RE: Major Havoc Screen problems

 OK, Folks! Firstly, I know it has been awhile since I received the advice,
but I had to wait for chips 'n' parts before I could proceed with my
debugging/fixing.
 
1) I found the culprit of what I outlined below. It was in fact that pesky
DAC08CN (Digital-to-analog convertor). The bugger was on the fritz and was
causing all my scaling to blow up (ie. I could not use the pots to shrink
the screen nearly enough to bring it back to displayh fully in the monitor)
AND it was causing jumping. THis jumping was when the screen was changing
ie (lander is landing and the ship expands - the screen zooms in on the
ship) it was jumping to each frame as if it was missing frames instead of
being nice and smooth. And when you are in the screen to shoot the aliens a
'la isometric Galaga, those ships would jump around missing frames.
 
Of course, after a little schematic reading, turns out that the above DAC is
responsible for handling the linear scaling. Duh! I pulled that baby out,
slipped in a cool little socket, shoved another one of the above DACs in and
PRESTO! Game a working like there is no tomorrow. Fantastic
 
 
2) The other board that I looked at that had no video but was essentially
"playing blind" was due to those pesky little LF13201s. Darn little
buggers... I removed those guys as well, slipped in some sockets and pugged
in my recently purchased DG201ACJs and presto another one solved. Damn,
that's sweet.
 
3) I am still in the process of debugging a 3rd board that has no video. I
replaced all the items mentioned above (including the 6012s as well, but
still no go on the video...) A bit puzzled about this one. This one also
"plays blind". Gotta keep looking I guess.
 
As I said before, thanks to all for your help. If anyone has any
suggestions on number 3, let me know.
 
Cheers
Andy

-----Original Message-----
From: Rodger Boots [mailto:rlboots@cedar-rapids.net]
Sent: September 8, 2000 17:47
To: vectorlist@synthcom.com
Subject: Re: VECTOR: Major Havoc Screen problems

Looking at the schematics I have this suggestion:

Run selftest and see if the "shrinking box" still works. If it doesn't, Q7
might be stuck on or shorted (or Q6 turning Q7 on). This would take sizing
to maximum and totally kill the analog sizing functions.
  

"Evrovski, Andrew" wrote:

Hello Folks,

        I was going through the test modes adjusting MH pots to the screen
patterns as outline in the MH docs. There were screens with colour patterns
and cross-hatches etc and I followed the instructions for making
adjustments.

        At one point there is a screen with a red box around the screen and
then a white box just within and then another box (looked green although
manual said it should be white) that starts outside and shrinks smoothly in
the middle, till it disappears and then starts again. Anyhow I saw all
that, made adjustments and started to play the game. While I was playing
(about 15mins), all of a sudden the picture expanded on the screen such that
objects were way off the screen that I would normally see (almost like I
zoomed in on a part of the game - or as if I had adjusted the x & y size
pots. Anyhow, it was like this and I rebooted back to test mode to
re-adjust and could not shrink the screen back to the correct size (it was
still way to stretched). I also lost the red border around the tests
screens as well and the nice smooth shrinking box no longer is smooth.. it
skips sizes and just disappears and appears as a smaller box like it is in
jerky movement mode.

        Anyhow, I am assuming that my pot(s) blew or something is fishy with
them. These are the ones I was adjusting:

XBIP: R80 Pot - 200?
YBIP: R81 Pot - 200?

XSIZE: R34 Pot - 10K
YSIZE: R48 Pot - 10K

XCENT: R39 Pot - 10K
YCENT: R55 Pot - 10K

XLIN: R38 Pot - 2K
YLIN: R50 Pot - 2K

        Anyway, can anyone confirm that I need new pots (perhaps the
x-size/y-size ones) or does anyone know if it could be something else. Any
help is appreciated.

Thanks
/\A\n\d\y/

Andrew Evrovski
Development Director
Cyberplex Atlantic, Halifax, NS
(TSE:CX)

-- 
Windows: 
32 bit graphical interface for a 
16 bit patch for an 
8 bit operating system written for a 
4 bit processor by a 
2 bit company that can't stand 
1 bit of competition. 
  
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