My TV keeps turning itself off!

Wild1 · Senior Member

RE: My TV keeps turning itself off!

VKPORTABLE · Senior Member

Wild1 wrote:
Hi Peter, its on 240 via the inverter, its not a 12 volt tv.
Jennifer

Before dumping the tv, I would be looking at the Inverter you are running.

Is the Inverter up to the job? On the back of the tv you should see it's power consumption in watts, same for the dvd player if it is separate. Add these up, and anything else you are running from the Inverter at the time and ensure your not exceeding the inverters capacity of supply.

Another thing to check is the inverter itself, is it a raw inverter, modified sine-wave or pure sine-wave version.
Some electronic devices will present with odd behaviour on anything but a sine-wave supply.

Mark · Senior Member

dorian wrote:
johnno02 wrote:
As an Ex TV Tech,one of the things we used to do was give it a gentle/sharp Tap,(Not Too hard)
on top of the Set ...
There's actually a technical term for that:
http://en.wikipedia.org/wiki/Percussive_maintenance

Does that actually lead us to the actual problem??
Just interested to know, you tap it, it works, what was wrong?? Hardly a "technical" repair solution in my opinion.

DeBe · Guru

AU BEM 3.JPG AU BEM 4.JPG

Well yes Mark, taping a unit can temporarily fix a item if a dry joint is involved. Pictures of an AU ford falcon BEM module. Fault is usualy wont crank, hit dashboard near left knee in drivers position. Car now cranks, fault is dry solder joints on relay on the circuit board. Just resolder & its fixed. Have repaired many ED/EL/EF/AU Falcon Body Electronics Modules. In the picture the dry joints on the relay pins are there to see, marked with a black texta dot. Dry solder joints are quite common in electronics.

Wild1 · Senior Member

Boy, did I get my money's worth outa you lot! Thanks John, Mark, QueenKombi, Johnno, DeBe, Dorian and that other fella/lady for your thoughtful input. I'm now gonna give it a sharp rap over the head, pull it apart, get the manual, buy a new TV and chuck it away.

But seriously I don't fancy pulling it apart - I've heard some TV components can be very dangerous. I've already sourced a TCL 24 inch for $237, it has all the bells and whistles including time shift (which sounds intriguing) but now DVD player, DVD's are almost obsolete now anyway. It can record from the EPG and play via a USB. Now all I need is a cheap antenna and I'm set.

Jennifer

dorian · Guru

Mark wrote:
dorian wrote:
johnno02 wrote:
As an Ex TV Tech,one of the things we used to do was give it a gentle/sharp Tap,(Not Too hard)
on top of the Set ...
There's actually a technical term for that:
http://en.wikipedia.org/wiki/Percussive_maintenance
Does that actually lead us to the actual problem??
Just interested to know, you tap it, it works, what was wrong?? Hardly a "technical" repair solution in my opinion.

It's not a solution, but it's a diagnostic tool.

As technicians, whenever we had to troubleshoot a device with an intermittent fault, we would "tap test" the boards with an insulated rod (or the handle of a screwdriver). Then we would reflow the solder joints in the affected area, even if they all looked OK. Sometimes the "dry" or "cold" solder joints were obvious, as in the AU Ford BEM example, but often they only showed up when the board was tapped or flexed or heated or frozen. To locate a suspected thermal fault, we would use a hair dryer and a can of spray freezer.

Mark · Senior Member

Thanks to DeBe and dorian for enlightening me, I'm always interted to learn new techniques.

I am still curious how this helps Wild1 resolve the issues with the TV though, and I think that's where I am confused.
If it is tapped and it works how would Wild1 determine what is wrong with it and how would jennifer fix it??
Then of course there is the cost of repair over a new TV, is it actually worth it??

Incidently the TEAC TV on/off swtich must be different to that of a momentary puch button device as you have described as I have bypassed the switches on several TV sets and they worked fine, we just turned them off on the wall (mains switch).

Thanks once again for the information, I'll keep it in mind for all the non-start cars we see. Much appreciated.

Mark

dorian · Guru

If something begins working or stops working after you tap it, then you can be reasonably confident that the device has a bad connection or a bad solder joint. It just remains for you to dismantle the device and look for it.

That said, sometimes tapping or flexing the problem device can get it to work long enough to limp home to the workshop, as in the Ford case. It's not a permanent fix, though.

To give you an example, I had a new soldering station which, ironically, had a bad solder joint on its circuit board. To fix it, I flexed the board until it came good, and waited for the iron to heat up. I then powered off the iron and used the residual heat in the tip to reflow the bad joint.

dorian · Guru

Mark wrote:
Incidently the TEAC TV on/off swtich must be different to that of a momentary puch button device as you have described as I have bypassed the switches on several TV sets and they worked fine, we just turned them off on the wall (mains switch).

I know the switches you mean. IIRC they were made by Alps and were long, horizontally mounted, plastic bodied types, usually black and white. Some had a set of momentary "reset" contacts so that the set would switch on automatically rather than powering up in standby mode.

Nowadays the TVs are always in standby mode, and there is no AC on/off switch like in the old days. ISTM that things were "greener" back then. The same thing happened to desktop computers. A decade ago they had an AC on/off switch, but nowadays it's just a momentary pushbutton, and the computer is always in standby. I can maybe see the point of standby mode for a TV that is remotely controlled from the couch, but what's the excuse for a desktop PC that is within arm's reach?

Anyway, here is an example of what you find in today's appliances:
http://i00.i.aliimg.com/wsphoto/v0/510911528/1000pcs-Tactile-font-b-Push-b-font-font-b-Button-b-font-font-b-Switch-b.jpg

Some switches have a lower profile actuator, but their function is the same.

Mark · Senior Member

Mark wrote:
Thanks to DeBe and dorian for enlightening me, I'm always interted to learn new techniques.
I am still curious how this helps Wild1 resolve the issues with the TV though, and I think that's where I am confused.
If it is tapped and it works how would Wild1 determine what is wrong with it and how would jennifer fix it??
Then of course there is the cost of repair over a new TV, is it actually worth it??

Incidently the TEAC TV on/off swtich must be different to that of a momentary puch button device as you have described as I have bypassed the switches on several TV sets and they worked fine, we just turned them off on the wall (mains switch).
Thanks once again for the information, I'll keep it in mind for all the non-start cars we see. Much appreciated.
Mark

Once again thanks for the enlightenment, it still doesn't explain how Wild1 would identify the actual problem and solve it, herself, as a layperson. (unless secretly she is an electronics engineer and then I guess she wouldn't have posted in the first instance)
I guess we could just go around in circles all day about "tapping and dry joints" but that's a debate for another subject of which there are for's and against's.
I just hope that Wild1 gets a TV sorted out.
Regards

Mark