Amiga 2000 Power Supply and TICK
Aki Honkasuo
changed Amiga 2000 power supply to PC AT power supply. There is a pin for
"TICK". What this "TICK" mean? Voltages pins are in right order. Old Amiga
2000 still does not work. When I put power on I see a "zap" on monitor
(composite video). I mean fast white "zap" and after that just black.
Amiga has "working" video signal but it is black screen. No booting on
floppy or harddisk :(
Any ideas?
Pin outs:
http://www.technonomicon.org/amiga/tech.info/pinout.power.html
http://www.technick.net/pinconmth_at_power.htm
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Martijn van Buul
> I got Amiga 2000 from my frend because the power supply was broken.
You may have more luck in one of the comp.sys.amiga.* newsgroups,
comp.sys.cbm is dedicated to 8-bit Commodore machines.
> I have changed Amiga 2000 power supply to PC AT power supply. There is a pin
> for "TICK". What this "TICK" mean?
Wild assumption: It's the 50 or 60 Hz clock line.
> Voltages pins are in right order. Old Amiga 2000 still does not work. When I
> put power on I see a "zap" on monitor (composite video). I mean fast white
> "zap" and after that just black. Amiga has "working" video signal but it is
> black screen. No booting on floppy or harddisk :(
I think your Amiga might have more problems. I don't know the Amiga by heart,
but I do know that a failing power supply might blow the Amiga; at least
a failing PS in an Amiga 500 does this :(
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Canadian CoCo Nut
for video timing. I believe that J200 changed from current settings to
the other will allow the Amiga 2000 to use the fake Tick from the PIA.
The other solution is to use (1) 100K ohm 1/2W resistor, (1) opto
coupler, (1) 7407, (3) 0.01uF 16V caps, (3) 3.3K ohm 1/4W resistors. If
you want I can redraw the schematics from memory and E-Mail them to
you. You need a real Tick signal to use any cards properly in the video
slot, like a frame grabber or a video genlocking device.
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Aki Honkasuo
> The Tick signal is a square wave of the wall cycles, this is required
> for video timing. I believe that J200 changed from current settings to
> the other will allow the Amiga 2000 to use the fake Tick from the PIA.
> The other solution is to use (1) 100K ohm 1/2W resistor, (1) opto
> coupler, (1) 7407, (3) 0.01uF 16V caps, (3) 3.3K ohm 1/4W resistors. If
> you want I can redraw the schematics from memory and E-Mail them to
> you. You need a real Tick signal to use any cards properly in the video
> slot, like a frame grabber or a video genlocking device.
Schematics for RC-oscilator will be nice O:-) I hope the motherboard is
not damaged by broken power supply. I can also trimp the RC-oscilator with
useing old scope.
Canadian CoCo Nut
pino+com...@dohd.org (Martijn van Buul) wrote:
> I think your Amiga might have more problems. I don't know the Amiga
by heart,
> but I do know that a failing power supply might blow the Amiga; at
least
> a failing PS in an Amiga 500 does this :(
In the A-500 PS that would destroy the A-500 computer the fault was
due to the crappy adjustable resistors used to set the +5V and +12V.
Any PS that had this setup I would immediately replace the PCB mounted
resistors with same value multi turn pots which were then glued to the
heatsink for easy adjustment when I was making a living repairing the
Amiga's I did this mod to about 75 units in 4 years. This only applies
to the linear PS the heavy ones with the mains power transformer. The
switching PS does not have this problem, but does not seem to be able
to handle the same load.