Balls, the schematics for the Ferguson MA-20 have arrived and its clear why mine doesnt work. Its expecting 12V FROM the monitor on the central pin in the DIN connector. None of my monitors present such a voltage!
Guess I will have to modify them in some way - theres bound to be 12V somewhere in there. Might have to mount a 12V power output on the back of the monitor and make a Y cable for it to work.
As it so happens, I took delivery of a box of various Speccy bits today - some of it was rubbish headed for the tip, but amongst it all, was a "Ferguson RGB Interface" - it is quite a chunk of plastic - has a through connector and even a Spectrum-esque logo on it.
I have not tested it as I lack a suitable RGB monitor.
Anyone interested - you can have it for ?8 including UK p&p
Originally Posted by Womble
Balls, the schematics for the Ferguson MA-20 have arrived and its clear why mine doesnt work. Its expecting 12V FROM the monitor on the central pin in the DIN connector. None of my monitors present such a voltage
That?s an interesting discovery you?ve made there Womble. Many moons ago I bought one of these MA-20s from ebay and like you could not get it to work. Do you know what the other pins are for? Mine has a 8 pin DIN plug.
I have the manual but as you say it doesnt mention pinouts, the service manual does so here goes.
1 - Ground
2 - Composite Sync
3 - Green
4 - Unused
5 - Blue
6 - Sound output from pass through
7 - Red
and finally that central pin.
8 - 12V FROM monitor.
If there is no 12V on this pin the RBG adaptor stays in monochrome mode, if it sees the 12V it passes it to the onboard voltage regulator to give the 5V the device needs. In mono mode it derives this 5V from the 9V available on the Speccy edge connector.
Thank you Womble and Geoff for the information of the pin out for the MA-20. I?m not sure how to get round it needing a 12v supply. I might try connecting an external 12v power supply just to see if I can get it to work in RGB mode.
When I have a moment I will scan the service manual - its only 4 A4 pages, am amazed I managed to find it so I reckon it should end up stored for posterity and for the benefit of all in the WoS doco archives.
When I have a moment I will scan the service manual - its only 4 A4 pages, am amazed I managed to find it so I reckon it should end up stored for posterity and for the benefit of all in the WoS doco archives.
Excellent,
I scanned the 8 pages of the MA20 manual but when I tried to make a pdf in Google Documents they were a bit off-centre. They are here to read. A few need cleaning but if anyone wants to try a pdf feel free.
Am happy to report it works and works well when fed those missing 12 Volts on pin 8. Piccy shows it in action - a bit of a heath-robinson tangle, but wanted to test it before I bought parts to make a neater solution.
Colour fidelity is also rather good too - the yellow looks like it might be a tad more mustardy than the original spec yellow but only just - everything else seems spot on!.
Comments
Guess I will have to modify them in some way - theres bound to be 12V somewhere in there. Might have to mount a 12V power output on the back of the monitor and make a Y cable for it to work.
Again I say it, "Balls"
do you want it to be connectable on edge connector or you will connect yourself it to Speccy (YUV lines and 5V, GND)?
Second solution will give better pic, but need to open machine and solder some lines - not for everyone.
I will try in any case to lower noise on UVY lines when edge connector is used - maybe adding some resistors on adapter will do it...
And a request more: can be connector on the end of this adapter compatible with 128k's RGB output, because I already have that cable : )
I have not tested it as I lack a suitable RGB monitor.
Anyone interested - you can have it for ?8 including UK p&p
www.rwapsoftware.co.uk
www.sellmyretro.com
I also would prefer an edge connector
That?s an interesting discovery you?ve made there Womble. Many moons ago I bought one of these MA-20s from ebay and like you could not get it to work. Do you know what the other pins are for? Mine has a 8 pin DIN plug.
This is the label on the back of my Ferguson MC01 monitor
http://gwearmouth.googlepages.com/pinouts.JPG
and these are the sockets
http://gwearmouth.googlepages.com/jacks.JPG
You could get an MA11 monitor lead to connect the interface to Ferguson monochrome monitors MM02 (green) and MM06 (amber) monitors.
The central pin seems to be unused.
The pinouts are not mentioned in the manual which I will scan.
1 - Ground
2 - Composite Sync
3 - Green
4 - Unused
5 - Blue
6 - Sound output from pass through
7 - Red
and finally that central pin.
8 - 12V FROM monitor.
If there is no 12V on this pin the RBG adaptor stays in monochrome mode, if it sees the 12V it passes it to the onboard voltage regulator to give the 5V the device needs. In mono mode it derives this 5V from the 9V available on the Speccy edge connector.
Excellent,
I scanned the 8 pages of the MA20 manual but when I tried to make a pdf in Google Documents they were a bit off-centre. They are here to read. A few need cleaning but if anyone wants to try a pdf feel free.
http://gwearmouth.googlepages.com/rgb1.jpg
http://gwearmouth.googlepages.com/rgb2.jpg
http://gwearmouth.googlepages.com/rgb3.jpg
http://gwearmouth.googlepages.com/rgb4.jpg
http://gwearmouth.googlepages.com/rgb5.jpg
http://gwearmouth.googlepages.com/rgb6.jpg
http://gwearmouth.googlepages.com/rgb7.jpg
http://gwearmouth.googlepages.com/rgb8.jpg
I'll clean them tomorrow.
Colour fidelity is also rather good too - the yellow looks like it might be a tad more mustardy than the original spec yellow but only just - everything else seems spot on!.