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Sanyo DP37819 - shuts off    
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LGMR



Joined: 20 Dec 2015
Posts: 2
Location: Mississippi

PostPosted: Sun Dec 20, 2015 6:34 pm    Post subject: Sanyo DP37819 - shuts off Reply with quote

Hello everyone. I am trying to repair a TV for my friend, and hopefully learn some things in the process. The TV powers on and the screen lights up for a few seconds. The screen then shuts off and the speakers start making a distorted static noise.

Using a flashlight, the screen appears to still be on. It was very hard to tell since it was just a snowy screen. But the back light is definitely off. It will stay on until it's turned off, so the cpu isn't turning the whole set off, just the screen and/or backlight.

I found the service manual online, you can download it here:
http://www.electronica-pt.com/esquema/tv/sanyo-esquemas-tv/sanyo-dp37819-ch-p37819-00-25116/

I'm getting low voltage readings on several chips. Pin 48 on IC800 is reading 2.6V. On IC1670 Pin 1, the input, is giving me 14.1V and Pin 2, the output, is giving me 8.6V. And on IC 1630, Pin 1, input, is reading 2.3V, and Pins 3 and 6, outputs, are reading 1.8V each.

Q1651 is so small, I had a had time testing it, and IC1680 doesn't seem to exist, it's not on the board, and the manual never references it again.

Since I'm getting all these low readings, I'm thinking there may be something wrong with the PSU board, but I don't see any bad caps or anything like that on it. What do you guys think? Thanks for helping me out.
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JTS1957



Joined: 21 Jan 2009
Posts: 2247
Location: Far, Far Away

PostPosted: Sun Dec 20, 2015 7:23 pm    Post subject: Reply with quote

LGMR wrote:
The TV powers on and the screen lights up for a few seconds. The screen then shuts off and the speakers start making a distorted static noise.

Using a flashlight, the screen appears to still be on. It was very hard to tell since it was just a snowy screen.


Are we expecting picture & sound with NO active Inputs connected or selected?
LGMR



Joined: 20 Dec 2015
Posts: 2
Location: Mississippi

PostPosted: Sun Dec 20, 2015 7:44 pm    Post subject: Reply with quote

JTS1957 wrote:
Are we expecting picture & sound with NO active Inputs connected or selected?


No. When powered on with a source, the picture comes up for a second, then shuts off and the speakers distort. I was referring to the default input, which is the antenna input, and it's supposed to have a snowy screen if there no active source.
tvdude123



Joined: 23 Dec 2015
Posts: 1
Location: California

PostPosted: Thu Dec 24, 2015 12:04 am    Post subject: Reply with quote

Take a flashlight and point it to the TV screen after the screen turns off. If you can see an image (e.g. menu) then it is the backlight inverter.
JTS1957



Joined: 21 Jan 2009
Posts: 2247
Location: Far, Far Away

PostPosted: Thu Dec 24, 2015 12:28 am    Post subject: Reply with quote

Flashlight works exceptionally well when the set has an active A/V input selected. You'll get intelligent audio that matches the faint video. (An inactive off-channel tuner signal - snow for video, white noise for audio, wouldn't meet that definition - menu might or might not be discernible.)
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