Sony 70" 70X690E - It's now a divorce risk! (6 Months on kitchen table.) New power board installed! STILL trouble!?!?

[phuzzyday]

For masochists who want to see some of the crap that I have been through already... (Truly optional now though, all those trees were barked up for no reason.)

https://www.badcaps.net/forum/troubl...klight-circuit

I started a new thread to get a fresher look at things, even with eyes that looked before. It's different now!

So I got this on Facebook for $66US, blank screen. Just reseated all connectors. Perfect. For 2 weeks.

Then it died, with the 6 blink backlight circuit error. (There are Two very brief, very faint flickers on the array while it tries to power up. Only visible through holes in back.)

This is where I would have put all the info about the work I did on the power board, but it's not irrelevant. I just replaced the power board, and it's behaving EXACTLY as before. It's been on the kitchen table about 6 months. I am still married.

I have a backlight tester. It flashes the panel without trouble, around 300v.

I 'made' a test LED array with a forward voltage of about 230V, (2 'Old Fashioned' LED array bulbs that connect straight to AC, connected together. The Backlight tester shows them at about 270 and they light up.) I connected them to the new power board. Only a couple slight brief flickers when trying to power up, just like the backlight circuit.

So I THINK I can assume the backlight is ok! I also THINK at this point that the power board is ok! The replacement one is in there still, but they behave exactly the same.

I have the ability to scope anything if suggested. Any further troubleshooting steps would be GREATLY appreciated!!!

Phil D

[truclacicr]

Does the Fault pin of the IC remain low (latch) after the fault occurs?

[nomoresonys]

A brief post before the bad guy starts insulting me, It could be that pesky emmc chip on mainboard. The problem with buying used mainboards from anywhere is the seller usually doesn't verify the health of the emmc so it's a crapshoot and not worth the high prices they want. If I was hell bent on fixing a sony with similar problems which is like what I had in the past. I would send the mainboard off to Nick's or similar for diagnosis and fixing if not extremely costly. In my case it would have been great to at least know if the mainboard was ok, which can be very hard to tell without all the tools and knowledge of testing that's required.

[nomoresonys]

Some use a Ufi box for emmc diagnosing and programming but they cost a few hundred bucks. Some of the warriors here prolly have less expensive solutions. I haven't taken a deep dive on the subject.

[Storyteller12]

These Sony TVs are real finicky with the backlights.
I'm betting the backlights are still bad. The LED tester doesn't run them at full brightness to truly test them.

[phuzzyday]

NoMoreSonys - you are thinking of the mainboard. Not Power borad. Different ones here.
Storyteller - After talking to the guy who I bought the Power board from, I think you may be right! He had one. 65". It started kicking out randomly. it was a corroded connection between those stupid strips. He could get it to test, but there was enough resistance in one joint to mess things up when trying to push current. He soldered all the test points together. I like his style!

Gonna try that now! Been hoping to avoid it!

[nomoresonys]

Maybe I got my threads mixed up, I thought you said it worked fine for a while then just stopped working. A very knowledgeable member William67 I believe it was, enlightened me that a bad emmc can present in several different ways.

[nomoresonys]

These Sony TVs are real finicky with the backlights.
I'm betting the backlights are still bad. The LED tester doesn't run them at full brightness to truly test them.

Agree, also very possible.