exxos's Atari, Amiga & retro forum

Not actually run any 'tests' yet ...but I didn't want to remove the pcb again if it wasn't neccessary..
The PCB is now a tight fit on the metal tray since I made the large plastic seperator to replace the cardboard seperator.
Nor did I want to just link pin 16 of U203 directly to pins 7 and 10 without being certain.
So used a 1k resistor as the link.
pin 16 is now effectvely connected to other (timer_d) pins via a 1k..
tentatively booted the STe ...with the diag cart in place.
Result ...Instant menu display..
Id say that was conclusive..
yet another broken trace ...and this time very close to U203 and in the same region of the pcb where 2 other open circuit traces had been found.

A cup of tea ...then a serial port test with the dongle I made yesterday..
:D

It may well be a good idea to have a full test harness ...
can these be obtained easily ...and at what cost ?
better still can they be easily constructed ?
If so ..can someone point me at a DIY solution.
rgds

Vipersan wrote: 17 Feb 2026 11:58 Not actually run any 'tests' yet ...but I didn't want to remove the pcb again if it wasn't neccessary..
The PCB is now a tight fit on the metal tray since I made the large plastic seperator to replace the cardboard seperator.
Nor did I want to just link pin 16 of U203 directly to pins 7 and 10 without being certain.
So used a 1k resistor as the link.
pin 16 is now effectvely connected to other (timer_d) pins via a 1k..
tentatively booted the STe ...with the diag cart in place.
Result ...Instant menu display..
Id say that was conclusive..
yet another broken trace ...and this time very close to U203 and in the same region of the pcb where 2 other open circuit traces had been found.

A cup of tea ...then a serial port test with the dongle I made yesterday..
:D

Good stuff :)


:girldance: :girldance: :girldance:

Did a search for the test harness and drew a blank..
C-Alt-Rees has a video of its use..and commented on a reproduction ..but nothing out in the wild.
comments would indicate that someone had done just this in the past.
I guess this is what jonnie already has ?
I do have to wonder why this project died a death.
I guess that unless you intend repairing many Atari computers it just wasn't economically viable ?
I made my own harness for the C64...but this looks to be way more complicated....but in an era where pcb manufacture is reatively inexpensive ie pcbway etc I'm surprised that some enterprising soul hasn't recreated a version of this harness.

Someone did recreate it, but he closed his shop a couple years ago.. I tried to buy his stock of some things but I don't believe I ever got a response. I have considered making them myself but it's all the time involved in reverse engineering one and building a new one up etc.. Just not worth it.. Even more so when there is a design already out there just not accessible :(

It's probably the sort of thing @tOriman would actually do if anyone.. I don't believe used on the harnesses so far but is probably only one that would do it eventually..

@Vipersan

I got mine from a chap online, unfortunately he no longer makes/sells them. AFAIK no one else picked it up. I got mine as I was fixing quite a few ST's at the time but you probably wouldn't buy one unless you were doing the same.

This is it.


What you have is the main harness that has connectors for ACSI, Parallel, and both joystick ports. The dongles are 25 and 9 pin serial. Note there are no STE 15 pin joystick connectors or dongles meaning they always fail diagnostics. There was never an option for these.

A switchable cart came with this harness allowing for ST & Mega, STE, MSTE and TT030. I do have another diag cart that also add in the Falcon.

@exxos did talk to me about reverse engineering of the harness, but as he said, it's a lot of time and effort for something that will likely have very limited sales.

Thanks for sharing that... jonnie ...exxos
Yes indeed..I totally get why this might not be viable..certainly I would think useful to someone like yourself with a large collection to repair/maintain.
In actual fact it may be that physical plugs no longer made would be the stumbling block rather than the pcb or the logic chips..which these days could be minaturised.
Typical example being the rare 23 pin D sub on the Amiga.
Even that problem was got around by hacking down a 25 pin.
Not pretty ..but it worked.
Again..thanks for sharing.
My curiosity has at least been sated.
As a last sidenote.
Had it not been for the actual diag cart ...I would have reassembled my STe and called it done....totally unaware of any extra faults lurking.

Vipersan wrote: 17 Feb 2026 16:38 Thanks for sharing that... jonnie ...exxos
Yes indeed..I totally get why this might not be viable..certainly I would think useful to someone like yourself with a large collection to repair/maintain.
In actual fact it may be that physical plugs no longer made would be the stumbling block rather than the pcb or the logic chips..which these days could be minaturised.
Typical example being the rare 23 pin D sub on the Amiga.
Even that problem was got around by hacking down a 25 pin.
Not pretty ..but it worked.
Again..thanks for sharing.
My curiosity has at least been sated.
As a last sidenote.
Had it not been for the actual diag cart ...I would have reassembled my STe and called it done....totally unaware of any extra faults lurking.

Yes, whilst the harness does add an extra dimension, the cart on its own certainly has a place in troubleshooting and is cheap enough to be affordable by most people, plus it covers enough tests to give you a clue.

More to learn...
The pigtail to supply 5v for the SD Hard Drive is working though perhaps slightly longer would be good...but it is working.
Now I just have to learn how to use it..

Hi there!

I'm ex Manc, now living in Cheshire .

So not a million miles away from you.

Welcome !