Monday, October 11, 2010

[Amiga] Scandy A1200 Flicker Fixer

Hi people,



I've posted this article at amiga.org before, but as I want to keep track of all my projects here, I think it's okay to repeat.
Full view




The main PCB installed

Some time ago I got hold of a Scandy A1200 scan doubler module for the Amiga 1200. It consists of three PCBs which are plugged on top of LISA and both CIA chips inside the A1200. It features an additional VGA port, output is the same as on the video port, so you can use two monitors at the same time.
After some hours in vain trying to find a documentation about how to install it, I have decided to try on my own and let you folks know. I'd either find a way how to destroy the A1200, or successfully get the Scandy working. Luckily, the latter happened ;o)

In fact, cable lengths and positioning make it hard to mount the Scandy in more than one (correct) way, nevertheless I had felt better if there had been a paper instructing me.

After mounting it looks something like this:



Micronik has tried to indicate the orientation of the PCBs by putting the 45-degree edge of the socket in the same place it is on the respective chip, at least for LISA and the U7 CIA. The edge of the U8 does not point to the right direction though but never mind, as the pin count is the same on all edges it fits anyway.

The CIA sockets indicate where they belong so you can't do it wrong (see print beneath each socket):



U7 CIA (below parallel port)

U8 CIA (right above floppy connector)
Closeup of U7 and U8
All add-on PCBs


After some plugging and unplugging it finally worked. Maybe one should first check the socket pins for corrosion and dust which I forgot. My first results were "no VGA signal", and later the signal was first okay but seemed to collapse within a few seconds, with the CRT finally going to standby mode. No idea where that came from, eventually it seems to be okay.
Now I'll have to think about how to move the hard disk drive to another location as the Scandy becomes pretty warm over time. So please be warned: you should *not* put anything directly on top of the Scandy main PCB, it definitely needs some room to get rid of that heat!

The following photos were taken from a Dell WFP2407 TFT.


SysInfo

IntuiTest (640x512 @ 256 colours)

The IntuiTest screenshot indicates that there is no "flicker fixer" function. Scandy does not buffer complete frames but, to put it simple, buffers only the line that is currently sent to the CRT or TFT, and sends each pixel twice (i.e. with double speed) to the screen attached to the VGA port which in effect doubles the horizontal frequency without presenting a different content. I didn't expect anything else because a real flicker fixer is usually way more complex. This also explains why a Scandy A1200 only costs about half as much as, say, an Indivision 1200.
If you plan to use your A1200 mainly for gaming and less frequently for working (especially in interlace modes), the Scandy A1200 is a clever solution.
Just consider that most of the CompactFlash adapters will collide with the Scandy main PCB, as does my hard disk right now (missing the original metal shielding *argh*)

I hope this is helpful for some of you ;-)

Greets,
Joe

3 comments:

  1. Thanks to your images and description, I could connect my Scandy properly ;o)

    ReplyDelete
  2. I have the same unit installed in my A1200. However, I have noticed some graphic glitches on certain games. What about you?

    ReplyDelete
    Replies
    1. Hi ydeath30, well, I didn't use the A1200 for gaming a log. Most of my preferred games do not even use the AGA chipset but most are 320x256 in 32 colours, so they don't give the flicker fixer a real challenge. Actually I sold the Scandy some years ago and bought an Indivision external one that can be used on virtually any Amiga. Sorry I cannot help here.

      Delete

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