LG 32LC7D No Video or Audio

[BBoles]

Hello Everyone, I am new to the site and was looking for some help with my LG LCD TV. The unit has been shutting down occasionally at first and now does not have video or audio. The power light turns green and flashing for about 15 seconds when turned on and then normal green LED indication, but there is no audio or video. I still work in the electronic field but haven't opene up a tv in about 15 years. Anyhow I am starting at the power supply and have it pulled but not sure how to check it on the bench. I have the ac power applied and the 5v+ is available on the connector points but not sure how to tell it to power up the rest of the power supplies. No 3.4v, 6.5v or 12v, I would appreciate any help.

Thanks,
BBoles

[tmwalsh]

Re: LG 32LC7D No Video or Audio

In most cases, it is almost impossible to bench check a power supply unless you provide adequate loads on the outputs. That said, most power supplies take a signal in the 5v range to enable them. Or they need one of their pins pulled to ground for a short period.
I would have tested the outputs while the supply was still mounted to the rest of the set if at all possible. And would have monitored the signal pins to determine what happened when the 'on' button was pressed, to verify that the PS was being told to start up.
If you take a look around this site, you will notice the emphasis on electrolytic capacitors. They have become a 'cottage industry' for those that can replace them. Inspect your for leaking electrolyte, tilting & separation at the base and for bulging tops. Many brands have been brought to market in the recent past, and some have developed a reputation as being food for the recycler... after short lives.
tom

[BBoles]

Re: LG 32LC7D No Video or Audio

Thanks for the response.
Work is good they been keeping very busy and long days. I am thankful.
I have performed some static checks on the components on the Power Supply and caps, diode, chokes and fuses check good no appearance of damage or cracked leaking capacitors. I reinstalled the power supply and took some voltage reading to ground pin on connectors, with the set on and off. I am going to try and attache my result see if anyone can see more than I understand. Woops not sure how to do that. I will list my findings.
P201 off on P202 off on
1-ACD 5V 4.9V 1-19V 0V 0V
2-ON\OFF 0V .6V 2-19V 0V 0V
3-ST5V 5.1V 5.1V 3-GND 0V 0V
4-GND 4-GND
5-INV/CTL 0V .7V 5-6.5V 0V .7V
6-ERR .68V .68V 6-GND 7-BURST 3.2V 3.2V 7-3.4V 0V 3.4V
8-ST5V 5.1V 5.1V 8-GND
9-GND 9-12V 0V 0V
10-A-DIM .84V .92V 10-GND
11-6v 0V .74V
12-GND
13-3.4V/ON 0V 2,4V

Thanks,
BB