SM124 cable

[alexh]

Just having an interesting discussion over at Atari Forum about repairing an SM124 that has had the 13-pin DIN connector cut off.

https://www.atari-forum.com/viewtopic.p ... 17#p463417

My experience of other electronics is that cables, especially captured cables, don't always follow a standard internal colour coded wiring. Is that anyone else's experience?

It should be possible to work out which is the audio pretty easily by trial and error but the other 3 wires (Mono + HSync + VSync) there are 8 combinations. And I don't know what would happen if you connect up the wrong ones.

While I don't like recommending opening up monitors I think that would probably be the easiest way?

https://docs.dev-docs.org/htm/search.php?find=sm124

The MT-21 revision of SM124 has two connectors one (P301) for Mono video the other (P602) for Audio, Hsync and Vsync
The MT-9 revision of SM124 has one connector (P301)

There is a hint in this post of the wiring colour for an MT-21

https://www.atari-forum.com/viewtopic.php?t=42084

P602 = Red, Yellow, Green and Shielding
P301 = Coax with mono being the core and shielding being ground

Anyone experience with servicing SM124? Maybe has one open on the bench now?

[alexh]

Someone in the other thread posted links to better PDFs than I included so I've deleted the attachment

[exxos]

My experience of other electronics is that cables, especially captured cables, don't always follow a standard internal colour coded wiring. Is that anyone else's experience?

I can't even remember having any cable which followed any sort of colour coding. Last cables I worked on were PS2 cables. Even if they had the same coloured wires, they would vary where they went batch to batch. Sometimes all but 1 colour would be the same, but even that would never tally.

[rubber_jonnie]

Personally I never use colour coding as a guide as it seems to be the case that manufacturers use 'the cheapest cable available at the time of assembly', leading to mismatches between the varying versions.

I would always buzz out based on schematics and pinouts and connect appropriately.

[alexh]

What you're writing is my experience too. NTSC (Never twice same colour) applied to cables as well as TV pictures :D

But I was just curious if anyone had one open on the bench what theirs is like?

[rubber_jonnie]

What you're writing is my experience too. NTSC (Never twice same colour) applied to cables as well as TV pictures :D

:lol: Very true!

But I was just curious if anyone had one open on the bench what theirs is like?

Sorry, I don't have much in the way of CRT stuff these days, just not enough space.