[ukvac] TECH : Battlezone troubles... continued..
hi all..
OK, if you're getting tired of hearing about my continued troubles then skip
this message now... otherwise, please read on
It gets a bit involved at
this point in the repair, so have the schematics sheet handy (battlezone
schematics sheet 2, side B)
OK, following the advice of Chad at the last meeting, i decided to replace
the 74s74 at location J10. This is because i traced the z blank signal as
far back as here, LOW at all times. Now, the 7474 is recieving inputs
correctly (DVY 8 at pin 12, and LATCH1 on pin 11), but it's output at pin 9
is still LOW. I don't know exactly what else it needs to output correctly at
pin 9, i don't really understand the logic involved in its entirety.. now, i
understand that it's a dual-type flip-flop, and the SET/RESET lines (coming
in from pin 10 and 13) obviously make the whole thing tick.. They are both
HIGH at all times..
My problem is, i've replaced the 7474 and i'm getting the same results,
there isn't (seemingly) a problem with the inputs on pins 11 and 12, but the
set/reset lines on pins 10 and 13 are a worry, they're high at all times,
should they be doing something else?
the schematics show them both as P,R67 does this mean they've just been tied
high from a resistor?
so anyhow, i'm back to square one, i hoped that the replacement of the 7474
would sort it out, alas, as we all know, hoping for a quick fix never works
I also had to go to Maplins and buy a new soldering iron as i was unable to
get heat right where i wanted when removing the chip, i picked up a baby
ANTEX soldering iron with a pinpoint tip for 15 quid, and blimey i'm
extremely impressed!
anyhow, any help is much appreciated!
seeya!
=============================================
Andy Welburn - Collector Of Fine Video Game Antiquities
http://www.willowsp.u-net.com/andy/
>>>> CURRENTLY MOST WANTED <<<<
WORKING Atari Asteroids Boardset
==============================================
------------------------------------------------------------------------
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hi all..
OK, if you're getting tired of hearing about my continued troubles then skip
this message now... otherwise, please read on
It gets a bit involved at this point in the repair, so have the schematics sheet handy
(battlezone schematics sheet 2, side B)
OK, following the advice of Chad at the last meeting, i decided to replace
the 74s74 at location J10. This is because i traced the z blank signal as
far back as here, LOW at all times. Now, the 7474 is recieving inputs
correctly (DVY 8 at pin 12, and LATCH1 on pin 11), but it's output at pin 9
is still LOW. I don't know exactly what else it needs to output correctly at
pin 9, i don't really understand the logic involved in its entirety.. now, i
understand that it's a dual-type flip-flop, and the SET/RESET lines (coming
in from pin 10 and 13) obviously make the whole thing tick.. They are both
HIGH at all times..
My problem is, i've replaced the 7474 and i'm getting the same results,
there isn't (seemingly) a problem with the inputs on pins 11 and 12, but the
set/reset lines on pins 10 and 13 are a worry, they're high at all times,
should they be doing something else?
the schematics show them both as P,R67 does this mean they've just been tied
high from a resistor?
so anyhow, i'm back to square one, i hoped that the replacement of the 7474
would sort it out, alas, as we all know, hoping for a quick fix never works
I also had to go to Maplins and buy a new soldering iron as i was unable to
get heat right where i wanted when removing the chip, i picked up a baby
ANTEX soldering iron with a pinpoint tip for 15 quid, and blimey i'm
extremely impressed!
anyhow, any help is much appreciated!
seeya!
=============================================
Andy Welburn - Collector Of Fine Video Game Antiquities
http://www.willowsp.u-net.com/andy/
>>>> CURRENTLY MOST WANTED <<<<
WORKING Atari Asteroids Boardset
==============================================
------------------------------------------------------------------------
Get what you deserve with NextCard Visa! ZERO! Rates as low as
0.0% Intro APR, online balance transfers, Rewards Points, no
hidden fees, and much more! Get NextCard today and get the credit
you deserve! Apply now! Get your NextCard Visa at:
http://click.egroups.com/1/970/5/_/5935/_/951844926/
-- Create a poll/survey for your group!
-- http://www.egroups.com/vote?listname=ukvac&m=1