sony kdl-22ex320 fuse blows after 10 mins

[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.

[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

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

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

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.

[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

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

[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.

[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

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.

[KountZERO]

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

Please upload the service manual so I can easily see what is going on.
Never mind, I found the service manual, no schematic of course.

You beat me to it, thanks dude.
.

[KountZERO]

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

That's right, although I have not run through them on the millivolt range. All the pins that registered 12, 5 and 3.3v when it was operating showed no significant charge. I did notice however that the 12v lines seemed to creep up to 12.8/9 when working after a while which seems odd. Perhaps this is a symptom worth chasing?

[budm]

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

Further to the last post, when working the readings match those of the attached schematic. They read zero when it fails.

So there is NO (0 Volt) DC Voltages on any one of those pins of the power supply when it is not working, correct?

[budm]

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

Please upload the service manual so I can easily see what is going on.
Never mind, I found the service manual, no schematic of course.

[KountZERO]

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

Further to the last post, when working the readings match those of the attached schematic. They read zero when it fails.

[KountZERO]

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

No standby voltage at pin 10 on the connector when the shut down happens. Seems to occur faster when there is More residual charge in the caps. Fully discharged, the TV can stay on for nearly an hour, just turning off for a few minutes results in a shut down just after the snow of analogue appears.

Few pics of the reverse side attached.

[KountZERO]

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

FB = Ferrite Bead which is installed on the leg of resistor R301 to form a very small inductor on that resistor leg.

Ahha ithought it was one of these, bad eyes.

https://www.jaycar.co.uk/192oc-thermal-fuse/p/ST3810

[budm]

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

FB = Ferrite Bead which is installed on the leg of resistor R301 to form a very small inductor on that resistor leg.

[KountZERO]

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

Is there not one next to the main transformer, to the left in the 1st pic? FB303

Sorry, been a couple of years since i got the test gear out so im out of practice. Ill put some high res pics on as soon as i sort the lighting out. Was too dark just now for close ups and too much glare with the flash.

[KountZERO]

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

Test pics