Commodore 1084S monitor
A. W. Jackson
my old videogame consoles (SNES, Saturn, etc.). I've tried the
monitor out and it is fully functional, but there's a slight flaw in
the picture. There are fuzzy vertical bars of slightly lighter/darker
brightness (most clearly visible against a black picture) near the
left edge of the screen, running the entire length of the screen from
top to bottom. The bars' position and size change when I adjust the
horizontal position and horizontal size knobs, so they're apparently
not actual phosphor burn-in (which leads me to hope that I might be
able to repair the problem). What kind of defect/damage might be
responsible for these bars, and is it repairable? I checked the
sci.electronics.repair TV repair and monitor repair FAQs and didn't
see anything that looked closely similar to my problem.
Also, I've been searching the web for information on this monitor, but
it seems that at different times (or in different territories)
Commodore sold several different monitors labelled "1084S", because
all the "1084S" documentation I've found on the web so far seems to be
for completely different monitors from mine. The monitor I have is a
"1084S-P" manafactured by Phillips in June 1988, according to the
label on the back. It has, for inputs, four RCA jacks (CVBS/L, C,
L.Audio and R.Audio), an 8-pin DIN for TTL RGB, and a 6-pin DIN for
analog RGB. There is also a plastic cover on the back which looks to
be the right shape and size for an SCART connector (possibly because
Commodore used the same case for both North American and European
versions of this monitor?) Also on the back are knobs for horizontal
position, horizontal size, vertical position, vertical size, a
pushbutton for switching between CVBS and LCA, and a pushbutton
labeled "VCR" whose function is unclear to me (nothing seems to change
on the screen when I push it). The front panel has knobs for hue,
brightness, contrast, color, sharpness, and volume, and a pushbutton
for switching between CVBS and RGB. Does anyone know where I can
download detailed information (such as a user's manual, or by some
miracle a schematic) for a "1084" matching this particular
description?
--Alex W. Jackson--
Overdoc
A. W. Jackson schrieb in Nachricht
<6fef4eae.03031...@posting.google.com>...
.......
> Does anyone know where I can
>download detailed information (such as a user's manual, or by some
>miracle a schematic) for a "1084" matching this particular
>description?
I think I have schematics for the 1084S-P. Just gotta find them... ;)
But I think your problem isn't related to the board, but to the tube
instead. You might have to adjust something there, but I have no idea what
and where.
Anyway, when I find the schematics I send them to you. :)
Reini
kev
Jackson) wrote:
hi there
got the schematic for the 1084S-P here
could be some modulation on the supply to the RGB drive stages
have a look at any electrolytic caps on the tube base
C717 4.7uF not sure about its voltage, maybe 250V as its on a 125V
rail.
or on the main board C144 and C 494 both 47uF 250V
If you want any scans from the manual just ask
kev
A. W. Jackson
> hi there
> got the schematic for the 1084S-P here
>
> could be some modulation on the supply to the RGB drive stages
>
> have a look at any electrolytic caps on the tube base
> C717 4.7uF not sure about its voltage, maybe 250V as its on a 125V
> rail.
> or on the main board C144 and C 494 both 47uF 250V
>
> If you want any scans from the manual just ask
> kev
Thanks for the repair advice.
I guess all I really want to know from the manual is, what's the
purpose of the mysterious "VCR" pushbutton on the back next to the
horizontal/vertical adjustment knobs?
--Alex W. Jackson--
Vector Viper
"A. W. Jackson" <awj_in...@hotmail.com> wrote in message news:6fef4eae.03031...@posting.google.com...
> I recently purchased a second-hand Commodore 1084S monitor to use with
> my old videogame consoles (SNES, Saturn, etc.).
> download detailed information (such as a user's manual, or by some
> miracle a schematic) for a "1084" matching this particular
> description?
Be VERY careful to get the right schematic! These monitors were farmed out to MANY
companies... I waited months many years ago for one, and it was useless...
Vector Viper
>
> --Alex W. Jackson--
Franc Zabkar
>I recently purchased a second-hand Commodore 1084S monitor ...
You'll find schematics for a 1084S here:
http://www.devili.iki.fi/Computers/Commodore/
Not sure if it's the same model though ...
-- Franc Zabkar
Please remove one 's' from my address when replying by email.
kev
Jackson) wrote:
all that switch does is apply 12v to the base of TS439 via R439 which
drags pin 13 of IC402 to 0.5V
IC402 is the horizontal signal processing IC, so its probably timebase
correction for VCR use
A. W. Jackson
> all that switch does is apply 12v to the base of TS439 via R439 which
> drags pin 13 of IC402 to 0.5V
> IC402 is the horizontal signal processing IC, so its probably timebase
> correction for VCR use
Ahh, that makes perfect sense. I guess the reason I didn't notice any
effect from the button is that the video source I was using was my
Playstation, which doesn't require timebase correction. Come to think
of it, even VCRs nowadays generally do it internally, don't they?
--Alex W. Jackson--
Overdoc
Vector Viper schrieb in Nachricht ...
>Be VERY careful to get the right schematic! These monitors were farmed out
to MANY
>companies... I waited months many years ago for one, and it was useless...
Which model of 1084 is your's ?
I think I have some different 1084 and 1084S schematics for both Philips and
Daewoo models.
Reini
Luddite
: I recently purchased a second-hand Commodore 1084S monitor to use with
: my old videogame consoles (SNES, Saturn, etc.). I've tried the
: monitor out and it is fully functional, but there's a slight flaw in
: the picture. There are fuzzy vertical bars of slightly lighter/darker
: brightness (most clearly visible against a black picture) near the
: left edge of the screen, running the entire length of the screen from
: top to bottom. The bars' position and size change when I adjust the
: horizontal position and horizontal size knobs, so they're apparently
These sound like jail bars caused by 60hz leaking into the video input
through a bad input cable,or on the board somewhere.
wiring too close to the rear of the picture tube can do this as well.
A. W. Jackson
I've never heard that term before (I'm not experienced at TV/monitor
repair, as you can probably tell) but "jail bars" is a pretty good
description of what the effect /looks/ like. How might I go about
finding the exact component that's at fault?
--Alex W. Jackson--
George Alibinisis
Google Groups Idiots Strike Again
to get you anything more than insults?
Idiot.
Rayner Lucas
george.a...@gmail.com says...
> On Monday, March 17, 2003 at 12:16:39 AM UTC+2, A. W. Jackson wrote:
> > I recently purchased a second-hand Commodore 1084S monitor to use with
> > my old videogame consoles (SNES, Saturn, etc.). I've tried the
> > monitor out and it is fully functional, but there's a slight flaw in
> > the picture. There are fuzzy vertical bars of slightly lighter/darker
> > brightness (most clearly visible against a black picture) near the
> > left edge of the screen, running the entire length of the screen from
> > top to bottom. The bars' position and size change when I adjust the
> > horizontal position and horizontal size knobs, so they're apparently
> > not actual phosphor burn-in (which leads me to hope that I might be
> > able to repair the problem). What kind of defect/damage might be
> > responsible for these bars, and is it repairable?
>
> exactly the same monitor. Thank you in advance!
unlikely that anyone remembers the result even if it did get fixed.
What have you tried so far to fix or narrow down the problem, if
anything?
It sounds like some kind of ghosting or ringing; is there a picture you
could upload anywhere (Imgur or similar) so we can see what it looks
like?
I'd start by swapping the video cable and also trying a different video
source, just to make sure it really is the monitor at fault. Then I'd
replace all electrolytic capacitors on general principle. These monitors
are decades old and there are probably multiple caps that have gone out
of spec by now, so just doing the whole lot can save multiple rounds of
troubleshooting.
There's a service manual for this monitor available at
http://www.zimmers.net/anonftp/pub/cbm/schematics/monitors/. The scan
quality is poor, but it's certainly better than nothing.
Rayner
--
Big-8 Management Board: https://www.big-8.org
Homepage: http://magic-cookie.co.uk
George Alibinisis
Firstly just wanna say to the Google Groups Einstein that the 18 year period doesn't matter as long as the problem was solved and the guy is still around on this earth. The Commode/Amiga retro-scene is very much alive.
Now I have posted lots of pics and info in this thread. I have already recapped the monitor and done a lot of measurements.
https://www.edaboard.com/threads/commodore-1084s-monitor-with-faint-vertical-lines.396322/
I thought I'd also ask here as Alex faced the exact same problem.
Thanks for your time Rayner.
Peter W.
George Alibinisis
> You do need to know that the position of Village Idiot is occupied by an Australian at this time. Much as you might wish to compete, your status will remain "incurably stupid", only. You may re-apply should the incumbent leave.
Peter W.
Then you are in full competition with Phil for the position? He may be relieved to know that.
George Alibinisis
Rayner Lucas
george.a...@gmail.com says...
> Firstly just wanna say to the Google Groups Einstein that the 18 year
> period doesn't matter as long as the problem was solved and the guy is
> still around on this earth. The Commode/Amiga retro-scene is very much
> alive.
>
> Now I have posted lots of pics and info in this thread. I have already
> recapped the monitor and done a lot of measurements.
>
> https://www.edaboard.com/threads/commodore-1084s-monitor-with-faint-
vertical-lines.396322/
>
> I thought I'd also ask here as Alex faced the exact same problem.
relevant post even if the original participants are no longer reading,
so in this case I don't think it's anything to get worked up about.
I see from that edaboard thread that you've already tried the most
likely solutions :-(
The slowly drifting *horizontal* lines you mention sound like hum bars,
i.e. excessive voltage ripple from the power supply making its way onto
the display. If this is the case you'd see two bars on screen at once
(100Hz ripple from a full-wave rectifier, on a screen with 50Hz vertical
refresh) Again, by far the most common cause is a bad filter capacitor
in the low-voltage power supply, but there can be other components at
fault. See https://www.repairfaq.org/sam/monfaq.htm#monrwphb
If you have access to an oscilloscope, you might want to check the
outputs of the power supply for unusually high ripple. In particular,
the output of the 12V DC regulator (IC403) ought to look nice and
stable, as the regulator should smooth out whatever makes it past the
filter capacitor.
Obligatory safety note: be very careful and don't work alone, these
things have some nasty voltages inside them (including that 125V DC
power supply output). I highly recommend the safety guidelines at
https://www.repairfaq.org/sam/monfaq.htm#montrbs
George Alibinisis
I read around the internet and there was this thread and just one more guy with same monitor, same issue. He told me on eab boards via private message that his monitor is with an expert at the moment.
it definetely looks like some harmonic but my knowledge in CRTs is very little at the moment - learning every day.
Rayner Lucas
george.a...@gmail.com says...
> thanks for all your efforts Rayner. I am using a 1:1 isolation
> transformer when I power up the monitor and I do have an oscope. Ill
> test the PSU although the lines are many more than two.. maybe 7-8
> drifting to the bottom of the screen. Thing is that there are brand
> new caps everywhere.
>
> I read around the internet and there was this thread and just one more
> guy with same monitor, same issue. He told me on eab boards via
> private message that his monitor is with an expert at the moment.
>
> it definetely looks like some harmonic but my knowledge in CRTs is
> very little at the moment - learning every day.
still worth checking the PSU output voltages for stability, though - it
will help to know whether you can rule that section out or not.
The number of horizontal lines suggests the unwanted oscillation has a
350 - 400Hz component, which might be a helpful clue.
If investigating the PSU doesn't reveal anything, here's how I'd look at
it. You've got a scope and a schematic annotated with expected voltages
and waveforms. The problem shows up on the display, therefore it must be
present among the signals and voltages that go to the CRT and deflection
yoke. If you can figure out which one(s), you can then trace it back to
the origin from there.
It seems highly unlikely to be anything to do with the EHT or the focus
grid voltage, which is good because those are the ones I'd least like to
be messing with.
It doesn't look much like a deflection problem either, as from the
pictures on the edaboard thread I can't see any actual distortion to the
image on screen.
As far as I can see, that mostly just leaves the:
+12V line
+125V line
-20V line
RGB signal lines
going to the CRT neck board as the likely candidates.
The safety guidelines at
https://www.repairfaq.org/sam/monfaq.htm#montrbs include some advice for
staying safe when investigating a running monitor; I particularly
recommend the bit about only ever connecting/disconnecting test leads
when the monitor is unpowered and unplugged.
Let us know if you manage to narrow it down.