Sanyo Model 26640 26" Flat-Panel not powering on

[vortalexfan]

Hello everyone, a couple of weeks ago a friend of mine from church asked me to see if I could get their old Sanyo Flat-Panel TV going for them, its a Sanyo Model 26640 according to the tag on the back, and its from 2011, and the problem the TV is having is that its refusing to power on.

At first I thought it might of been a capacitor issue in the power supply (this was before I saw the date of 2011 on the back) but then when I took the TV apart and looked at the power supply board I didn't see any bad capacitors (and that's when I looked at the date of manufacture and when I saw it was from 2011) so then I remembered that with my LG 3D TV that was made a year later had the same issue and it was mentioned on here that the power supply cap issue was fixed in these flat panels by this time period.

Which leads me to think that perhaps the mainboard is bad in this TV, am I on the right track here in suspecting the mainboard on this TV, or is it something completely different in this set?

Any help with this issue would be appreciated.

[MadMan]

Well I would rule out the PSU first. I'd say it's the more likely failure point. It's hard to be certain, but in general, if the main board had an issue, pushing the power button would elicit SOME reaction from the PSU, like an attempt to turn on, then quickly turning off. A dead PSU would likely have no response at all. Is there like a standby indicator light on the tv?

You could probe the PSU outputs for voltage while pressing the power button, see if anything ever comes out.

[vortalexfan]

Originally Posted by MadMan

Well I would rule out the PSU first. I'd say it's the more likely failure point. It's hard to be certain, but in general, if the main board had an issue, pushing the power button would elicit SOME reaction from the PSU, like an attempt to turn on, then quickly turning off. A dead PSU would likely have no response at all. Is there like a standby indicator light on the tv?

You could probe the PSU outputs for voltage while pressing the power button, see if anything ever comes out.

The TV does have an LED light but it doesn't light unless you hit the power button, which when you hit the power button the light glows red for about 3 seconds, showing that the TV is trying to power on, but then it just shuts down and the LED goes back off.

I did take a look at the Power Supply board on this TV but didn't see anything obvious that looked like it had failed (no bulging electrolytic caps, no blown fuses, no burnt traces, etc.)

So I'm not sure what's going on with this TV.

[MadMan]

Well I'm no expert. But I will say that I've had dozens of computer psu's take a dump with no noticeable damage.

[vortalexfan]

Originally Posted by MadMan

Well I'm no expert. But I will say that I've had dozens of computer psu's take a dump with no noticeable damage.

So have I but I know that from past experience with working on power supplies on Flat Panel TVs when they failed it was usually obvious when they failed. But I know sometimes electrolytic caps can sometimes fail and still look normal (they haven't vented).

I guess I'll go back in with my ESR meter and check the capacitors in the power supply and also the voltage regulators and diodes to see if any of those have failed.