins (the narrower set), it claims the battery is charged. *** I believe this is PROPER operation for this design. The depleted battery would drag this 'stable voltage' down and until it returns to this level, the 'charge light' would be active. THEN the 'charged' (green) light would be active. ***
(ALL PRESUMPTION on my part of course, as I have no schematics to confirm it)

The 1800 shows a small amount (< 1v) UNTIL I apply the 'jumper'... then it shoots up to around PS input voltage until the 'jumper' is removed. *** This I believe is the PROPER operation ***

The 2810 shows approximately the same small amount as the 1800, but IT DOES NOT CHANGE with the jumper applied, and after a short time will BLINK RED until the jumper is removed.
I believe this to indicate a 'perceived internal short of the battery', as I have NEVER seen that 'blinking red' before...

So, as long as the 1500 shows approx 12v at the WIDE-PLACED battery connectors, it is likely OK! :mrgreen:

 

[leeb]

Some early results

Some early results

are in, and they are good AND bad.

THE GOOD -------------------
The pinout/edge connections are EXACTLY right center-to-center! nfire:
The right edge-to-first-pin dimension is EXACTLY right! nfire:

THE BAD ---------------------
The left edge (pin1 end) was off... I believe by ONE 'PIN CTR-2-CTR WIDTH'... :blush:
So, I will have to redo the board to eliminate the extra... and allow the 'tracer' to redraw it.
On top of that (literally!), the upper edge is almost 3/16 - 1/4 inch taller (a guess since I dont have a ruler available) than the 30-pin unit that WOULD fit... if it had 35 pins... I DONT KNOW yet if the extra height is going to be a problem, but

IF THE CHIPS IVE SELECTED are the width I believe they are, this extra height is almost ESSENTIAL.

How to find out?
I will make a cardboard 'board' and see if it will clear the cover. IF NOT... I will have to select a different chip...

But overall, things are going quite well!

 

[EddieDX4]

I can totally see you screaming "IT'S ALIVE!!!!!!" all maniac-like when you succeed.

Keep the logs coming. If anything, this is at least revealing some great ingenius ideas that may apply across the board.

 

[leeb]

Well folks, its gonna be CLOSE!!!

Well folks, its gonna be CLOSE!!!

I can totally see you screaming "IT'S ALIVE!!!!!!" all maniac-like when you succeed.

Keep the logs coming. If anything, this is at least revealing some great ingenius ideas that may apply across the board.

The design of the board is now PERFECT!!!

EXCEPT...

The height has GOT TO BE REDUCED!!! The extra height must be reduced by ALMOST HALF! :shock:

I dont know if I can get the 400mil DRAMs to fit on this narrow board.... but it will be interesting to try! 8)

I guess I forgot to mention that I have to find memories that will fit? :roll:

 

[leeb]

We learn by doing...

We learn by doing...

(Modified from original)
I have learned that the 424260 memories I intended to use simply are too 'complicated'. There is not enuf room on these thinner-than-normal boards for all the traces...
Which led me back to the 4c4001s that are on the 30-pin boards.

The only problem with THEM is that they have 9 address lines and only 4 data lines. I must use BOTH ICs at the same time to get the 8 data lines on one board.
No big deal, but the 1500/2810 slots seem to be designed for 256Kx8 chips X 4...

So now the board is ready but the design will depend on the chips I use...

Lays or Doritos? :mrgreen:

 

[leeb]

Something interesting...

Something interesting...

Ive noticed something interesting...
I have recently attempted to format a: /s on multiple FDs... (HD of course!)
and...
EACH AND EVERY ONE fails 'modifying BOOT'...
UNLESS I format it on another machine.

These disks can be read/written to ONCE another machine formats it...

It is not the floppy drive as I have tried multiple drives.
There must be SOMTHING wrong with the controller/lines or interface items...

Exactly what, I have yet to discover, as I have may irons in the fire now.. :D

 

[EddieDX4]

Ive noticed something interesting...
I have recently attempted to format a: /s on multiple FDs... (HD of course!)
and...
EACH AND EVERY ONE fails 'modifying BOOT'...
UNLESS I format it on another machine.

These disks can be read/written to ONCE another machine formats it...

It is not the floppy drive as I have tried multiple drives.
There must be SOMTHING wrong with the controller/lines or interface items...

Exactly what, I have yet to discover, as I have may irons in the fire now.. :D

What happens if you try covering the HD hole on the disk and formatting in 720k format? Or, if you happen to have an actual 720k disk..

Just curious to see if there's something odd going on with the access to the first few tracks of the disk, enhanced by the smaller HD track writing.

 

[leeb]

I dont believe it!!!

I dont believe it!!!

IVE BEEN STONED!!!

SOME disk I got from the 2810 purchase (or the WFW3.11 disks) had the STONED3 virus on it/them!

NOW I have to go thru ALL of them again and clean them!

That is likely where the format error came from! Will advise after the fact.


SURE GLAD dos 6.22 could do something about it! :wow:

YEP!!! DATS ZIT!!!

Thats what it was!!! Amazing.:sarcasm:


Oh, btw...
It still doesnt know the difference between 1.44 and 720. Covered the hole for 720 and it still formatted 1.44.
Apparently the sense isnt doing anything?

NOW I gotta check my ME system to make sure it doesnt have the dang thing too!
(The XP machine no-gotta-floppie)
:evil:

 

[EddieDX4]

Hmmmm... At least it wasn't the Monkey virus. :-D

Regarding the HD/DD issue, did you cover it with a dark/black piece of tape? If it's clear or allows light to go through, it will likely continue to treat it as an HD floppy.

You could use the proper parameter with the FORMAT command to force it to do 720k.

EDIT: Although, at this point, it's a moot point... hehe... But, I figure, to test for the presence of the sensor.

 

[leeb]

Actually on the 3.5in drives it is a mechanical sensor (pin switch) instead of an optical one.
But yes, it was covered with electrical tape and still claimed it was 1.44

I now have a nice 540Mb drive.... just waiting for a WORKING machine to put it into! (other than the 1500 which would require a rewrite of the BIOS and I DONT WANNA... rite now! :D

 

[EddieDX4]

Actually on the 3.5in drives it is a mechanical sensor (pin switch) instead of an optical one.
But yes, it was covered with electrical tape and still claimed it was 1.44

I now have a nice 540Mb drive.... just waiting for a WORKING machine to put it into! (other than the 1500 which would require a rewrite of the BIOS and I DONT WANNA... rite now! :D

I could've swore I came across drives using an optical sensor, in the past.. Though I can see how the ones used in the Tandys would have been mechanical.

Speaking of HD's and BIOSes... Could a dead CMOS battery be the reason for my 1500HD not recognizing the HD? This whole time I figured the BIOS on these machines was hard-coded with the hardware they came with, but if they actually have different drive type selections, maybe that's why mine isn't seeing the HD?