Humax Humax 32IS51 or LCD ITT32-4000 HDS 2 yellow led / will not start

[Foppel]

Dear BadCaps Members,

i try to repair a Humax 32IS51 32" lcd flat screen with integrated DVB-S2 tuner. The TV will not turn on and the status led just glow yellow/amber. Somebody in the other Forums mentioned that the data communication between the ic's on the mainboard is interrupted. The power supply seems to be in a good condition. Somebody resolder the pins at the IC U661 PCF8563T and then it works again. Another forum member change the supercap 5.5V 0.22F. Yesterday i cooled down my mainboard and then everything works well. Then i used my fingers to warm up the caps near the pin socket on the mainboard led glow yellow/amber . I ordered the caps now and hope it will work after change. I have a ESR Meter and will test the caps and will post the output here.



http://monitor.espec.ws/section31/topic207889.html
http://forum.electronicwerkstatt.de/...173f5_bs0.html

best regards - Foppel

[Foppel]

Re: Humax Humax 32IS51 or LCD ITT32-4000 HDS 2 yellow led / will not start

I desoldered the caps and then i start to measure the capacitance. It's really strange. The temperature change the capacitance and ESR.

Samyoung: 470uF, 25V

At 20°: 514 uF
ESR: 0.04 Ohm

At 5°: 502 uF
ESR: 0.08 Ohm

cheers - Foppel

[budm]

Re: Humax Humax 32IS51 or LCD ITT32-4000 HDS 2 yellow led / will not start

ESR goes down as you heat up the cap, and goes up as you cool down the cap.
For example: this backlights inverter board only works when I heat up the caps using hair dryer (it is a good tool for troubleshooting), as you can see, at room temparature, the ESR is more than 10 Ohms, when I heat up, it went down to less than one Ohm, the capacitace is within 20%.

http://s807.photobucket.com/albums/y...t=DSC00001.jpg

http://s807.photobucket.com/albums/y...t=DSC00003.jpg

[Foppel]

Re: Humax Humax 32IS51 or LCD ITT32-4000 HDS 2 yellow led / will not start

Hi Budm,

thanks for your reply. I replaced the following caps:

10 x 470uF 16V
3 x 770uF 25V
1 x 220uF 16V

And now the TV works very well But when i use a hair dryer and heating-up the board, then the TV turns off automatically after a few minutes. So i think it is always a good idea to change all caps. Because they are all from SamWha I think they are all temperature sensitive.

cheers - Foppel