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Subject: RE: [korgpolyex] Re: korg poly 800 power problem

From: "backshall1 \(dsl\)" <backshall1@...>
Date: 2010-12-27

Yes, it should be lower than that if the 5V regulator section was working, so that's a pretty good indication that no power is getting through at least one of the power transistors. I'm digging out the schematic now.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of Michael Hawkins
Sent: Monday, December 27, 2010 9:36 AM
To: korgpolyex@yahoogroups.com
Subject: Re: [korgpolyex] Re: korg poly 800 power problem

 

the original email said that the voltage was still 13 volts while plugged in to the Poly.

From: backshall1 (dsl) <backshall1@...>
To: korgpolyex@yahoogroups.com
Sent: Sun, December 26, 2010 10:24:41 PM
Subject: RE: [korgpolyex] Re: korg poly 800 power problem

 

A newer switching supply wall wart will give you a consistent 9vdc regardless of current flow, but an older one with a big transformer will be 12-13 volts when there isn't much power being used, and drop to 9v when you are using the rated current. I've used ones that measure 12-13 volts without any problems.
 
Don B.

From: korgpolyex@yahoogroups.com [mailto:korgpolyex@yahoogroups.com] On Behalf Of korgpolyex800
Sent: Sunday, December 26, 2010 9:58 PM
To: korgpolyex@yahoogroups.com
Subject: [korgpolyex] Re: korg poly 800 power problem

 



The wall wart should be providing a consistent 9V DC output.

If you're seeing 13 volts at the input of the Poly 800 then you need to get a 9V DC wall wart. 13 volts will overload the on board power supply control circuits.

Mike

--- In korgpolyex@yahoogroups.com, "n8" <natere2ster@...> wrote:

>
> hi list.
>
>
just joined and have a question perhaps someone can chime in on...
>
> i have a korg poly 800 mkI here on the bench with a power
issue.
>
> when on batteries it runs fine, but will not run off the
wall wart...
>
> the wall wart works ok, i tested the voltage on
the dc plug and it is spitting out 13V const. I read that at the DC jack as well...
>
> The problem so far looks like i do not get the +5V on
the connector CN06A on pin 10....is that correct?
>
> I get the
pull DC in on pin 11 so that is good!
>
> But i need to get that 5V
on pin 10 so it can be sent to the chorus board, then to the volume / switch on?
>
> from the rough schematics i see that Q1's base and
collector are tied to this rail, and its emitter is tied to the DJ jack....
>
> Q3 is E-C is on the 5V line, and its base is tied to
Q2 tranny which is tied to Q15 which is tied to gnd.
>
> Is this
correct?
>
> I assume its one of the power switching transistors
are bad, how can I confirm this? I de-soldered Q1 and have it on the breadboard.
>
> I used the standard transistor PNP tester circuit,
as seen here:
>
>
href="http://www.kpsec.freeuk.com/trancirc.htm" target=_blank>http://www.kpsec.freeuk.com/trancirc.htm
>
> It seems to work fine, I can turn the led on when the switch is closed
and turn it off when its open...
>
> So i guess its ok and i should
put back LOL?
>
> Anyone know of any other transistors to
check?
>
> I am looking at Q3 for some reason....
>
>
What steps down to voltage from the DC jack in out to the +5V?
>
>
I assume once i get the +5V i will be ok...
>
> i just keep looking
at Q1 and Q3 cause they are both tied into GND, the DC jack in, and the +5V rail.....
>
> Sorry for all the questions i am noob!
>
> Cheers,
>
>
Nate
>