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Thread: Advanced Technologies - LCD Portable 286 from 1988

  1. #1

    Default Advanced Technologies - LCD Portable 286 from 1988

    This is my first thread on this forum, so I wold like to say Hi to everyone.
    I'm from Poland, so please be tolerant in case of my spelling. I own LCD Portable AMD 286 from 1988. This computer was bought as new by my grandfather, and I would like to bring him to life. Below i put image how it looks like, on this image case is very dirty because I made photo just after i found him in the garage.
    DSC_1265.jpg


    When I'm trying to turn this PC on, the power supply unit starts normally, fan in PSU working correctly, screen backlight is going bright, but nothing is displayed Diodes on the keyboard doesn't light up. System speaker is connected, but there is no sound (beep).
    After turning this PC on, PSU is squeak quietly. So I decided to open the cover. Voltages on the PSU output are fine, I'm only not sure about plug that is conneted to the Graphic Card. Graphic Card has their 4-Pin plug, just like shown on below image...
    11.jpg

    I checked voltages on this plug, white wire - 230V AC , on the red wire - there is (as I remeber) about 9V DC. I'm afraid that 230V AC is not good value and it could destroy the graphic card or even more ... When this plug is disconected from graphic card, PSU starting to squeak louder, when I touch white and black wire for measurements with the multimeter, squeaking is quiet (similar like when it's connected to graphic card). I opened the PSU cover, inside I found below converter:
    2222.jpg

    It looks, that this converter was added to PSU additionally, when I disconnect yellow wire (5V DC) - PSU stops squeaking. I decided to replace electrolitic capacitors in this converter - without any results, there is still 230V AC on the white-black wires, and the squeaking is still audible (same level).

    Below I attach graphic card image, I have two questions about this card:
    1. What should be the voltage to supply this graphic card (on 4-pin plug)?
    2. There is a switch on the graphic card "blade", it has two positions, I check both - without success. what is the function of this switch?
    DSC_1295.jpg

    I have also one question about 2-Pin plug shown on below image:
    4444.jpg
    This wires are going from PSU to the front of the PC. I did not disassemble PC to check where it is connected to ( I supose screen or power diode). Power diode on the front did not light up - so this is my favorite. Voltage between this wires is about 3V DC, but as you could see on the image, the wires are crossed. I did not try to change them. Is it ok, or i have to change it?

    Thank you in advance for any help.
    Last edited by toper-utl; December 6th, 2018 at 10:26 AM.

  2. #2
    Join Date
    Oct 2018
    Location
    Fontainebleau, France
    Posts
    8

    Default

    Hello toper-utl,

    Your computer looks very cool! I hope you will make it work.

    230V on a graphic card is for sure not correct and will most probably damage something if it is plugged. (Beware of yourself too ^^).

    The converter you found quite looks like a linear power supply (i.e. transformer + diodes + capacitor). If you see 230V on the output, then I suspect it is the transformer, not the capacitance, which is shorted. Can you check if there is continuity in the primary, in the secondary but not between both. If there is, the module is probably damaged and you should probably throw it away and get another one.

    Also, if you unplug the graphic card and start the computer, can you hear the floppy drive or the hard drive making noise?

    felixzero

  3. #3
    Join Date
    Sep 2017
    Location
    Porter County, Indiana, USA
    Posts
    104

    Default

    That unit is quite dirty and yellow. Have you tried cleaning it and giving it a good coat of retrobright? Maybe in the process of removing all the plastics you could find whats wrong

  4. #4

    Default

    Quote Originally Posted by felixzero View Post
    Hello toper-utl,

    Your computer looks very cool! I hope you will make it work.

    230V on a graphic card is for sure not correct and will most probably damage something if it is plugged. (Beware of yourself too ^^).

    The converter you found quite looks like a linear power supply (i.e. transformer + diodes + capacitor). If you see 230V on the output, then I suspect it is the transformer, not the capacitance, which is shorted. Can you check if there is continuity in the primary, in the secondary but not between both. If there is, the module is probably damaged and you should probably throw it away and get another one.

    Also, if you unplug the graphic card and start the computer, can you hear the floppy drive or the hard drive making noise?

    felixzero
    Thank you felixzero for your advices.
    This converter is powered with only 5V DC, so there is no way that shorted pri. and sec. inside transformer could "transfer" 230V to output. There are only 4 wires connected to this converter --> Two of them are supply (Ground and + 5V DC), and rest two are outputs (Ground and 230V AC). It's looks like, that this converter is added to PSU to give some specific Voltage to the graphic card, but the question is how many Volts it should be (DC or AC)? Of course I will check if this transformer is shorted, but the major question is about Voltage required to powering Graphic Card... I'm uneable to find this information in any source of knowledge. When I get this information, I will be able to eventually buy other PSU as a replacement.

    There is no HDD inside of this PC. There are only two floppy drives - 3,5 and 5 1/4". When I turn on the computer with inserted Graphic Card, after about 10 seconds one of the floppy drives is trying to read the dics (drive is empty). When I remove this 4 Pin plug from Graphic Card and turn on PC - situation is the same -> after 10 seconds floppy drive is trying to read disc. I have to check if there will be the same situation after completely removing of Graphic Card.

    I will be realy thakfull if somebody could answer - how manny Volts is required to powering this Graphic Card.

  5. #5

    Default

    Quote Originally Posted by IBMAT5170 View Post
    That unit is quite dirty and yellow. Have you tried cleaning it and giving it a good coat of retrobright? Maybe in the process of removing all the plastics you could find whats wrong
    As i wrote in the begining of my first post, photos were made just after finding this PC in garage after about 20 years of storage. Now this machine is clean and shine. Only yellowish colour is still visible

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