[sdiy] Akai Z8 issue

[Rutger Vlek]

Dear all,

I'm currently working on a rather modern Akai Z8 sampler with came in with a malfunctioning output. A problem I thought would be a simple one, but it's turnout out to be much more than just a simple problem. As I'm working without a service manual, I have unmounted the analog board and drawn a simple schematic of the signal path to each output, upon which I planned to mount it back and trace the signal with a scope to where it stops. If the world would only be that simple.... It turned out the unit would not longer produce audio at all, only digital blurps of randomness (at full scale volume!) and on all channels the same. As CPU board and analogue board are coupled by some fairly fancy (and fulnerable looking) SMD board-to-board connectors, I resoldered all of their joints. No success... My second guess was an invisible crack in the PCB or a badly soldered SMD IC, so I started poking around with a non-conductive rod, to see if I could hear any responses to my actions. The only thing that clearly responds is a set of ferrite inductors near the CPU-to-analog PCB connectors. When I touch them the digital noise changes noticably into different patterns, more continuous noise, whining, etc. So these are on my list to investigate next, but I don't feel that's going to be the main source....

Does anyone have a service manual for the Akai Z8? Or other suggestions on where to proceed?

Regards,

Rutger