Thursday, September 4, 2014

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TROUBLESHOOTING SANYO LCD 19R30 19 LCD TV

No raster_Sound normal, but no picture_ Picture normal, but no sound_Some source channel work abnormally.
No raster (screen is not lit), no picture, no sound
  If detect NS01 (main chip) pin 169 is of high level, you may remove RS14, detect VS01 emitter if first output high level after power on, then output low level continuously. If not, the reset schema may have problem. First detect if NS01 (main chip) pin 44 waveform is sine wave, if not, check NS01 crystal oscillator schema. When checking periphery of NS01, NS02 and NS05, check relative component’s welding, then use oscilloscope to detect the joint resistor pin between NS01 and  NS05.  If  the  waveform  is  not  regular  square-wave,  that  means  either  NS01  or  NS05  work abnormally and therefore cause address line and data line be in error. NS05 error probability is greater. In addition, if joint resistor between NS01 and NS05 is in error, it will also cause no raster, no picture and no sound.
CLICK ON THE PICTURES TO ZOOM IN
Sound is normal, but no picture.  (Blue screen and OSD can be displayed.)  Note: HDMI channel is excluded.
Sound OK, but no picture (only backlight lights up)
Picture normal, but no sound.
Some source channel work abnormally.
Note: To get normal HDMI picture, especially when connect to DVD player with HDCP information, it must be guaranteed that NV04 and NV05 (HDMI port DDC chip) writing is correct, and especially bus between NV04, NV05 and HDMI jack must be smooth and unhindered. Secondly HOTPLUG schema must be guaranteed (it is of high level at normal broadcast), otherwise the picture playback cannot be normal.
To get normal HDMI sound, especially when connect to DVD player with HDCP information, it must be guaranteed that NV04 and NV05 (HDMI
port DDC chip) writing is correct, and bus between NV04, NV05 and HDMI jack must be smooth and unhindered, otherwise the sound playback cannot go.

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