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: 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
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korg poly 800 power problem
2010-12-23 by n8