Synth-DIY Yahoo! Groups Archives

Problem with VCO Leds

2015-03-25 by juppdich@yahoo.de

Hi Folks. I´m a proud new owner of an Korg M/P, but it has got a Problem.
The Led´s on the 4 VCO do not work.
It also seems to behave a little odd sometimes with the assignment of the Voices to the VCOs but i don´t know. could also be normal. I will analyse it further and then tell you more about it.
But to the Point with the Leds: Where would be a good Starting Point for Troubleshooting?
Any Tips?
I was also not able to locate those Leds in the Scematic. Maybe because the Part where the VCOs are drawn has bad Detail Quality in the Scematics.

-Voltages seem ok so far (except -15V is @ 14,91V and in the Service Manual there is stated something about +- 0,01V). I Guess that would not cause the VCO Leds to fail.

Best Regard - Juppdich

Re: [korg_mono-poly] Problem with VCO Leds

2015-03-25 by Florian Anwander

Hello Juppdich

Am 25.03.2015 um 18:25 schrieb juppdich@yahoo.de [korg_mono-poly]:
> I was also not able to locate those Leds in the Scematic. Maybe 
> because the Part where the VCOs are drawn has bad Detail Quality in 
> the Scematics.
The LED is D103/203/303/403

To locate them in the schematic of KLM354 
(http://fa.utfs.org/diy/korg_monopoly/mp_06_klm-354_vco_schemo.gif) have 
a look at the right side of the plan. There are the gate inputs. Track 
the line of Gate 1. It is routed to an OpAmp 4558. At its output a 
resistor leads to two diodes in series. The second one of these two 
diodes is the LED.

Florian

Korg Mono/Poly

Problem with VCO Leds

Problem with VCO Leds

Re: [korg_mono-poly] Problem with VCO Leds

Move to quarantaine