Self-making an Amiga video cable

Eamoe · 03 May 2011, 23:23

Hi all,

have a Commodore DB23F to DB9M video cable that has a cut Blue GND lead. Impossible to repair, the wires at the ends are trapped in the molded rubber of the connectors.

Hence my will to make my very own cable with to-solder connectors and appropriate hoods.

Question: should I use a special cable (shielded / coaxial...)? Or will just any cable with the sufficient number of leads in it do the trick?

prowler · 03 May 2011, 23:33

Hi Eamoe,

Shielded cables are recommended for video signals. However, I have often made up (short) cables with insulated, but unshielded, 14-stranded wire for testing purposes and have never had a problem with interference.

If there are any audio cables to be routed simultaneously, then I would advise you to shield one from the other, as audio signals can cause video interference through crosstalk.

Jope · 06 May 2011, 14:08

I recommend you get some video cable that has coaxial connections inside for at least the RGB signals.

Having said that, I have had success with just straight wires when I've made these in a pinch. TV frequency signals aren't exactly that fast, but a proper cable will help you get the best possible picture.

Eamoe · 06 May 2011, 16:14

Thanks on your replies here. I'm ignorant of cables and their different flavors. Particularly, there's one thing I don't understand. I've always thought (and a quick Wikipedia run temporarily confirms this) that coaxial only existed in 2-conductor configuration. Is this to say that I would then need three coaxial cables (3 color signals + their respective GND)? Or are there cables with numbers of coaxial "lines" already included?

Inspection of the dead Commodore cable shows that there is only 1 conductor which could be called "coaxial", and that's one big weaved conducting "tube" enclosing all the other "regular wires", insulated in various colors.

Also, what's the point in using a cable that's coaxial when your connector is not (DB-style)? Does this not ruin all, or part of the benefit of coaxial configuration?

I gotta learn...

Jope · 06 May 2011, 17:23

Yes, the inside of the coax wire goes to the signal and the sheath goes to ground. As it happens, there is a separate ground for each signal in the DB23 connector, but IIRC they are simply tied together in the computer.

And you are right, the connectors on both ends hurt the signal, but it's still better to have coaxial cable for some of the signal than none at all. For it to be properly implemented, there should be impedance matched coaxial connectors on both ends (such as BNC).

Eamoe · 10 May 2011, 12:47

I ordered the stuff to build the cable. It's only after receiving the parcel that I noticed these guys actually make Amiga monitor cables.

http://www.connectworld.net/cgi-bin/ccc/05MCAmiga.html

Anyway, it's gonna be fun to build my own!

Hewitson · 10 May 2011, 13:52

I wish I considered making cables fun!

kipper2k · 10 May 2011, 13:59

Nice to see they still sell the 23 pin connectors. (not cheap mind you, but available is good

. For your cable you can use an old serial or parallel PC cable, they are normally shielded so its just a case of selecting the wires you need

pandy71 · 10 May 2011, 18:31

Quote:

Originally Posted by Eamoe

Question: should I use a special cable (shielded / coaxial...)? Or will just any cable with the sufficient number of leads in it do the trick?

triple or quadruple 75 Ohm, coaxial, cable usually dedicated for SCART or VGA (VGA will be more than OK with respect to video signal integrity)

Eamoe · 10 May 2011, 20:16

Quote:

Originally Posted by Hewitson

I wish I considered making cables fun!

Well, I'm taking my soldering fun where I can... I mean, sure I can't solder SMD, but then...

tygre · 30 May 2011, 00:56

Dear all!

I would like to build an extension cable for the Amiga video. I have a male and a female DB23 connector. I am wondering if I really do need to connect all the pins to make the extension or if only some of the pins are needed to plug the Amiga to an external scan doubler, which is then connected to a VGA monitor?

Thanks!
Yann

Jope · 30 May 2011, 09:42

R, G, B, grounds, voltages, hsync, vsync, csync

Optimally you would have a cable with coaxial connections for each colour + sync signal.

Don't be too disappointed when your image quality goes down.

tygre · 30 May 2011, 15:10

@Jope

Thanks a lot! I'll try out and keep you posted!
Yann

03 May 2011, 23:23	#1
Eamoe Stunt Car Racer Vet Join Date: Mar 2006 Location: Vevey/Switzerland Age: 44 Posts: 145	Self-making an Amiga video cable Hi all, have a Commodore DB23F to DB9M video cable that has a cut Blue GND lead. Impossible to repair, the wires at the ends are trapped in the molded rubber of the connectors. Hence my will to make my very own cable with to-solder connectors and appropriate hoods. Question: should I use a special cable (shielded / coaxial...)? Or will just any cable with the sufficient number of leads in it do the trick?

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03 May 2011, 23:33	#2
prowler Global Moderator Join Date: Aug 2008 Location: Sidcup, England Posts: 10,300	Hi Eamoe, Shielded cables are recommended for video signals. However, I have often made up (short) cables with insulated, but unshielded, 14-stranded wire for testing purposes and have never had a problem with interference. If there are any audio cables to be routed simultaneously, then I would advise you to shield one from the other, as audio signals can cause video interference through crosstalk.

06 May 2011, 14:08	#3
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,918	I recommend you get some video cable that has coaxial connections inside for at least the RGB signals. Having said that, I have had success with just straight wires when I've made these in a pinch. TV frequency signals aren't exactly that fast, but a proper cable will help you get the best possible picture.

06 May 2011, 16:14	#4
Eamoe Stunt Car Racer Vet Join Date: Mar 2006 Location: Vevey/Switzerland Age: 44 Posts: 145	Thanks on your replies here. I'm ignorant of cables and their different flavors. Particularly, there's one thing I don't understand. I've always thought (and a quick Wikipedia run temporarily confirms this) that coaxial only existed in 2-conductor configuration. Is this to say that I would then need three coaxial cables (3 color signals + their respective GND)? Or are there cables with numbers of coaxial "lines" already included? Inspection of the dead Commodore cable shows that there is only 1 conductor which could be called "coaxial", and that's one big weaved conducting "tube" enclosing all the other "regular wires", insulated in various colors. Also, what's the point in using a cable that's coaxial when your connector is not (DB-style)? Does this not ruin all, or part of the benefit of coaxial configuration? I gotta learn...

06 May 2011, 17:23	#5
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,918	Yes, the inside of the coax wire goes to the signal and the sheath goes to ground. As it happens, there is a separate ground for each signal in the DB23 connector, but IIRC they are simply tied together in the computer. And you are right, the connectors on both ends hurt the signal, but it's still better to have coaxial cable for some of the signal than none at all. For it to be properly implemented, there should be impedance matched coaxial connectors on both ends (such as BNC).

10 May 2011, 12:47	#6
Eamoe Stunt Car Racer Vet Join Date: Mar 2006 Location: Vevey/Switzerland Age: 44 Posts: 145	I ordered the stuff to build the cable. It's only after receiving the parcel that I noticed these guys actually make Amiga monitor cables. http://www.connectworld.net/cgi-bin/ccc/05MCAmiga.html Anyway, it's gonna be fun to build my own!

10 May 2011, 13:52	#7
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,773	I wish I considered making cables fun!

10 May 2011, 13:59	#8
kipper2k Registered User Join Date: Sep 2006 Location: Thunder Bay, Canada Posts: 4,323	Nice to see they still sell the 23 pin connectors. (not cheap mind you, but available is good . For your cable you can use an old serial or parallel PC cable, they are normally shielded so its just a case of selecting the wires you need

30 May 2011, 00:56	#11
tygre Returning fan! Join Date: Jan 2011 Location: Montréal, QC, Canada Posts: 1,438	Dear all! I would like to build an extension cable for the Amiga video. I have a male and a female DB23 connector. I am wondering if I really do need to connect all the pins to make the extension or if only some of the pins are needed to plug the Amiga to an external scan doubler, which is then connected to a VGA monitor? Thanks! Yann

30 May 2011, 09:42	#12
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,918	R, G, B, grounds, voltages, hsync, vsync, csync Optimally you would have a cable with coaxial connections for each colour + sync signal. Don't be too disappointed when your image quality goes down.

30 May 2011, 15:10	#13
tygre Returning fan! Join Date: Jan 2011 Location: Montréal, QC, Canada Posts: 1,438	@Jope Thanks a lot! I'll try out and keep you posted! Yann

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