[sdiy] Repair help Waldorf Chord Gekko

[Sam Ecoff]

Hi Peter,

Interesting stuff. Mine never fell or took a hard drop. I'm trying to use it with a Fatar SL880, but I know that it works with that keyboard as I always used to use it with that keyboard with no problems. Every aspect of the Fatar works perfectly, so I have no reason to suspect that it is suddenly not putting out the necessary power to power the gekko. Maybe it would be worth trying to replace the crystal. It might also be worth trying to reseat the PIC in case it has somehow come loose. I notice that it is wedged into two 16 pin dip sockets soldered side by side, and not soldered very flat to the PCB. 

I'll let you know if I make any progress.... thanks for the help.

Sam E.

On Apr 22, 2011, at 2:49 PM, Ullrich Peter wrote:

> Hi Sam!
> 
> Thank you very much for the pictures. Very interesting!
> 
> The design of the old Gekkos was very simple and quite cheap but it could be copied by everyone as the eproms could not be copy protected.
> 
> The new design with the PIC can be copy protected - so a big benefit from the manufacturer side.
> And you can reprogram the chip "incircuit" - I bet that the 5 edge contacts are the incircuit programming interface.
> Eproms can not be reprogrammed incircuit...
> 
> Of course it would have been possible to make a newer version out of the 8031 design by using one of the 87C51 or 89S82 single chip 
> microcontrollers but maybe they also made some software improvements that were easier to program on the PIC platform.
> 
> So in your case I don't think that the PIC has lost its program, I have never heard that this happened. I think that there is another problem.
> Maybe the crystal is damaged (did your Gekko fell on the floor too hard?) or there maybe a problem with the power supply.
> 
> The original Gekkos also had the problem that they didn't work with all keyboards as some keyboards have a midi output circuit that
> is different to the circuit recommended in the MIDI kompendium. And so the Gekkos wasn't able to get the power and MIDI data at the same time.
> The little Fatar Studio 49 master keyboards for example don't work with the Waldorf Gekkos...
> 
> Ciao
> Peter