Troubleshooting – Akai 14CRM,
14 inch color TV. No picture – raster OK
– no system Functions
The set switches ON, firmware
loads properly, raster appears, suddenly goes to AV mode, displaying AV on the
screen. After few seconds, this AV
display too will be out, and the set is irresponsive to any external commands,
either by remote control or by the front control panel switches.
Powered OFF the set, unplugged
it from AC mains, and re-plugged it back to AC, to check whether a hard reset
will help. No effect. The same thing as before has happened.
IC used as system
control-chroma jungle is TDA11105/PS/V3/3/AT2
System memory IC used is
24C16WP
The above mentioned symptom
mainly indicates the main system control memory IC fault. I’ve came across this type of problem, at
about 6 months back, with a Panasonic 24 inch CTV. Here I did recall it.
Anyway; I’ve to confirm the
fault before replace the memory IC.
Checked the main supply voltage to 24C16. OK. 5VDC is there.
Checked the Serial Data and
Serial Clock [SCL SDA] signal voltages.
Found fine. Shows 2.7VDC to each
of these two pins.
Checked the voltage to control
panel switch board. OK. 4.87VDC.
Checked all the micro switches
for its contact continuity. 3 out of the
6 of it have bad contacts detected.
Replaced all the 6 micros switches to make sure that they are OK.
Now I tried to control the set
by the front panel switches. Do not
control.
Checked all the pin voltages of
TDA11105; with reference to the schematic diagram. All the voltages were found normal.
Fault to main system control
memory IC 24C16WP confirmed.
Replaced it with a new one.
OK.
There was no other problem
detected.
Re-tuned the set to On-Air
transmission. Fine. Auto-search tuning is ok. Set auto tunes, locks the channels in
programs.
