1084S Monitor Problem

[tomcat666]

Hi!

I have a problem with my 1084S monitor. I want to connect all 4 of my old computers to it but so far only Amiga and C64 worked. The other two are ZX Spectrum +2 and Amstrad CPC 464. These two both have RGB outputs and when I connect them to the TV they both display a very good picture.
However if I connect them to the 1084S they both lack SYNC - the picture is "running". I tried everything but couldn't get a steady picture.
Both computers have similar outputs - RGB and SYNC output (which goes to pin 20 on SCART otherwise).
The 1084S is lacking the SCART connector, but has the usual RGB (TTL and analogue) and Y/C inputs.

Any help would be greatly appretiated !

[Amiga1992]

Where are you connecting the computer's sync? you should be conencting to composite sync.

[tomcat666]

Which one is the Composite SYNC ? There are two SYNC's on this page :

http://wired.hard.ru/data/pin_C1084d.shtml

the VSYNC and HSYNC - On my Amiga only one is connected, unfortunetly I don't have the cables here now to check this

Here are also the connectors for Amstrad and Spectrum :

http://wired.hard.ru/data/pin_ZxSpectrum128Rgb.shtml

From this page I gather the HSYNC is the Composite SYNC ???

Amstrad only has one SYNC in the pinout (and a signal called LUMA) :

http://wired.hard.ru/data/pin_Amstra...8Monitor.shtml

I wish I had the cables here ...

Tomaz

[Jope]

Originally Posted by tomcat666

Which one is the Composite SYNC ? There are two SYNC's on this page :

the VSYNC and HSYNC - On my Amiga only one is connected, unfortunetly I don't have the cables here now to check this :(

http://www.hut.fi/Misc/Electronics/f...rgb/scart.html

There is a circuit for making h+vsync out of a composite sync under the title "Composite sync to HSYNC and VSYNC converter"

By the way, the ones with scart seem to handle composite sync just fine. IIRC it's fed into the composite connector, but it's been a while since I last took a look.. Now I can't be bothered to dig up the schematics..

Hope you can get it to work.

EDIT: PS. the wiring diagram for the Amiga -> 1084 cable are here: http://hardwarebook.net/cable/av/ami...84monitor.html. They connect the csync to the monitor's hsync pin.. You might want to try that?

Seems that .ru site you use has stolen the pinouts and even the connector diagrams from the Hardware book.. :-D Oh well. Hope they have permission.

[tomcat666]

Thanx for the link !

I am sure this will be helpfull. I just remembered that I connected only one SYNC of the ZX/CPC output to the 1084. The problem is that CPC only has one SYNC. And since the Amiga only outputs CSYNC and is connected to HSYNC on the 1084 this SHOULD work with the ZX/CPC too, but it doesn't.

Somewhere I heard that ZX/CPC might have INVERTED SYNC outputs and they need inverting before they can be fed into 1084... any info on that ?
Here is the link (it is a simple invert circuit...) :

http://www.twobits.com/sync.html

I hope to have some time free in 2 weeks to test all this... unfotunetly the Amiga is at my parents house now (until I move)...

TC

[Amiga1992]

I am not SURE about this, we will have to wait for Overdoc to pop around, but I thik you can connect composite sync to the monitor's vsync and it would work fine. I remember being told this when I wanted to connect my Amstrad CPC6128 to my 1084.

[Jope]

Originally Posted by Akira

I am not SURE about this, we will have to wait for Overdoc to pop around, but I thik you can connect composite sync to the monitor's vsync and it would work fine. I remember being told this when I wanted to connect my Amstrad CPC6128 to my 1084.

But the Amiga's composite sync goes to horizontal sync on the monitor.. Why would the Amstrad's sync go to the vertical pin?

The best option here is still the sync splitter.. Guaranteed results. :-)

[Syko]

HSYNC is horizontal sync - ie per line; VSYNC is vertical sync - ie per frame

composite sync is both of these signals combined... if the monitor is fine with the CSYNC from the Amiga, then you should be able to connect H to H and V to V to get a stable picture (depending on inverted/non-iverted signal issue). Alternatively, you could convert the H/V into composite sync, and connect it like the miggy...

[gary]

I think when I connected an Amiga to an arcade monitor I connected bothe HSYNC and VSYNC to the monitors single SYNC input. Have you tried connecting the single sync output from one of the computers to both H+V sync inputs on the 1084?

[tomcat666]

Yes - I remember trying all possible combinations and none worked. Several people have said it might be that 1084 cannot handle inverted SYNC input, so next thing I will probably try building that. The only problem is the +5V for the inverter IC

[Syko]

see joystick port

[Overdoc]

Well, must be a problem with the inverted sync signals.
When you connect an Amiga to an old 1084 then you just connect composite sync from the Amiga to the h-sync input on the 1084, and everything is fine
But you are a little bit unlucky because later 1084 models have just a composite sync input and no seperated h and v sync.... With such a later 1084 ( model 1084-D ) or also the Philips CM-88.. series you shouldn't have problems.

[tomcat666]

Yeah, I saw that Philips one on the fleamarket the other day, but they guy was asking waaay too much for it (70 EUR) so I couldn't really afford it then It also had SCART on it, which would be the best thing for this....