Question about TruTech PM1919BXA1 19 in. LCD TV

2 Answers

The back light turns on for about 1min and then turns off i allready replaced the dm and power board what could it be

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  • mailfast9371 Apr 24, 2010

    the tv does not turn off just the backlight after aount 1 min just woundering what it could be thanks and grate ancer

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2 Answers

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  • Master
  • 416 Answers

This is usually a power board or a ballast (also called the inverter). You eliminated the power board so the only remaining cause is the ballast. In most cases, this part is supplied with the LCD panel only. However, you should remove it from TV and inspect each transformer visually. Many ballasts that act in this manner have a failing transformer. You may be able to cross reference the part to find a suitable replacement part. I hope this was helpful, best wishes.

Posted on Apr 24, 2010

  • Adam Halfhill
    Adam Halfhill Apr 25, 2010

    Yes, the ballast (inverter) powers the CCFL backlighting tubes. When it sends itself into protection, the lamps turn off.

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  • TruTech Master
  • 12,061 Answers

Http://www.fixdevice.com/smanuals/file/34662.html
OK above is a generic version Service and repair manual. This is what you really need to troubleshoot and repair.
Hi, well I applaud you for wanting to have a go and try to repair you set. But PLEASE, start in the right place, Which, indeed it looks like you have, as you have already replaced the PSU, so in my mind, you are off to a good start, And as you see, you MUST start, in the right place, The power supply, FIRST, as, if, that isn't right, nothing else can be. But you simply cannot do anything without a Service Manual. In this it has everything one needs to repair the set. So, OK if it is shutting down, You need to find out "Why" it is "Shutting Down" usually, it will be an "Over Current" thing, something, is drawing too much current, and the supply senses that, and shuts down, look for something, either partially or fully shorted, if it happens after an amount of time, of working and then faulting, then it is most definitely, anyway, a "Thermal" problem, the way we "Find" problems such as this is "Freeze Spray" you use this on each component that is suspected of being the "Culprit", in the area around your drive, and you will soon,find that errant component. Now, also not every fault is a Capacitor, I see many, many people that think, that Capacitors are always the "Culprit" and replace them, because someone else had done so and it worked, Well that maybe sometimes true, Any Low Value higher voltage Electrolytics, should be replaced, "on Spec" (As soon as you see them) as we say, but most Symptoms, can, and do have many, many different "Causes" & also, now while that may be true in a few cases, a faulty Electrolytic Cap, or even, ordinary, Cap goes faulty, this is only a SYMPTOM, something has damaged those caps causing them to "Fail". One MUST always find the root "Cause", otherwise if you just treat, the SYMPTOM, the "Cause" will just make the "Symptom" come back, in short order, as the prime cause still, hasn't been fixed., usually either the PSU, has problems, or, bad circuitry, on the affected "Rail" to the Components affected. Now Capacitors hate AC ripple, or Over Voltage. Thats it. Oh.. and Heat, if these Capacitors, are too close to a Heat Source, then thats a prime cause of failure. Resistors, hardly ever go faulty,and if they do, it is generally obvious. However it doesn't hurt to check values with our Multimeter. Remember though resistors are made, with up to 20% tolerance from stated value, as such, are not too critical, unless in Timing circuits etc. Always check, the Values, of resistors, as with any other component, with the power OFF. Now Diodes especially "Zener Diode", are another thing to check, those and ordinary "Signal Diode" should always be suspect. next we have Transistors and IC's. The Transistors MUST ALL be checked to see if they have a good, "Junction" this is done, with our meter set to "Diode Test" and usually are about 0.6 to 0.7. With IC's you must check, voltage levels, or Logic Levels, going in and out, have a look at the circuit diagram, and it will tell you what they should be. It is a good idea to always measure the Power Supply voltages, see if a "Rail" is Low, that will be because some component has gone somewhat or all short circuit, to Earth, now, if the "Rail" is Higher, suspect an "Open Circuit" component, like a Diode, or Transistor. The voltages expressed in the manual are spot on, ANY variation MUST be investigated. I have been doing all this for over 30 years now, and I do indeed wish, we could have a set of "Symptoms" and be ables to say.. "Oh that;s the so-in-so and replace this" however unfortunately this although does happen, most "Symptoms" can have literally tens, of "Causes" all often "Interlinked" One simply has to do a methodical troubleshooting procedure, and always think, "are my Voltages Correct" as this is how, you Fix the problem, by making them so. Keep up the good work. If that link above doesn't furnish a Service manual, it is imperative you get one, even if you must pay for it. It will pay for itself in about 2 mins.

Posted on Apr 24, 2010

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Posted on Jan 02, 2017

robotek
  • 1512 Answers

SOURCE: the back light turns on

Hi there,
Just wondering if they were new or second hand boards you used. I would be inspecting the inverter circuit for the back-light is causing the problem for you. Short of replacing that also,I would be looking at repairing the area itself. If you have some electronics experience and the tools required...common problems you may find are

  • dry solder joints about inductors, power transistors and components that run hot. The heating and cooling associated with running then turning off produces dry solder joints over time.
  • replace electrolytic capacitors in the inverter stage. They can also over time dry up and their effectiveness be reduced.
The fact that it operates for 1 min makes sound like a heat related problem. There are methods of determining problem areas using freeze spray to cool individual components to determine if they are the offending part. Be careful to avoid moisture build up condensed from the air when using this method. Gentle prodding of the individual parts and spots on the PCB with a plastic tool can also help to locate any dry solder joints. Hard to tell you exactly where to look, but with perseverance, you may get to the bottom of it.
regards robotek

Posted on Apr 24, 2010

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1 Answer

TV won't turn on, red light flashes on TV and hear a clicking sound in back of unit is it worth fixing?


Yes,the LED power lite on the front panel stable?Yes,mean the DM power supply board is good.LED power like blinking,mean the DM power supply board is dead.DM power supply is good,still making that clicking sound,when turn on.Mean ur Blast board is dead,that the board that help to light up the projection lamp.

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1 Answer

The back light turns on for about 1min and then turns off i allready replaced the dm and power board what could it be


Hi there,
Just wondering if they were new or second hand boards you used. I would be inspecting the inverter circuit for the back-light is causing the problem for you. Short of replacing that also,I would be looking at repairing the area itself. If you have some electronics experience and the tools required...common problems you may find are
  • dry solder joints about inductors, power transistors and components that run hot. The heating and cooling associated with running then turning off produces dry solder joints over time.
  • replace electrolytic capacitors in the inverter stage. They can also over time dry up and their effectiveness be reduced.
The fact that it operates for 1 min makes sound like a heat related problem. There are methods of determining problem areas using freeze spray to cool individual components to determine if they are the offending part. Be careful to avoid moisture build up condensed from the air when using this method. Gentle prodding of the individual parts and spots on the PCB with a plastic tool can also help to locate any dry solder joints. Hard to tell you exactly where to look, but with perseverance, you may get to the bottom of it.
regards robotek

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1 Answer

Wont turn on the green light in front keeps blinking


Replace the dm poer board . its inside the metal box on the left (looking at the back with the back removed). p/n 935C986002
Or if you can solder then replace the 7 electrolytic capacitors on the DM power board. value 1000uf16v

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2 Answers

I turned on the TV but just got a black screen but could hear audio just fine. Turned the set off and unplugged it. When I plugged it back in the green timer light started flashing and would not stop...


Nonstop blinking is likely a DM or format board - format board most likely. I have rebuilt several of these by simply replacing all the caps, about 70 of them, and takes about two hours start to finish... But this set does need to boot. It takes about 70 seconds of flashing green light before you're able to press the power button - even when everthing is working as it should..
Hope this helps!

Bill

William Rayburn, CET
Premium Technologies
PO Box 442
Long Beach, WA. 98631
360-642-4993

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1 Answer

Mitsubishi WD62525 Dead NO Power-Won't turn on


Don't think dm board will solve your issue, might want to check power board for buldging caps.

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1 Answer

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Replace the dm power board . Its inside the metal box on the left (looking at the back with the back removed). p/n 935C986002
Or if you can solder then replace the 7 electrolytic capacitors on the DM power board. value 1000uf16volt.

Jul 25, 2009 | Mitsubishi WS-65869 65" Rear Projection...

2 Answers

The Mitsubishi Ws-55711 will not turn on.


Replace the dm power board . its inside the metal box on the left (looking at the back with the back removed). p/n 935C986002
Or if you can solder then replace the 7 electrolytic capacitors on the DM power board. value 1000uf16v

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1 Answer

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1 Answer

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Good day,

mohiuddin;

If the indicator stays on then you may have an DM PCB problem and to correct this do the the folowing:

SYMPTOM: Power LED does not stop blinking after plug in.

CURE: replace C9B01, C9B02,C9B10, and C9B11 (1000 uFD 16V) on the DM PCB. Replace them with part # 181P734030 (680uFd 16V).

The DM Board (PCB) is located on the very left side of the TV looking from back. Caution on removing Board and note what cables you disconnect to access the Metal Shielded Board.
Good Luck, big IRISH.

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