Help me Identify some Hardware mods!

By RetroFletch

Supporter (13)

RetroFletch's picture

22-07-2019, 10:15

So i got this Panasonic FS-1A with a bunch of mods in it, some i have identified, reset switch and a switch that drops me into basic and ignores the rest of the built in software.

But there are two added LED's i dont know function of, and also a added chip with a potentiometer whos function i dont know.

It also seems one of these mods might have messed things up becaus im stuck in "Graphics mode" meaning i cant write normal text im stuck with the secondary characters like hearts, spades, circles, blocks and so on.. and ive tried every button combination i can think of but cant get it back to normal text.

I did my best paint illustration on here, hope its clear enough. Cheers

Also might guide someone in future who wants to add a reset button and such..

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By gdx

Prophet (2858)

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22-07-2019, 11:55

S1985:
Pin 71 is /CAPS mode
Pin 72 is /KANA mode

So I think these signal are ussed for the LEDs KANA and CODE.

M60002A-0108FP:
Pin 33 is the signal for the slot 3-2.

The switch is probably to disable it to remove firmware.

I am interested in the Reset button. Is there anything else to add that push button?

By RetroFletch

Supporter (13)

RetroFletch's picture

22-07-2019, 12:51

gdx wrote:

S1985:
Pin 71 is /CAPS mode
Pin 72 is /KANA mode

So I think these signal are ussed for the LEDs KANA and CODE.

M60002A-0108FP:
Pin 33 is the signal for the slot 3-2.

The switch is probably to disable it to remove firmware.

I am interested in the Reset button. Is there anything else to add that push button?

Thank you for your response, yes the LED's seems to be related to those buttons somehow but something seems to be wrong becaus its stuck in special characters mode, i cant write any normal text, caps button seems to do nothing and while the any idea why that might be? Im thinking i might try to remove the LEDs and see if i can get back functionality but then id have two LED on the case that does nothing =/

is the added 74LS176 part of the disable switch? one cable goes to the rom chip pin..

As for the reset switch, its connected straight to those 2 pins, no additional circuitry or components.

By gdx

Prophet (2858)

gdx's picture

22-07-2019, 14:18

The 74LS176 seems used for LEDs and the firmware.

I think either the S1985 is damaged or it is the small added circuit but it can also be the keyboard. I guess you checked all the welds.

The S1985 is still sold:
https://articulo.mercadolibre.com.ar/MLA-715698815-talent-ms...

By RetroFletch

Supporter (13)

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22-07-2019, 14:37

I will try to go over it more carefully and measure things the info you gave me has been helpful to narrow things down a bit!