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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: arttu80 on September 06, 2007, 09:10:58 PM

Title: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: arttu80 on September 06, 2007, 09:10:58 PM

Greetings from Finland!

I have problem with my A2000 power supply, it doesn't seem to work anymore. I know it is possible to change few little parts in it, but I wanted to try PC atx -type supply. I already installed and tried it, but my dear Amiga only flicks gray and white :-o  (with power led flickering at about 1/second rate)...

I know it must be that TICK signal, which isnt there in PC power supply..sooo, how can I bypass it? I know its quite easy on B2000 by changing jumper position, BUT on this rev 4 motherboard?!?

I will appreciate any replies!

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: hamtronix on September 06, 2007, 09:14:24 PM

http://www.amiga.org/forums/showthread.php?t=30810

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: arttu80 on September 07, 2007, 03:59:47 PM

Well, thanks for reply, but I specificly meant A2000 motherboard, there is no jumper to use internal clock?

So only option is to make TICK generator as per original PSU???

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: Andeda on September 07, 2007, 08:26:49 PM

You need to change jumper J300 to cover pins 2-3, so that the TICK signal is provided internally by the VSYNC signal.
And it works fine in my A2000  :-)

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: Andeda on September 07, 2007, 08:35:57 PM

sorry, i did not read from the beginning, so you dont have this internal opportunity. then you just have to build a external tick generator, there was a discussion about this some time ago.

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: rkauer on September 08, 2007, 02:31:41 AM

 You can use this hack:rtfm: (http://aminet.net/docs/hard/Mix_and_Tick.lha)

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: arttu80 on September 08, 2007, 11:55:34 AM

Thanks to all for replies.

rkauer:

I'll try out that hack! Thx.  :rtfm:

Title: Re: Amiga 2000 a-model power supply (to PC supply conversion)
Post by: Zac67 on September 08, 2007, 12:11:55 PM

Alternatively, you could just connect Agnus' _VSYNC output to the _TICK signal - that's what J300 does.
Using _VSYNC as _TICK raises problems when you change the vertical scan rate, but the OCS Agnus can't do that anyway.

You'd probably want to disconnect (=cut) the appropriate trace to the PSU to make sure _VSYNC and PSU _TICK are isolated.