Troubleshooting For Audio/Keyboard - RCA 50LB45RQ Service Manual

4.3 Troubleshooting for Audio
Note: Comparing with the display problem, the audio malfunctions are easier to work out. Constantly, if you have excluded
the possibility of bad speakers and bad connection of audio output, the problem generally comes from the audio processing
parts of mainboard. Please change mainboard for a try, or refer to chapter 5 for further information about repairing.
No Sound
o Check whether the speakers are broken first.
o Check the wire that links the mainboard and speakers. Watch if there is fracture or cladding material breakage.
• Check the joint of speakers and audio wire, watch if there is poor soldering or fake solder. Besides, the polarity mistake
can also lead to audio problem.
Volume too low
o Check whether there is a jam at the sound hole in front cabinet.
• Check whether one or more speakers are bad.
Sound channel loss or confounding
• Check whether the audio wires are installed reversedly. The left channel wire should be white and the right channel wire
is red.
• Check the audio output socket of mainboard to see whether it is wrongly inserted. If not, the mainboard audio output module
may be bad, refer to chapter 5 for more details and resolution ways.
• If the connection is stable and right, the mainboard audio output module may be bad, refer to chapter 5 for more details
and resolution ways.
Noise
o Check if there is anything should not exist in the speaker hollow space (such as screws).
• Check if the antihunting EVA is broken or missing.
• Check if the speakers are bad.
4.4 Troubleshooting for Keyboard
No key can work
e Check the wire between mainboard and keyborad, watch if there is fracture or cladding material breakage.
• Check the joint of mainboard and keyboard wire, watch if there is poor soldering ofrfake solder.
• Check the resistances that locate on the keyboard PCB. Watch if there is wrong or broken ones. Also, the poor soldering
of fake solder should be concerned and checked carefully.
o Check the other components of keyboard(such as capacitances and microswithes) are wrong or bad.
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