Re: Battlezone Half Screen, please help if you can

Yes the halo means the tube is being overdriven.

Can't say how often the caps fail, I would agree that they are durable.
Check that they are not shorted or shorted to the pcb ground-plane.

It is easy to see if these work. Just take a voltmeter/scope to the
voltage output on the follower op-amps. If you tell me which part of teh
BZ screen is missing, there will be a direct correlation to specific
devices in this section.

+Tim+

PS: Perhaps I should fix atari stuff in my spare time for a small fee, its
great once you get into it...Any takers in the UK?

MKDUD@aol.com
01/03/03 00:45

 
        To: ygroups@andora.org.uk
        cc:
        Subject: Re: VECTOR: Battlezone Half Screen, please help if you can

Hello Tim,

Normally, for BZ it says, set the +Y to say
about 60/70% of the vector range (for a +/- 10 volt range this means set
to about +6 volts), set clipping on the -Y to -10v, +X to +10 V and -X to
-10 v.

Ahh, this explains the "halo" effect I was seeing "BattleZone" was drawn
in demo mode with /ZBLANK forced high. The logo seemed to "halo" out
beyond the left and right side of the screen - so much for the idea of
leaving /ZBLANK forced high, even though I wouldn't have done that...I can
imagine the strain on the deflection transistors...

>>What you need to do is to check out the section for your half screen,
you
might need to be a little creative. 1. you don't need the diodes, they are

there for protection, you could lift them out, 2. you can check the
switch logic drive, ie, /HST /LST signals, they will only be low for a
very short time at the start of the vector cycle, 3. check the voltages on

the voltage follower outputs (C11) will, they will be as described above
when the game is running, or +/-10 volts in selft-test mode. You won;t be
able to check the caps, as you will probably discharge them. Finally, if
still no progress check every passive component around the amplifiers and
look for board shorts/baseplane shorts. <<

OK, I'm going to start checking this stuff now. Just a quick question,
though; how frequently do the caps C93 - C94 and C69 - C70 fail? I thought
these things were very durable??

Thanks Again for all the help,

Michael Kelley

---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to vectorlist-owner@synthcom.com.
Received on Sat Mar 1 00:03:23 2003