A2000 psu and keyboard

[odious]

I picked up an Amiga2000 with its 1081 monitor. Well, the thing wont boot and from the psu a "tick" (it really sounds like a little spark) sound can be heard at frequency of 2 hz. Also, the speakers of the monitor output that same "tick" but at a lower tone at the same frequency.

The power led doesnt work and i have no +12V nor +5V at the molex conectors. So looking at the schematic of the a2000 there's +5V, GND +12V, -5V, -12V, KEY, S_user and TICK.

What are KEY, S_user and tick for? I am asking this because i thought of using an old pc psu to feed the miggy. Has anyone tried this?

Btw, this might be a stupid question, but can i use a pc kb, i mean, those with large dins?

Ebay is off the question, i have had some bad experiences with it.

Regards.

[orange]

I had exact same "tick" problem with A2000 PSU, so I replaced it with ATX.

The infamous TICK signal doesn't exist on PC PSUs. You can make one
or put jumper:

J300   This jumper determines the time base used for the 50/60Hz CIA
   timer chip.  In the normal position, the 50/60Hz TICK clock,
X-X X   based on AC line frequency, is used as a time base.  In the
   alternate position, the vertical sync pulse from the video
   section is used.  The system will not operate properly
   without one of these clocks.

warning: I'm not sure if its J300, there is some false info about that on net.

The S_user, IIRC is just +5V for mouse, but I'm not sure so check it.
dont know about KEY, maybe "empty pin" to make sure you don't put power connector wrong way.


no you cannot use PC keyboard without adapter, look at the one on site I mentioned.

PS. I used 300 W Chieftec, works like charm.
Only had to drill a hole in it to fasten to Amiga case.

[odious]

Thanks a lot, Orange,

I have been looking at the mainboard for that j300 for 20 minutes and didnt find it. Where is it located?

About the keyboard, i have to load a library before using the kb adaptor or its just plug and type?

I didnt pay attention to the key pin, lol, didnt see that it wasnt connected

Cheers

[JimS]

Before you hack a peecee power supply, check the fan in the Amiga supply. If it's dead or just stalled, the supply will shut off. You can disconnect it and try it on another power supply or even a car battery.

-Jim

[orange]

its somewhere below power supply, near right CIA chip, in top right corner looking at front of A2000, just above Paula.
No need for any software to run ATkeyboard adapter. You got Protel ready schematics on my site that 100% works, and aminet link to adapter. It works very nice.
You might have some slight problems in some games. Somehow it seemed to me there is slight delay (but it could be just me
 :roll: )

If you don't make Tick yourself, you can't use some Genlocks and clock might be slightly less accurate, but otherwise it will work great.

[orange]

Dont forget, you need to be checking (switching)power supply ALWAYS with some LOAD, otherwise its likely to not start at all or sometimes even break. ( I use 12V car lights)

I have been trying to find someone to repair Amiga PSU for years with no success. Everyone suggests its much safer to replace it, because when it fails usually several components inside PSU die.


 :-(


PS. I have seen very cheap A2000 PSUs on ebay but problem might be expensive postage..

and don't forget that PSU capacitors have dangoerous voltages even after being disconnected for long time

[odious]

Hi,

JimS: The fan although a bit noisy is running fine. It extracts quite a lot of air.

I tried to locate the j300 on my motherboard but again with no luck. Meanwhile i saw some pictures of 2000 mobos and they are different from mine.

I took some photos of the mobo and the revision:

http://img88.imageshack.us/img88/9617/mbdi1.jpg

http://img89.imageshack.us/img89/9999/revhz4.jpg

Can you point out the jumper?

Is it some early version? I've seen mobos with less and different components.

Regards and thanks for the help.

[JimS]

@Odious

It looks to me like you have one of the original German Amiga 2000s. To quote from the Source. :-)

MotherBoard Revisions according to Dave Haynie:

A2000-A german, like an A1000 in a different box, 512k CHIP, non-standard processor and video slots

Yes. The orginal A2000 was designed in Germany. It was based on an integration of the A1000 motherboard design and the example Zorro II backplane from "Schematics and Expansion Specifications", the A1000 hardware manual. It used the thin Agnus, which handled only 512K of DRAM. They added a "Genlock" slot, which was essentially just the 23-bit video signals on an internal connector, and the "MMU" slot, which was essentially just the A1000 external edge connector on an internal slot. The machine shipped with 512K of Fast RAM in this slot, though the case was slow and had some reliability problems. About 60,000 of these machines were made, so I've heard.

[odious]

Hi,

I searched with no luck for the manual for this revision. I must have spent an hour looking for the j300 or j201 since changing them would be more pratical because im not going to use genlocks, etc.

I have found some jumpers at the board but i have no documentation at all about them, so if anyone knows anything about jumper settings on this revision, it would be appreciated.

Regards