Display not working (and no Audio) FIXED !

I Have fixed the display problem on the 780 without requiring the Service Manual, but by using a schematic..

The 9 Volt cct that powers the display's LCD graphics (NOT the backlight, which runs on 12 vdc) WAS NOT working. If your LCD graphics are out AND you do not get any signal audio (you may still hear audio hiss or "screaching" though)....the Zener diode that supplies the reference for the 9 volt cct is likly burnt out. This 
Zener diode D27 is a UDZ10. It's a small surface mounted chip, close to the Q2 transistor. This diode is a 10 volt zener (not 9v, as it goes through a resistor) UDZ10 zener. Any suitable sub should work.

Hope this helps anyone with LCD display problems/ NO RF audio problems.

Greg
VA3VFO

--- In [email protected], "gregtheham" <radiotrade@...> wrote:
>
> Does anyone have a link or file for the 780 (or hand-held version) Serivce Manual? I Have Schematics, which has been a big help. Service may help tracing my problem though. 
> 
> BTW, I have lost LCD display (Backlight still OK) and RF signal Audio.
> I am getting 12VDC where required to drive 12v ccts, but suspect a 9v problem. The 2SD1667 tests OK (the one on the plug-in pigtail and mounted to the chassis), but Q2 has 12VDC on its output, which I believ should be 9V via the zeiner D72...this controls Q4 for the 3V ccts,and that seems OK..( I am getting 3v from it) but that seems to confilict with my idea of Q2 and/orD72 not working...I dont think I would get 3v
> 
> I also want to trace what is referred to as SW B, but cant find what that is...( IC controled Softwware switch from main processor?) cant find any origin for it, althoughmany ccts show as continuing on to SW-B
> 
> Can anyone help?
> 
> Thanks
> Greg
>