Television Powers Off

I haven't looked up your particular set but it sounds like the protection circuitry is turning off the tv after a short time.

First and foremost, be careful as there could be high voltage inside the set even when its off. You can read up on how to discharge the flyback to be safer.

Perhaps a part is overheating and going out of range so the protection is shutting it off before it becomes more serious. For starters you might just clean the dust out of the tv and off the circuit board. I often do this with compressed air and a paint brush, although Ive used an electric leaf blower in a pinch. Sometimes just cleaning it out fixes it.

Depending on how old the set is some capacitors start failing over time. If its that hard to fix im not so sure its worth it as much of today's electronics just isn't made to be repaired easily, or feasibly.

On the other hand I have traced problems and fixed a number of TV sets which I still have today. The problems I have encountered have been all different from a bad resistor to a bad voltage regulator, but all were quite a pain to diagnose.

Good Luck

I would only add to the first post by saying that if it turns off so quickly, the fault may well lie in the power supply, and if this is a new TV to you perhaps a double check of the operating voltage and frequency might be in order... Or a power supply capacitor etc...

Otherwise as the first poster said, on today's TV's ,monitors etc... they're not designed to be easily repaired, i.e. surface mount devices and heatsinks riveted on to power components etc...

John.

I agree Domerdoc, everything these days seems to have built in obsolescence, after that time expires the only way to repair something is to buy and replace complete pcbs - if you can get and afford them.

I had a decent 17" monitor that popped its line output transistor after only 2 years of use, back in 2002, I set about repairing it but the transistor had been riveted on to the heatsink and trying to drill it off damaged the surrounding SMT components, so for the sake of a 50 pence transistor the whole thing was used as land fill...

John.

Too Right!!!

I believe I read somewhere that the CRT contains several pounds of lead!! Whether that's in the glass or what I don't know, but it certainly feels heavy enough!

For a few years it was sat on the floor as I just couldn't think of throwing it away so early in its life... But the space it took up and the lack of anyone interested in it as something to play with meant it had to go, and the only place that would take it was the local tip!!

Back in the 60 or 70s most electrical items could be repaired, today I still hunt ebay for the elusive instruments that are going to be thrown away so I can rescue them, repair and restore them back to good working condition - its my hobby! Nobody seems to realise that modern electricals are only cheap because they don't last very long, take mobile phones... have you seen any youngster with a mobile which is a few years old? Most people want the latest 'sexy' mobile and so the few years old ones are thrown away!!

John.

The television was manufactured in 2003. I have found a source online for a service manual for an MD19N1-sans the "(-P)" -but don't know if it will suffice for my purposes.

First, it it very doubtful that the -P suffix is relevant to your problem.

You say it stops in a matter of seconds. So the picture probably never appears...and CRT and related circuitry can be (provisionally) eliminated as the problem.

It must be assumed that audio is okay until the TV goes dead...just for the heck you could change channels and see if audio functions momentarily at all live channels. This eliminates audio and tuner subsystem.

So, most likely power subsystem is at fault. You did not say how long it takes, if any time at all, before the unit can be switched off and back on...to generate the same failure; or if the failure always occurs or is intermittent; or what the TV (ambient) temp is when you see the failure.

The failure mode (start momentarily then stop) suggests a heat related problem--possibly a defective junction/joint which makes contact when cold but breaks contact when heated. Heat can also cause slight flexing of a board enough to disconnect a poor joint.

A damaged power cord could also be at fault. Cords fail quite often because they are subjected to stresses or just degrade for various reasons. For example there could be a slight break in a wire under the cord insulator. Try manipulating the cord when you get the failure to see (hear) if doing so makes the set try to start again--listen for speaker output or static.

Troubleshoot by starting at the cord (which is disconnected from TV chassis) to see if it meters consistent voltage when plugged in. From there trace inward into the set looking for poor joints in the power subsystem. Sometimes even flexing the board by pushing with a non-conductor will uncover the defect. Or you might see a spark at a poor joint when the chassis is powered on. If you verify that wiring and board traces are not opening or discharging across air, you have isolated to power subsystem active components. You can then test these or come back for more advise. As said before, be cautious when opening and powering set/chassis when case has been opened. Don't let anything, or the picture tube, come in contact with your person. Work slowly and carefully. If you use a magnifying glass for inspection, and it's metal, be careful it does not contact live (or dead) circuitry.

the last poster was right on the money the very first step i take after observing the symptoms is to break out the soldering iron and re solder all the poor or cracked connections on the circuit board the lead free solder they are using now is spotty depending on a number of factors, some manufacturers it is good to ok others have ring cracks around a number of components within 1 year of manufacture. does the tag on the picture tube say orion if so get out the magnifying glass and soldering iron after fixing all the bad connections then power up and re diagnose be careful soldering not to bridge or splash any solder as this will defiantly change the symptoms..this method is the most efficient as chasing intermittent can be a real pain. in my experience 40 to 60 percent of consumer electronic failures are bad connection -solder related- most of the time power supply or horizontal section failures are ultimately due to bad connections

These days, most faults in ctv are in the smps, or the lopt, or the vert- the prof. starts by analysing symptoms( I use an inline ammeter) with a quick off switch- then measure the bridge cap- full volts?= smps ok- isolate drive to lopt- sub globe across B+- full volts & globe lights? fault in lopt circuit usually- this is how diagnosis is conducted - remove sections from circuit till B+ stabilises, then fault find comp in faulty section.

Does the Toshiba TV have a built in VCR? I had a TV with a built in VCR which the VCR section was defective. On power up, the VCR would try to eject a tape when there was no tape in the system. After a second or two of operation, the VCR motor protection circuit would kick in by turning off the VCR and the TV.

To get the TV working, I had reset the VCR section to the idle state by manually moving the VCR mechanism (with the power off).

It's a t.v./dvd combo. There is a dvd loaded in it with no known way of ejecting it! I am waiting patiently for a service manual/schematic that I ordered last week. Thanx for the idea!

Go straight to dvd pwr supply- check electros 1st with esr meter, then cap meter, then analogue mm for s/c- or just r/p the lot- the timing mech of dvd/cd often slips- r/p belt/s- retime(use trial & error till you can suss out)- to remove disc simply unscrew housing- use thought- sometimes a 6v batt applied to load motor works- resist the urge to smash the cheap junk plastic mechanism to pieces!. At least not yet- wait till laser burns out, or logic board fails!- not far away!.

upon finally receiving the $25 service manual i was able to remove the dvd unit from the circuit/television. after manually ejecting the dvd disc, which was stuck in the unit, and then reconnecting the dvd player back into the circuit, the television powered up beautifully! even though the dvd drawer opens/closes ok i have since told the daughter not to use it. will just add on an external player if she really wants to play her dvd's. great sense of accomplishment and savings of money! couldn't have done it without all your help/ideas. thanx to ALL!

Congratulations!

Let her use the DVD. The DVD might not fail again and anyway you know how to fix it.