Cobolt C17P0110/Gold Alliance Electronics PDV118 excessively bright
Yesterday, I bought a Cobolt C17P0110 portable DVD player (a rebadge of a Gold Alliance Electronics PDV118) with a problem with the screen.
The problem is that the screen is excessively bright, and when viewed at the right angle, you can see some of the picture.
I checked the backlight inverter section (which I have suspected) and it was OK.
S-Video inputs to the LCD (CON3 on logic board) were checked and were OK.
The -17V rail on CON6 on the logic board was twice its voltage, with the +17V rail having a very low voltage
.
It was traced back to the DC/DC converter, marked PHPI (a search found it was a TPS61041DBV).
Checking the diodes connected to the TPS61041DBV revealed that D6, used for the +17V rail was faulty and was replaced with an 1N4148.
This has fixed the problem completely, and the +17V and -17V LCD bias rails were now within tolerance
.
When D6 was faulty, the DC/DC converter had to increase its output because of the low output from rectifier D6 (which was the only rail monitored by the DC/DC converter), to a certain point.
The problem is that the screen is excessively bright, and when viewed at the right angle, you can see some of the picture.
I checked the backlight inverter section (which I have suspected) and it was OK.
S-Video inputs to the LCD (CON3 on logic board) were checked and were OK.
The -17V rail on CON6 on the logic board was twice its voltage, with the +17V rail having a very low voltage
.It was traced back to the DC/DC converter, marked PHPI (a search found it was a TPS61041DBV).
Checking the diodes connected to the TPS61041DBV revealed that D6, used for the +17V rail was faulty and was replaced with an 1N4148.
This has fixed the problem completely, and the +17V and -17V LCD bias rails were now within tolerance
.When D6 was faulty, the DC/DC converter had to increase its output because of the low output from rectifier D6 (which was the only rail monitored by the DC/DC converter), to a certain point.
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