Question Samsung TV malfunction

[Priscus]

Don't know if this is the best place to ask, but I will give it a try .....

TV is Samsung UE40EH5300K.

Looked online, and Samsung repairs will not deal with devices more than six years old. (they say because of issues with availability of parts)

This TV is a little more than six years old, but I bought this specifically to watch Blu-ray movies in my bedroom, where no aerial or network signal was available: I estimate the TV has had no more than 200 hours of use from new.

Before anyone chimes in with the usual "Buy a new TV", that I have already done, but I would still like to get this one fully functional again.

The Fault:

TV will not power up from standby. This fault came about gradually, the set becoming increasingly reluctant to power up, although once it does, it works perfectly.

This appears to be a common fault with Samsung TVs, and numerous examples found online suggest that the solution is to blow hot air from a hairdryer through the casing!

And, YES! This does work.

But is not a solution, Have to spend about ten minutes hair drying the telly every time that I want to switch it on!🙁

This TV meets my needs better than current models, so I am keen to get it fixed. As it works perfectly once hair-dryered, I guess that whatever the cause of the problem is, it is likely rather trivial. Professional TV repairers seem to incline to "we only change boards, and it is usually cheaper to replace the TV!"

There are a number of suggestions that a bad electrolytic capacitor, in power supply, is cause of these problems, and that older Samsungs are renown for this.

Looks like my only option is DIY repair. I have many times past, replaced faulty electrolytic caps on circuit boards. However, the last time I opened up a TV to look for bad caps, I could not find any evidence of such.

I have meters and oscilloscope, and am fairly proficient in use of these, but have no background in repairing TVs as such.

The Question:

Can anyone tell me, or refer me to a suitable source of info, on how to systematically find the fault on the power board of this TV?

 

[Priscus]

PS Also, I am aware that solder 'dry joints' or cracks in PCB solder can produce this phenomena.

But if they are not visibly evident, I still need help to systematically diagnose the point of failure of the TV's power board.

 

[Priscus]

Traced the problem to a 1200 microfarad electrolytic capacitor on the power board.

Some encrustation on end of this device, although it is very very slight. Still, isolating everything but this from the heat applied by hairdryer confirms that warming this component allows boot up.

All other electrolytics on power board are 25V rating, but this one is only 10V. Wonder if that is why it has failed. I guess they wanted the smaller physical size offered by the 10V rated device.

Have found replacement that will fit, and is 16 V rated, so that is what I will substitute for the putative faulty component.

Will get Christmas behind me before tackling further, but hopefully have the solution.

TV cost £400+
Used second hand, rarely found but £100 - £200 asking price.
Found a used power board on eBay, but £70 plus postage, and no guarantee it is OK.

Replacement Capacitor: mere pence!

This TV too old to benefit from the 'Right to repair' legislation, but if repairers only going to change boards, and the boards, when available, cost more than TV is worth, there must be an awful lot of junked equipment that only needed pennies to repair!