virus kb no power only display backlight [solved]

hi

i've a Virus Kb with a big problem:

- power on but no sound and non-functioning checks ( keys, knob ) only display with backlight but blank.
- i've tested psu and power line and working fine,12v regular.
- I read that there is a possibility may be a condenser but I read this on the web and concerns the virus series b..I deal with telephony so I have experience in using a welder.

has someone ever had to deal with a similar problem ?

thanks