Doepfer

Thanks Dieter, at least I know I'm not going crazy now!

Neil

Sent from my iPhone

On 2 May 2015, at 15:35, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:

>> Hi Dieter,
>> 
>> 
>> Ok I have done some more troubleshooting. Once separated again, the A-155 still doesn’t 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 don’t 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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