A1000 rebuild / fault finding

mjnurney

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My original A1000 , my first one died one day about four years ago ...i don't know why but one day it never booted again. black screen.

i did the usual thing , changed all the socketed chips but no nothing..so it was packed away in the dead section for a year or three.

Well yesterday i got the lets fix it bug...

but no A1000 PSU , ill hot wire a pico PSU ...dont like that , ill hot wire an A2000 PSU as it has the tick signal...ok.

i changed all the socketed chips again from a working 500 , except Agnus. No joy here.

i then fitted a kickstart adaptor that i borrowed about 4 years ago ....must return it, that didn't work either but i did get a faint beep at power up.

now i had no boot up sequence of lights, no kickstart , zip...just a black screen but a quiet beep.

i tried other kickstart in the adaptor but either nothing or quiet beep.

So maybe its ROM related , the power light flickers too?

i removed the kickstart adapter and put it back as normal ...and nothing,its dead. So what if i try the ACA500 either though Jens says do not fit it. the pinouts are the same on a500/a1000 just incorrect orientation.

and bingo it lives! , I've hot wired an A500 keyboard on to the 1000 for the moment. Data, clock,gnd,+5v

video & audio all good.

So whats actually wrong? well the kickstart ROMs (79,80) are dead i think , I've ordered two more from Germany but its alive...first time in 4 years :)

MOS
252179-01
©1985 CBM
5185 TAIWAN
28005A-0054

MOS
252180-01
©1985 CBM
5085 TAIWAN
28005A-0055
now i can get back to sleeping properly , 2am bedtimes are no good!

2am video below


https://www.youtube.com/watch?v=au9TKd-zGpM


ultimately I'm going to rehouse this in a good A1000 case , clean up the keyboard and make a pretty A1000 and plonk an big heavy commodore CRT screen on it :)


A1000 pinout data.

Keyboard +5v, data,clock,ground (my 5v line is about 5.18v)

motherboard---| GND
PCB ............---| CLK
here............---| DATA
..................---| 5V

A1000 PSU connector (motherboard end)

1 * -5v
2 * +12v
3 * GND
4 * GND
5 * +5v
6 * +5v
7 * tick sync

A500 keyboard connector (wire end)

1 DATA
2 CLOCK
3 (not needed)
4 +5V
5 (no pin here)
6 GND
7 (not needed)
8 (not needed)

A2000 PSU pinout

YYYYBBBBO RGWU

U=Brown wire
gap = missing wire in connector

or
1 +5
2 +5
3 +5
4 +5
5 GND
6 GND
7 GND
8 GND
9 +12
10 no wire (keyway)
11 -12
12 +5 USR
13 -5
14 TICK
 

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BloodyCactus

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nice work! I dont think I've seen an pal A1k mobo, only ntsc with daughterboard. nice! :) kinda surprised that your masked boot roms are dead. if you have the right type, you can replace them. they are 256kbit eeproms. I cant think of the type offhand
 

mjnurney

we live as we dream. Alone.
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Yes it's a strange one

not sure I have the EPROMs or the odd & even bin files anyway
 

BloodyCactus

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I have the odd/even files if you need them, I read them from my NTSC miggy 1k, now I dont know if there were differences in the boot of pal vs ntsc or not, but I have them somewhere if you need them
 

cpiace64

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i need verify if i have original working proms for your mainboard and a psu, tomorrow update with more info
 

mjnurney

we live as we dream. Alone.
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Brilliant , great stuff

do you have a 1000 floppy?
 

cpiace64

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the floppy at the moment is on gba1000 in the house of my friend in Venice but i can send a pm for shipment to me for verify if work

the my psu need a new fan or you can use your and other test
 

mjnurney

we live as we dream. Alone.
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So a little more on the 1000.

I have been sent a set of used ROMS 79,80 but i still get no boot screen for some reason? just a black screen. Oh well.

but i do have a new PSU , yay posted very quickly and plugged in and fitted so I'm only short of a floppy drive at the moment then i can build it up finally.

So the black screen....

no boot sound and no white kickstart just a black screen and an occasional low pitched bleep but no jingle.

The only chipset chip i haven't changed is the Agnus 8367 as its DIP in the 1000.

mike.
 

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mjnurney

we live as we dream. Alone.
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no worries , as you see i got a new / old one in the end :)
 
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