> Good call. I checked the pot and there was a spot that was questionable in touching the > faceplate. Cleaned it up and it's working great. Splendid! > NOW seeing as you are that good with schematics, any idea why the Both Saws > and Square wave will not work on OSC 1 of my EML 101? (Triangle and pulse work) ;) If you look at the schematics for the 101, page 6 has VCO1. The squarewave output circuit is in the top right of the page. It goes to the sawtooth wave reset circuit, so if the square wave is dead, you get no sawteeth either. I assume the squarewave also goes to the waveform selector switch, but it's not shown on the schematic. The triangle is OK coming out of the 748 opamp, so it's either the block marked "S.T." (presumably schmitt trigger - a squaring up circuit), the transistor buffer (the bit with the circle drawn around it) or the wiring. I've never been inside a 101, so I can't take you very far. Also, I don't know your level of electronic ability, so let's start with the easy stuff. Unplug the juice and trace the wire from the square position on the VCO1 waveform switch back to board 2. I'm guessing there should be two wires off the square output of the board - one to the switch and one linking to the sawtooth reset circuit. Check that they haven't broken off. Also check that neither wire are shorted to ground, especially at the switch. If they're OK, the next most probably cause is the two transistors with the circle drawn around them. That circle implies that someone has had a problem here before, and it's not a well protected circuit. If you don't know how to check the transistors, then it's a job for a tech. If the two transistors are OK, then the last place to check is the "S.T.". I'd guess that the circuit is going to be the same as the one shown on the VCO2 schematic on page 7. Again, unless you have some electronics knowledge, it's a job for a tech, but if you feel brave you could check under the board for dry (cold) joints or broken tracks - but try not to snap any wires off the board. That's all the help I can offer... Steve
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RE: [emlsynth] Re: OSC 2 blowing fuse on EML 200
2007-10-05 by Steve Ridley
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