Question about Jumper J36 on Amiga 2000 A motherboard

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Meinhard Ullrich

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Jun 5, 1991, 6:52:22 AM6/5/91
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I purchased a flicker fixer card (DeInterlace Card from MacroSystem, Germany)
last week and run into some troubles. The handbook reads that in case of such
troubles the user should plug in the jumper 300 in a different way. Well, I
looked not only at the motherboard but in my pockets, my cupboard and on many
more places, too, but I cannot find that damned jumper. The only jumper I found
is called J36 and has only two pins (J300 is said to have 3 pins, so you can
stick it in in two ways). The computer is an Amiga 2000 A (grr), board revision
4.

Can anybody tell me the meaning of the Jumper J36. Has it an analogous meaning
as the J300? What else can I do quickly. It is _very_ difficult to find the
line to MacroSystems not engaged.

Any help appreciated. Commodore, do you hear me?


Meinhard Ullrich
University of Erlangen, Germany

E-Mail: mdul...@faui09.informatik.uni-erlangen.de

Dave Haynie

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Jun 6, 1991, 3:54:17 PM6/6/91
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In article <mdullric.676119142@faui09> mdul...@faui09.informatik.uni-erlangen.de (Meinhard Ullrich) writes:
>I purchased a flicker fixer card (DeInterlace Card from MacroSystem, Germany)
>last week and run into some troubles. The handbook reads that in case of such
>troubles the user should plug in the jumper 300 in a different way.

J300 is the TICK jumper on the A2000b. It sets the timebase for one of the CIA
chips to either VSYNC or the 50/60Hz tick from the power supply. Normally, you
want the 50/60Hz line, as it's more accurate in most areas than the VSYNC
signal. Some A2000's were made with J300 set to VSYNC. Apparently, some of
these scan converters are sensitive to loading on VSYNC, and don't work well
if J300 is in the VSYNC position.

>Well, I looked not only at the motherboard but in my pockets, my cupboard
>and on many more places, too, but I cannot find that damned jumper.

If you have the German motherboard, there is no J300 equivalent. You're in
the 50/60Hz position permanently. J300 was my idea. Its main use is to let
you run an A2000 without the absolute need for an external 50/60Hz TICK.

>The only jumper I found is called J36 and has only two pins

As I recall, J36 is the "DF1: ID Enable" jumper, equivalent to J301 on the
"B" motherboard.


>The computer is an Amiga 2000 A (grr), board revision 4.

I assume this deinterlacer is some kind of hack that lives under the Denise
chip. I don't know anything about it in particular, but it's a certainty that
normal scan converter cards, like flickerFixer and the C= one, which live in
the video slot, won't work on the A2000a. The A2000a only has half a video
slot; it's enough to support a Genlock, but it doesn't bring out the full
digital video that's used by these scan converters.

>It is _very_ difficult to find the line to MacroSystems not engaged.

Sounds like you had better keep trying. It doesn't sound like there's anything
we can do from the C= end of things.
--
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
{uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy
"This is my mistake. Let me make it good." -R.E.M.

Peter Kittel GERMANY

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Jun 6, 1991, 4:40:05 AM6/6/91
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In article <mdullric.676119142@faui09> mdul...@faui09.informatik.uni-erlangen.de (Meinhard Ullrich) writes:
>I purchased a flicker fixer card (DeInterlace Card from MacroSystem, Germany)
>last week and run into some troubles. The handbook reads that in case of such
>troubles the user should plug in the jumper 300 in a different way. Well, I
>looked not only at the motherboard but in my pockets, my cupboard and on many
>more places, too, but I cannot find that damned jumper. The only jumper I found
>is called J36 and has only two pins (J300 is said to have 3 pins, so you can
>stick it in in two ways). The computer is an Amiga 2000 A (grr), board revision
>4.

On the A2000A board you change jumper J34 for the flicker fixer card.
It switches the Tick signal going into pin 19 of CIA on U10 between the
Tick from the power supply and the vertical sync signal VSY. It might
be that this is a solder jumper on your board.

The jumper J36 serves to tell the system you installed a second internal
floppy (then you must shorten it).

--
Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions...
Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk

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