Daytek DT-3220 power problem
I have just fixed the power problem on my Daytek 3220. It looks like the Bentek BP-200AD power supply is used in other cheap brand TV's besides this Daytek : Hyundai HLT 3280, Jwin JV-DTV3212.
At first, my TV would just lose the backlight, while the video and sound would still work fine. Power cycling the tv would correct the issue, but would repeat the problem after shorter periods of time.
More recently, I've started losing the video and audio, shortly after backlight.
I have checked all the caps on the outputs and they all tested ok, using capacity and ESR meter (surprisingly enough) and no bulging either.
This power supply outputs 3 voltages : 5V, 12V and 24V, with a stand-by control pin on the 5V connector (0V for TV on and 5v for tv off).
I have got the readings after the power died:
5v out= 5v--ok
12vout=0.72v not ok
24vout=0.0v not ok
One of the transformers was squealing quite annoying while tv worked, but started modulating the squeal a couple of seconds before power died.
The culprit : one small electrolytic capacitor marked C19 on both sides of the board, with a value of 47uF/35v. I have replaced it a 56uF/50v and the TV started working as new (and of course no more squealing either).
Use a good quality cap when replacing C19. A 50v rated one would be a better choice than the original 35v and make sure it is also rated for 105 degrees Celsius, since it is very close to one of the heatsinks.
As always the DISCLAIMER: take all the precautions to avoid electrocution. Disconnect the TV from power, allow a few minutes for the big 400Volt capacitors to discharge completely, before handling and working on the power supply.
Feb 13, 2010 |
Televison & Video