RBG monitor for Spectrum?
I'm using a very old TTL RGB monitor with my Spectrum, with a RGB adapter that I made many years for my Sinclair QL. It works perfectly with my QL, but it's very hard to get the vertical scrolling to stop with the Spectrum, and it when I do get it stopped, it doesn't stay steady long before it starts rolling again.
I built the adapter from a simple schematic that came qith the QL. I can't find the schematic at the moment, but there isn't much to it. Theres one chip and a capacitor, and the output is a 9 pin D-sub connector.
What monitors will work with the Spectrum? I purchased a couple adapter cables with a DIN connector at the Spectrum end and a SCART connector at the other end, but I've never even seen a monitor or TV with a SCART connector on it.
I've seen people mention using a 1084S monitor with the Spectrum. Is that an Amiga 1084 monitor? (I have one of those)
I built the adapter from a simple schematic that came qith the QL. I can't find the schematic at the moment, but there isn't much to it. Theres one chip and a capacitor, and the output is a 9 pin D-sub connector.
What monitors will work with the Spectrum? I purchased a couple adapter cables with a DIN connector at the Spectrum end and a SCART connector at the other end, but I've never even seen a monitor or TV with a SCART connector on it.
I've seen people mention using a 1084S monitor with the Spectrum. Is that an Amiga 1084 monitor? (I have one of those)
Post edited by KatManDEW on
Comments
http://womblesretrorepairshack.blogspot.com/2008/11/zx-spectrum-composite-video-mod.html
If it's a 128/+2 you can build a SCART cable which plugs into the monitor out jack, giving you real RGB Video
http://mts.speccy.cz/doc/128_rgb.pdf
I also found this link.
http://user.tninet.se/~vjz762w/rebuild.html
It describes several mods. First the composite video mod which is also mentioned by Shockwav3 but also a S-Video mod for the spectrum.
I tried out the S-Video mod with my 42 flat tv. The picture was really good. Also I used my 1084 (used cinch connectors luminance and chrominance), but the picture looks like a bit to bright. Looks like, the signal is to high or is handled different from the 1084 against a "normal" flat tv, I guess. Maybe our expert have an idea if they have a look on this mod. Thanks.
Composite video is not better than RGB. Besides, I think he's using a +2/+2A machine, as the original Spectrum cannot output RGB and it's not trivial to generate a RGB signal from the /Y U V signals from the ULA.
If you get a rolling picture, that would be because a poor vertical sync signal.
The adapter you're using, does it have a LM1881 sync separator? Or your monitor can accept composite sync?
If you have a 1084 monitor, that's your best choice.
- If you have a +2A/+3 machine, use a simple adapter from DIN to DB9/SCART (this one depends upon your 1084 model)
- If you have a +2 grey, make sure all PERITEL links are present, and remove any STANDARD link (inside the Spectrum PCB). Then, use the same adapter as above.
- If you have a 128K "toastrack" (or a +2 grey and you don't want to modify the internal jumpers), then make an adapter that can mix the "bright" signal with primary colors, and acommodates the voltages to feed an analog monitor. See details at http://www.fruitcake.plus.com/Sinclair/Spectrum128/SCARTCable/Spectrum128SCARTCable.htm
- If you have a 48K based machine, then you'll have to live with composite video, as there's not a cheap and easy solution to output RGB from it.
What is the 1084 monitor that everyone mentions? Is it an Amiga 1084 monitor? It has a 9 pin D-sub connector on it...
Here's a pic of my hastily assembled QL monitor adapter. It's just a hex inverter with a decoupling capacitor on the power for the chip. It's inverting one of the video signals. It works perfectly with my QL, and the video is rock solid, with no vertical scrolling.
It was not difficult to build the cable, but the monitor interpreted the black colour with bright signal enabled as GRAY (!), so logic should be incorporated to cancel bright signal for black color.
That is: LK2, LK3 and LK8 should be present, and LK4, LK1 and LK7 should be removed.
If you won't use your Spectrum in any than the 1084 monitor, then you can remove LK2 and put LK4. This way, you'll have RGB and composite video at the same connector, but you will loose the 12V signal, needed for some TV's to auto switch to RGB mode when you plug a Spectrum-to-RGB SCART cable.
Also check that the components marked with # are present.
If you prefer to use the composite video signal, put LK4 and LK8, and remove LK2 and LK7. This will bring you video at DIN pin1, and sound at DIN pin 3. Common GND for video and audio at pin 2.
If you have a 1084 monitor with a DB9 connector at the back, you surely have a 1084S monitor. The DB9 connector accepts analog RGB signals. This is the pinout:
1 = Sync ground
2 = RGB ground
3 = Red
4 = Green
5 = Blue
7 = Composite Sync
6,8 and 9 = no connection
What video signal is the circuit inverting? For the Spectrum, the composite sync signal is already at the right polarization, so no need to invert it. Besides, if you invert it, then you will face the kind of sync problems you're having.
I don't know which signal it's inverting. I can't find the QL schematic that I used to make the adapter. I found it last winter, but I couldn't find my adapter. I did some major cleaning and organizing this summer, and I found the adapter, but now I can't find the schematic! :evil:
I just now tried it without the inverter, but the horizontal is torn up beyond recognition without the inverter, and it still has the unstable vertical rolling.
I appreciate all the info everyone has posted. Some very good stuff there.
I have the RGB/Scart cables for my Spectrums (+2 and +3), and a female SCART/DB9 converter. Cables and adapters are built by a friend.
Also I have an RGB/Scart cable for my QL; I had it when I bought the QL some year ago, so I don't know how it's wired.
So, in order to connect to the 1084, I always need the RGB/Scart cable to be connected to the SCART/DB9 adapter.
the QL displays a good steady picture (85 column mode too).
the Spectrum cables work great on my TV, but displays a rolling picture on 1084.
So I think everything is wired correctly on cables and adapters.
What is missing for Spectrums? Can be the adapter be "adapted" (:-D) in order to work with Spectrums and continue to work on the QL?
You have to toggle Pins 4 and 5 of DIN plug that is plugged into +2 to use the QL cable for gray +2.
Connection table for comparing QL and gray +2
signal.......QL-Pin.....+2-Pin
C-Video.......3............1
BW-Video.....1..........n/c
ground.........2...........2
V-Sync........4...........5 (if LK1 is present and LK3 is absent)
C-Sync........5...........4
red..............6...........6
green...........7...........7
blue.............8...........8
audio..........n/c..........3 (if LK8 is present and LK7 is absent)
+12V..........n/c..........5 (if LK3 is present and LK1 is absent)
Bright.........n/c..........3 (if LK7 is present and LK8 is absent)
n/c ... not connected
LKx ... soldered jumper inside Spectrum +2
Note that you have to be sure to have the right LKx jumpers set inside +2 to meet the demands of your monitor.
Greets Ingo.
There is a RGB to Svideo board called 'A22'
http://www.arcademvs.com/accesseriors/A-22.jpg
I did not tried this with the speccy, but a friend of mine had a sort of
success with a C128D (the 80columns mode is RGB-TTL), he has some issues with the intensity.. but this thing works...
Chris
IIRC the 1084 and 1084s (s= stereo) have analog RGB input.
BUT I remember it was one model of monitor from Commodore that had
a '80 columns' switch to connect the C128 (the 80 columns were produced as
RGBI (TTL)). check if there is switch (on the back/front) on this monitor...
Not sure if your +2 has analog or TTL RGB....
I think the 128/+2 have TTL and the +2a/+3 analog RGB.. or .. ??
Chris
The video output format situation sure is a mess. I didn't want to make a major project out of connecting the used Speccy I purchased to a monitor.
Thanks again to all for all the information.
I just found on my ebooks collection the 1084s (stereo input) manual.
it supports BOTH analog and TTL RGBI, there is a switch on the back that
sets the analog/TTL RGB.
Pinouts of the Dsub connector:
(1) (2) (3) (4) (5)
(6) (7) (8) (9)
1 Ground
2 Ground
3 Red
4 Green
5 Blue
6 Intensity
7 n/c
8 HSync
9 VSync
IIRC the speccy has no intensity output, you can use/hack( put some components on) the brightness ...(!?)
chris
ingo.
Speccy <-> 1084
VSync = VSync
CSync = HSync ???
I have a 1084 with both RGB TTL/analog and would like to use it with a toastrack but was never quite sure how to connect the sync-signals :confused:
as I read on that site:
http://www.gamesx.com/hwb/co_ZxSpectrum128Rgb.html
your 128 has csync on pin 4...
you have to set the monitor to TTL signal mode..
I'm a happy camper now :smile:
A special circuitry with resistors and diodes can overcome this problem. Therefore it is much more simple to use the analog mode.
I also do this with my +2 with very good results.
Ingo.
The problem that annoyed me is the BROW color instead of dark YELLOW.
The interesting part is that the dark yellow is forced to brown IN THE MONITOR. Anyway, i removed a resistor in the monitor circuit and the dark yellow is back!
Just wanted to share the experience.
Interesting, I m curious what resistor was, do you remember?
Thanx in advance
Chris
Well, the monitor I have is actually an Amiga CM8833, not 1084, but every CGA monitor does replace dark yellow with brown, it was a convention of IBM.
I got the service manual from here: http://nightfall.xbox4fun.com/?p=2249 .
I *think* I disconnected the resistor R266 (section E7, page 7 schematics).
The circuit basically does this: if R and G are up and B and I down, then half the value of G.