From yahoo Sent Sat, May 2nd 2015, 14:35
From yahoo Sent Sat, May 2nd 2015, 14:35
> Hi Dieter,
>
>
> Ok I have done some more troubleshooting. Once separated again, the A-155 still doesnt output a trigger in one of the
> LC3 cases (the ones with he power adaptor) but it does work in the LC 9 and LC base which have a direct mains connector.
> It also works fine as soon as another socket on the a-155 is plugged into a module in any of the other cases which seems
> to me a grounding issue but I dont know why!
>
> Neil
Hello Neil,
I took a look at the technical records (schematics, pcb layout) and there should be no problem (i.e. the sockets of the trigger
outputs should be grounded). But I also took a look at a A-155 module and indeed the four trigger sockets are not connected to GND.
I traced the GND signal and found the error: the 10 pin connector on the long trigger board which is used to connect the small board
has no GND. It's mysterious because our technical records say that the connector is grounded. I suppose that the fault occured a few
years ago when the pcb manufacturer told us that they are not able to manufacture the pcbs from the old documents any longer (the
A-155 was developed nearly 20 years ago on an Atari system). But they mentioned that it's possible to scan the old films so that
they can be used in the future. I suppose that during this procedure the fault happened. During the test of the A-155 the missing
GND of the trigger sockets is not recognized as the modules are tested in combination with other modules in the same frame (i.e.
with the same common GND). The fix is very simple: on has to connect one of the pins of the 10 pin connector of the trigger board to
GND. The GND track is just next to the pin so that a small solder blob solves the problem. I'll prepare a document that show the
position of the required solder connection. I'm quite sure that older A-155 (manufactured directly from the Atari data) do not have
this problem.
Best wishes and sorry for the troubles
Dieter Doepfer
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