How to Troubleshooting and Repairing the "No
Signal" Error Message in the LCD TV
Model : Hisense TLM55V88GP LCD
Symptom : "No Signal" Error Message
show on the screen when using VGA signal input.
When testing this LCD TV, all other input were found to be good except the VGA
input. When plug in the VGA connector to this LCD TV from desktop computer or even laptop the result were the
same- “NO SIGNAL” error message shown on the screen.
This LCD TV was used in the shopping mall
for displaying content purpose. Since it is a
display set in a shopping mall, the customers and the staff always plug and unplug the VGA connector without
turning the power off causing the above error to appear. Others input of this LCD TV was not affected except the
The troubleshooting will be on the VGA input
circuit and below is the VGA input signal diagram.
R, G and B lines open circuit will not cause the above symptom except if there
is component shorted. If the HS or VS line (VGA connector pin 13 & 14) have an open circuit the above
symptom will appear because no signal from the CPU could pass through. In this LCD TV, I found a resistor (R103-100ohm) that is located
in series with the HS line had an open circuit. The problem now was that the error message did not go away
even the SMD resistor (R103) was replaced.
I continued to check on the components that is corresponding to the R, G and B
line (pin 1, 2 and 3 of the VGA connector) and found Z7, Z8 and Z9 were shorted. Those SMD resistors R98, R99
& R100 (all 75 ohm) that is connected from the R,G and B line to ground were open circuit
Components located in the pin 11, 12, 15 (VGA-SDA, DDC-SDA & DDC-SCL) were
found to be good. This LCD TV was brought back to life again after the components were
Below is the picture where the defective components were
Conclusion-Hope you have enjoyed the article and remember to check all components in
any input if you found that the particular input is not working be it a VGA input, HDMI and etc.
To your success!
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