Monday, December 17, 2018

TOSHIBA T1000LE Repairs




YEAR: 1990
INITIAL PRICE: $1799




SN: 10016686

The Toshiba T1000LE was one of the first laptops to include both a hard drive and a Ni-CD battery. Previous laptops did not have enough power to run a hard drive from battery power (exceptions include the Toshiba T1200, which had a proprietary 26-pin JVC hard drive, and the Macintosh Portable, which used a lead-acid battery, instead of a Ni-CD).

I bought this computer at a reasonable price for $20 from a local sales site. it came with the original brick adapter at 1.7 Ah. The seller was stating that it does not power up but it did power up about 10 years ago. :)



I plugged in the brick adapter but nothing happened, except for a very short flick of RED of the DC IN LED. The flick is so short, you would not notice it, if its not total dark in your room. Clearly there must be some kind of short circuit in the battery pack or some dead capacitors.

First you need the laptop maintenance manual. It can be downloaded from here

Thank you, www.minuszerodegrees.net!

  
This is how the inside of the machine looks like


If you can see in below pictures the capacitors leaked everywhere and definitely need replacing.

You need 2X10V 220uF, 2X16V 220uF, 5X25V 220uF, 2X36V 220uF 1X6.3V 1000uF

Under the keyboard:


Under the screen:

 

As you can see the caps are bloated underneath even though they look like new at first glance. 

I had no chance to un-solder the old caps from the motherboard so I cut the connectors and resoldered the new ones as shown
All capacitors are changed

First boot:

I had plugged in the AC adapter and it seems the DC IN LED had started lighting RED. The unit now powers up but only for 3 seconds and then it shuts down. :(


I had searched on the net and this particular Toshiba runs only if there is a good battery installed. I have no RTC battery installed or sub-battery but I was able to change the cells in the battery pack.

Now it power's up but i have some contrast issues. In order to fix those I had recapped the display as well. 


It looks like this is a success and the system is back to life!!!



Thursday, March 15, 2018

The Amstrad ALT-286 - Repairs, FDD Not Working, Battery Damage



The Amstrad ALT-286 is a very nice machine, its a mix between the TOSHIBA T3100/20 and the SHARP PC-4500.

It shares same technology like the two mentioned above but the display its superior due to the fact it came on the market almost 3 years after the Toshiba and Sharp. Even if it was more budget oriented the computer has a lot of features and the quality build is impressive.

I got this computer from a local sales site and the computer was stated as working. The amount requested was 699 LEI, that means in EUR 155. I called the seller and he was OK to sell it for 40 EUR. The original post:



Short technical description:
Computer: ALT 286
Processor: 80286
Screen: VGA LCD 640*480 Pixel
Reverse by programming plus contrast and brightness switches
Graphics: Cirrus Logic
Memory: 4x 1024 KB Max
Harddisk: 20 to 60 MB
FDD Drive 720 KB FD-235HF
Extensionslots VGA
ISA
AT Keyboard
FDD Floppydrive
System: DOS 3.3 and DOS 5.0
Printerport Centronics
Serial Ports 2x9 Pens. One for mouse
Weight: 7 KG


Issues:

The Computer had better days, the HDD spins up but OS is not found, and the FDD is not working for sure as it has a very unlikely sound when booting and it does not spin the floppy disk. I will take apart the computer these days and I will replace the HDD and the FDD unit. The FDD unit can be replaced but there is a custom mod you have to do on the Floppy cable. I found an interesting article of someone that replaced the original unit with a standard one. I will start working and get back to you with the details.



Step 1 Disasembly

Remove the screws from the bottom \ back and aside.

Bottom view


Step 2 Remove top cover

To do this you need to have your screen in OPEN position and then just lift the top cover from the bottom and put the cover on a side like in the photo. The display cables are pretty long so you can leave it like that or remove the cables to fully take apart.

Inside #1


Step 3 Remove stuff

EXTENSION MODULE

For this you need to remove the 4 screws in the picture and just lift up the socket on the right top of the module. (this is not mandatory but you need space to remove the FDD)

Extension module\ Bios chip (on the back)
View on RAM and BIOS (the sticker came off, don`t get it into the light as its UV sensitive and it will erase data\I had put a black sticker on that)

REMOVE FDD UNIT

Remove the 5 screws and lift up the FDD unit. 

Floppy Disk Removed

REMOVE ALUMINUM COVER

Next part is to remove the aluminium cover (note that this cover has also the role to spread the heat of the chips)


Battery leaked on the MOBO :(


Even if the battery looks in sharp condition you have to remove it. If it hasn`t leaked it will so just replace it or cut it off. I just removed it cause I use this computer rarely so I just don`t care the setup will forget the HDD config or the clock...


REMOVE METAL FRAME

Next part is to remove the metal frame like in the picture below:

Metal Frame


BATTERY DAMAGE REPAIR

Battery damage on mobo
I had used some Isoprylic Alcohol to clean the damage and vinegar ti neutralize the acid area.

Now this looks better! Lets get some soldering done!
Nice and Clean
The capacitor seems fine, so I just resoldered but its legs were damaged so I used some extra wire... a lot of extra wire :)

You have to agree it looks artistic...  ;))) be careful on the polarity (the capacitor has a black mark for negative)

Now lets get back to the FLOPPY part 


Basically you need a standard 3.5 FDD, I got one with the DS jumper so for me its very easy to make the mod. Basically I just have to remove 5 7 9 11 wires stated in above diagram and get the +5V on the new FDD unit.

IF YOU DO NOT HAVE THE DS OPTION

Cut 10 and 12 and reverse 10-12   \ 12-10

OLD VS NEW Floppy design

I was able to change the plastic front ornament from one to another, they are both made by TEAC company.
New FDD with the old grey front ornament
I think the picture above is very descriptive and for those who are technical people will manage easy.
Where my hand is is the connector that fits the mobo.

1 is the green wire \ use 11 for +5V and cut down 5, 7, 9, 11

I had put some isolating tape just to make sure the wires won`t touch something inside the computer.

Use any tape you have and place on both sides

Now Place the red wire on the +5V connector on your new Floppy Disk.
+5V on first inner pin


TESTING

Now place the FDD cable and the pin on +5V and boot up your PC!


MS-DOS 5.0 is now loaded!

NEXT STEP - Sit back and enjoy your vintage laptop!



If you have any questions, leave a comment.
Don`t forget to check out my museum`s Facebook Page and WebSite




Thursday, October 5, 2017

Macintosh Classic boot from ROM

The Classic is a unique machine, its the ONLY Mac that can boot an OS from ROM, Hold down command-option-x-o on bootup and it will start System 6.0.3 from the system ROM.


Wednesday, January 11, 2017

Sharp PC-4500

Sharp PC-4500 (4502)  


Restoring History




Manufacturer: Sharp Corporation (Osaka, Japan)
Release date: October 1987
Reference: PC-4500
Processor: Nec V40 at 7.16 MHz or equivalent (compatible with i80188)
Memory: 256 KB or 640 KB RAM expandable to 1.6 MB Including 1 MB of EMS memory
Display: CGA compatible monochrome LCD display (Backlit on models 4502 and 4521)
Storage: 1 or 2 floppy drives 3 "1/2 of 720 KB
Original Add
Or 20 MB hard drive according to models.
Interfaces: Parallel
1200 baud modem and optional external CGA
Software: Ms-Dos 3.2 Sharp

Particularity: Announced at Comdex Spring 1987 and marketed from October of the same year, this entry-level PC compatible PC is sold at a rather competitive price. The compatibility is good but the performances are not extraordinary. Note that it requires a version of Ms-Dos of origin Sharp to start.

3 versions ever existed:

PC-4501, 256 KB with 1 drive, LCD not backlit
PC-4502, 256 or 640 KB with 2 drives
PC-4521, 640 KB with 20 MB hard drive

My machine is a PC-4502, 2 Floppy disks, no HDD, back-lit display.






I got this machine 2 weeks back of the internet from a guy who said that it does not know if the machine is in working condition.

I am not very happy that I did not make any pictures how the machine looked when I got it but I can rate it a 5 out of 10.... and I will show you why.

GENERAL PROBLEMS:

1) The DC IN connector and wiring is missing.
2) The DC POWER BUTTON is missing.
3) The Floppy drives power connectors are missing. Power cables from the Power Supply to the motherboard are damaged and a few blown capacitors.
4) Missing bolts and screws
5) Cracked case
6) No AC Adapter



1) The DC IN connector and wiring is missing

This unit was completely butchered by someone who has no idea how electronics work. It seems the unit had some problems booting so someone just messed with the cables.

I had to rebuild the whole POWER CONNECTOR SOCKET!

Parts Used: DC Connector (from an old Toshiba notebook), piece of black thin plastic, soldering gun, poxipol-plastic welding, superglue and a LEGO piece :)

I started by cutting a square piece of plastic with a hole inside, same plastic as a credit card and fitting it into the unit with a drop of super glue, just so it would hold on when I will apply the other stuff. I needed this in order to mask the DC connector so when the unit will be assembled it will look like the original does.

Thin plastic square with a hole for the DC IN Connector
I needed to find a way to mount the DC connector a little higher so it will perfectly fit like on the plastic squares hole. 

So I found a permanent fix: LEGO! 

Bringing the base at the right size so the DC connector will perfectly fit the hole

I had soldered the + and - wires on the DC connector. THE SYSTEM BY FACTORY HAS THE CENTER PIN AS NEGATIVE. As I have a more modern Power Adapter I will use the center pin as + . 

DC Connector - Not Original one
Again I used plastic welding and fitted the connector on the LEGO piece.

DC CONNECTOR in place


2) The DC POWER BUTTON is missing

This unit has no power button so I googled but I can`t find much on this units insides to see what power button it originally had!!!

Lucky me I found this YouTube video of the inside of a PC-4521 machine....

So as you can see on the video the Power Button is similar with what you will find in an old laser pointer. And ...I still have some laser pointers in a shoe box in my storage.
I had cut the laser board with the some of the board around in order to fix the button on the original surface.





And this is the Output of 20 minutes of hard work :)



3) The Floppy drives power connectors are missing. Power cables from the Power Supply to the motherboard are damaged and a few blown capacitors


Looks like the one of the previous owner had tried to "repair the unit" by cutting half of the wires in order to power the motherboard from another power supply. I had spent some time figuring out what happened so here`s what repairs and fixes I had done:

Replaced marked in RED capacitors. It seems the power supply did not start because of those.
New wiring for the Floppy Disk units.
New wiring for the Floppy Disk units.

NOW WE CAN FINALLY TEST THE UNIT!



3.....

2...

1..
POWERS ON!
1 out of 2  Drives are only present. Date is 10 of September 1987




The weird thing is that the Keyboard is PASSED as test but no keyboard is attached at this moment...

There are some jumpers on this machine and I found some info on some forums... I really hope I can get the second FDD working so I can put MS-DOS 3.2 on 1 drive and some CGA apps on the other :)


I got the Jumper settings for SHARP PC-4500 and 4502 from a forum:

Link here.

"Here are the settings my PC4500 came with on the DIP switch bank on the bottom of the unit:

1 OFF
2 OFF
3 ON
4 OFF
5 ON

I would guess that one of these switches defines the presence of the second floppy drive and perhaps the presence of a full 640K memory card (I have both in this machine)."

The settings above suggest 640k memory and 2 FDD installed.





 


 

 

 










This restoration of the SHARP 4500 was a true success! :)