#C1962/1952 Monitors
10 messages in this thread
Bruce:
PMFJI, but while I've got your attention…..
I've got the 'SyncStrainer', and it works just great! Have been using my
NEC3D in all modes, _AND_ running my Toaster when needed for almost a year
now.
Anyway, my question relates to the hardware hack that showed up here
recently to clear up vertical bars in the Amiga display. Appearantly, it
is a common problem to notice dim variations in the brightness of the
Amiga video out which appear as vertical bars (_very_ slight) on any
monitor. Alas, my machine suffers from this display problem.
The text file claims you can 'fix' the problem by adding a 100 Ohm
resistor to the 23-15 pin C= VGA Adaptor. The diagram shows the resistor
going between Pin 15 on the 23 pin connector to Ground.
My questions are:
1. Would this _really_ work?
2. Would this work on the Sync Strainer?
TIA for any help you can offer,
Erik Flom
Erik,
Yes in both cases. Pin 15 of the Amiga video port is a 3.58 MHz square wave
that is just waving in the breeze. Without any load, its full 5v signal is
cross-talking into its two closest neighbors, Red and Green. If only 1% of that
signal is coupled, you'll see it (remember, everyone complains about the lack
of saturated black on the Toaster).
This mod _will_ work on the Sync Strainer. However, the case we use is not
designed to be opened and closed repeatedly. It can be done but it's a
nuisance. If you'd like I can swap you a mod'd unit for your old one.
___
/__) ,_ _ _
_/__) / /__/ /_ /_-'
Interesting, I wonodered why it worked!
Bob Comer — AmigaDOS and OS/2, the only way to compute!
Cheyenne, Wyoming U.S.A.
Thanks much for the prompt reply! This is good news!
The exlpanation really helped. The message I DL'd didn't really explain
why or how the mod worked – that was enough to make me kind of leery of
the whole idea.
That's very generous of you to offer to swap out my unit with a modified
one! I may take you up on it (I did notice the 'one-time' assy techniques
used in your case), but I'd hate to go w/o my VGA monitor for a few days.
:^)
I'll take a look at it, and if it looks like too much of a pain, I'll send
it to you.
Thanks again for your help!
Erik Flom
>1. Would this _really_ work?
Yes, it does! It works great on my 23-15 pin adapter, but I don't know if
it'll help the sync-strainer.
Bob Comer — AmigaDOS and OS/2, the only way to compute!
Cheyenne, Wyoming U.S.A.
Thanks much! The message I DL'd was lacking in technical details, so I was
unsure if it was some evil prank, or for real.
Bruce, from PreVue Tech., assured me it would work on the SyncStrainer
too.
Thanks,
Erik Flom
Your welcome!
I was surprised how well it looked after I tried it!
Now for the big question, why didn't they build it into the adapter????
Bob Comer — AmigaDOS and OS/2, the only way to compute!
Cheyenne, Wyoming U.S.A.
"why didn't they build it into the adapter????"
So they could sell an extra 'hum-bucker' to you and make some extra dough,
of course!
Maybe it was an 'executive' decision by that PCjr weenie that was supposed
to be in charge at the time. (One less resistor….saves money ya' know.
:^)
Erik Flom
EF >>Anyway, my question relates to the hardware hack that showed up here
recently to clear up vertical bars in the Amiga display.<<
EF >>1. Would this _really_ work?<<
Yes it works. I followed the thread on USENET were this hack originated.
The vertical banding problem is caused by 'cross talk' between two of the
pins on the Video port. If the pins had be arranged differently, the
problem might not have developped, but it didn't become noticable until
VGA syncs were used.
I believe the resister acts as a either a filter (weakening the strenght
of signal being putout by the offending pin), or grounds the pin so it
doesn't generate a ~15-kHz signal.
—
EF >>2. Would this work on the Sync Strainer?<<
I don't know. I'm not sure, but I believe the Video pin causing the
banding was used for genlocking.
Ron.
– ap'ing with AP. (Eagles may fly, but weasels aren't sucked
into jet engines.)