[sdiy] Fixing a Junost 21

[Gorka Garcia]

A friend recently bought a Junost 21 (picture here: http://blog-desorden.blogspot.com/2008/01/keytar-night.html specs and schematics here: http://www.ruskeys.net/eng/base/unost21.php ) which does not work. It seems to power up and you can even hear some very low sound out of it sometimes. So I have it at home to see if I can get it to work. It is the first time I get into such a project and would like some advice from the experts about where to start looking.

So far I have checked the following:

Power supply: seems to be giving the right voltages (+/- 10V)
Visual inspection: There seems to be a blown capacitor in one of the voices and a short cut in a couple resistors in another voice circuitry (which seems to be done on purpose by a previous attempt to fix something in it). There is also a strange "fix" in one of the PCB, with a transistor replaced with a resistor ¿?¿?¿?¿ (VT1 in here: http://www.ruskeys.net/pasp/unost21/c/uncxem7.jpg Any clue of what this board does or what does it say in that image?). 

Hopefully I will have more time to look into this over the weekend and can give you more info.

Thanks in advance,

Gorka


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My blog: http://blog-desorden.blogspot.com/

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