View Full Version : Another curbside rescue...

05-25-2013, 10:16 AM
Just found a 32" Magnavox 32MF231D/37 on the curb. Really clean condition, and thrown in my truck right before it started raining.:thmbsp:

Threw it onto the bench and powered it up. Power LED comes on, and LCD backlights turn on, but no picture and no sound. Found a few bulged and vented capacitors on the SMPS board (big surprise, right?). Ordered some new caps from DigiKey, which should be here early next week.

Figured it was worth $5 in caps to try fixing it, even if I don't really need another set around here. Can always flog it on Craigslist for a few bucks.

06-04-2013, 10:11 PM
OK, so put in the 3 caps on the SMPS board, and now both outputs on the SMPS (+24 and +16) are good. Still no pix, though.

Backlight comes up, and 2 SMD leds on the main board light up steady green.
All the lower operating voltages (+12, +5, +3.3, etc.) are derived from the +16 rail via multiple DC/DC converters and regs on the main "scaler" board. What should be a +12V rail is putting out +16V.

Will try substituting an external +12 for further testing. The +12V appears to be derived from +16 by a L5973 buck regulator chip. Chip appears to be internally shorted from Vin to Vout. Will stick one in next parts order.

Couple SMD electrolytics on main board seem a little bulged or are running warm. Will replace.