K5synth

Check if the tranformer outputs are normal (I assume about 18V 
alternating current RMS - about 40 volts peak-to-peak). Then check if  
there is stable DC voltage at the input of the voltage regulator 
chips. It should be about 15 to 20 volts with only about 100 
millivolts ripple on it.  There may be several regulator chips; one 
for each voltage like +5V, +12 and -12 volts are the most common.  If 
there is no output voltage on the output pin of any of the regulator 
chips, I would guess that something is shorting the voltage to ground. 
If you shake the box, does anything rattle?  It may be a piece of 
metal.  Is the transformer hot? There may be a short inside it.  Is 
there a lot of ripple voltage on the DC output after the transformer 
but before the voltage regulator chips?  Test the diodes or bridge 
rectifier.  Maybe the big filter capacitor has gone bad.


  Usually the actually electronic sound generator chips are last to go 
bad.  Usually the main power supply is the first component set to 
fail.


 




--- In k5synth@yahoogroups.com, "tuff_gnarl_69" <tuff_gnarl_69@y...> 
wrote:


> Hi, my name is Nicolas, i´m from Argentina and


> i own a Kawai K5 synthesizer. The unit has been


> working perfectly for the last 15 years, but today i


> couldn´t turn it on. I opened the unit and checked all


> the fuses and they were fine. Then i checked the


> transformer and it was recieving current but when i


> checked the regulators on the front panel none of them


> had V on their outputs. I don`t want to mess around


> with it unless im sure what im doing.


> I´d be grateful if someone could provide me the


> schematics, so i could repair the unit, its far too


> expensive for me to send it back for tech support. Any help would be


> welcome.


> Thanx a lot.


> Nicolas