On Wed, Aug 31, 2016 at 10:53:11AM -0700,
jkbarnes@... [korgpolyex] wrote:
>
> 1. Whenever I turn the power off to the synth for longer than about 10 minutes, it loses all its programming. This happens WITH the C-cells still in it. I believe this has something to do with component C88 being removed but I'm not sure. I have ordered the Hawk800 + Atomahawk mods. My understanding is that the mods negate the need for any sort of battery powered memory so do I even need to fix this issue? If so can someone help me ID that component? I'm having a hard time reading the schematic....
>
The circuit diagrams are readily available (but pretty damn poor quality).
C88 is a 47μF 16V electrolytic, on the diagram it's beside the 6116 memory IC.
The value is not critical. It provides a bit of power to IC21 when there is no mains supply and no battery. The voltage probably isn't too critical either, but at least 16V will be "about right".
>
> 2. AC power won't work. Component D2 has been reduced to ash near the AC adapter. There also appears to be some more ham-fisted soldering and I can't tell if there is more wrong than just the burnt component. Can you guys take a peek at the attached picture and let me know what you think? Do I just need to replace component D2? I picked up some 9.1v zener diodes but can someone confirm that this is the proper component?
D2 is a protection diode that links the centre pin of the on/off switch and the "sleeve". It's "backwards" because it should conduct when you put a positive-centre power supply in to stop the rest of the circuit getting zapped.
Guess what's most likely happened?
So to solve that problem you're likely to need to check out Q1, D4 and friends which is a 9V regulator in the ∗negative∗ rail coming from the power supply.
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Gordonjcp MM0YEQ