sony kdl-22ex320 fuse blows after 10 mins

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

Still searching for a schematic. The AZ2W chassis does not bring results nor does the board ID and manufacturing code. Even tried the QR code with no result.

[petehall347]

Re: sony kdl-22ex320 fuse blows after 10 mins

use infra red to find the hot spot then freeze it to confirm . just a suggestion .. probably feel it with a finger with power removed at fault condition .

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

Had a senior moment today, there's me thinking there is no 3.3v stb when it dies, perhaps I should check the gator clip in the negative probe is actually OK before relying on the meter readings. It seems that the stb does drop out for a while but comes back fairly quickly it just doesn't seem to wake the beast.

So today I soldered the clip onto a spare banana lead and.went a-probing. To which I ended up briefly shorting the gate and drain of that solitary j649 MOSFET and cha-ching the pos turned on! So either the FET is toast or its feed circuit.

Don't really want to keep recreating the glitch but it does it everytime.

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

Do these TVs use CFLs for a backlight or led strips? Starting to think it might be the backlight causing the issue.

[vinceroger69]

Re: sony kdl-22ex320 fuse blows after 10 mins

these sets are 22in edge lit led tvs

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

OK so its not going to be an inverter failing that's causing it then. Having only ever messed with lcd, I wasn't sure how the backlight was done on an led.

Going to pull that MOSFET tomorrow and check it.

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

got hold of the service manual with schematics

Its too big to upload here so I'm going to take the relevant pages out and upload

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

Threw it up on MEGA for anyone to check out.

https://mega.nz/#!ebgnUKJb!Z8cRqXhwO...AxQiNtJWd5tnoo

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

After much agro here is the schematic, no component list for it though.

Thanks for trying to help and dealing with my abstract ramblings. Pain meds can take me on some weird mental journeys.

Current state of play is..

There is no 3.3v stb output
The 12v line comes back briefly after 240v applied then decays rapidly (because of the lack of stb switching?)
The unregulated 24v line for the backlight reads 17v then decays away.

Levels from all the windings on the low voltage side are lower than I would expect or non existent leading me to believe its the hot side going down. Going to look again at the pwm and bridge.

[KountZERO]

Re: sony kdl-22ex320 fuse blows after 10 mins

Ok, gave up on this psu as it seemed to be just getting worse.

Picked up another tv with a smashed screen for 25 quid delivered off ebay. Up and running in 10 minutes.

Thanks for trying guys.