[sdiy] korg poly 800 power problem

[Oren Leavitt]

On 12/21/2010 9:00 PM, Nathan M. Reeves wrote:
> hello&  happy holidays synth nuts!
>
> i am having a heck of a time following the schematics for my poly 800....
>
> the problem i am experiencing with this unit is that it will turn on and run fine on the batteries ( 8x C cell 1.5V) but when the batters are out and I plug in my korg adapter wall wart, it will not power on.
>
> I am looking at the schematics and cannot tell where to test the voltages that are input from the dc jack.
>
> DC jack =>  GND and hot goes to 5-11B?  looks like there is a diode D2 between the GND and hot connection....
>
> the power switch is VR4, and i cannot find it anywhere on the schemo
>
> so if the battery powers the unit but the dc jack input does not, what and where can i probe to find the faulty component / short?
>
> sorry i have looked over the schemo for an hour now and my head hurts (so scrunched and tiny!)
>
> i was hoping it was a blown fuse or the like...i am used to keyboards with IEC plugs that go to fuses, diode bridge, filter caps, etc that you can then test to see if the power rails are all in spec.
>
> this is new to me....
>
> any advice will be appreciated!
>
> if anything i will just run off the battery!
>
> cheers!
>
> nate
>
>

Happy Holidays to you too!

As a first check, does your wall wart put out the proper voltage with a 
full rated load applied?
A failing power supply is possible...esp if the wall wart is a switcher.

- Oren