Thanks for the reply. We know these topics (I renovated a Xa completely
once). The powersupply has been already remade two years ago and as far
as I know he did a quite good job at cleaning the connectors at the same
time. IC sockets and trimmers still are the old ones. Also the
powersupply for the 4051s on one of the control boards is still the old one.

Nevertheless our question is: exists a document, that says something
about the LEDs states while the boot up.

Florian

On 01.10.14 19:03 , '65 Lotus' Lotus@... [oberheim] wrote:
> I don't know of any error codes, sounds to me like it's just hung during
> the
> boot sequence.
>
> Step one is to check the power supply voltages. The rectifier in the
> OBXa is
> notorious for failure.
>
> If all's well, then clean and re-seat all the connector cables and pins. If
> that doesn't work, re-seat all plug-in chips.
>
> Still no good, then it's bigger problems.