Korg Poly800/EX800 Users

just a thought you could try removing the batteries and just using the  
power adapter in case the wiring to the batteries is a bit munted


On 13/03/2009, at 2:07 AM, TheTravelSource Fes wrote:

>
> I tested at the 9v DC in point with the A/C adapter plugged in and  
> batteries in place. The voltage came to 18V which I understood as  
> the adding of the batteries and the A/C adapter. Any thoughts as to  
> why that would/should be? Should there be a cut off of the batteries  
> once the 9v adapter is plugged into the socket? Thanks for any  
> further thoughts.
> By the way Diode 2 which prevents against reverse polarity was fine.
> -Johnb
> --- On Tue, 3/10/09, Karl Williams <williams.karl50@...>wrote:
>
> From: Karl Williams <williams.karl50@...>
> Subject: Re: [korgpolyex] Poly 800 A/C Adapter Issue
> To: korgpolyex@yahoogroups.com
> Date: Tuesday, March 10, 2009, 4:58 PM
>
> I just picked up a Poly-800 II for $15 because of the same problem.  
> I'm not sure if the design of the power input circuit is the same on  
> the MkII as the original but the culprit is usually a blown diode  
> that is meant to protect against someone plugging in a power supply  
> with the polarity reversed. If the wrong adapter is used and the  
> voltage is too high then I'd bet that the diode is dead. Another  
> part that is bypassed when the batteries are used is a filter, with  
> the part number ZJK5103-00, meant to eliminate noise in the supply (http://www.datashee 
>  tarchive. com/ZJK5103- 00-datasheet. html). If that part was  
> overloaded it might be dead too.. I had to replace both the diode  
> and the ZJK5103-00 on mine.
>
> Take care, Karl
>
> From: Gordon JC Pearce <gordon@gjcp. net>
> To: korgpolyex@yahoogro ups.com
> Sent: Tuesday, March 10, 2009 6:45:43 AM
> Subject: Re: [korgpolyex] Poly 800 A/C Adapter Issue
>
> thetravelsource wrote:
> > My Poly-800 works fine on batteries but I have not been able to  
> use the A/C adapter for years. I think someone once fried the  
> circuit with the wrong adapter or polarity and I am wondering if  
> anyone has had a similar problem and knows where to begin to repair.
>
> Are you sure the power supply is working? If it's not, then there's
> your answer. I think they're negative-to- middle, 9V - same as
> Boss/Roland/ Kawai, not like Yamaha.
>
> The power connectors on the Poly-800 (and indeed anything that uses  
> that
> type of connector) are usually pretty reliable, but tend to fail such
> that the batteries don't work and an adaptor does! What happens is  
> that
> there's a pin up the middle for one connection and a springy metal  
> strip
> that touches the outside of the plug when it's in, or another metal
> strip connected to the battery (so it acts as a switch).. The only  
> way I
> can see for the thing to work on batteries but not with a working  
> mains
> PSU is either the pin is broken, or there is a bad solder joint  
> between
> the tag with the pin and the board.
>
> > I am finding it hard to search the group messages via yahoo for  
> similar problems. Perhaps there are no other posts but if someone  
> knows of an answer on this group, please point me to it.
>
> Yahoo Groups search is knackered. Utterly useless.
>
> Gordon
>
>
>
>