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50" LED Power Cycle Problem

Note: My TV is an Emerson, but it was manufactured by Funai. The EXACT same TV is sold as a Philips Magnavox.

I have an Emerson TV, Model No. LF501EM5F, Serial No. DS1A1422155472 (A3AUQUH). According to the label plate, the TV was manufactured by Funai. The TV has had a problem for between 9 and 12 months. The problem may have gotten slightly worse in the past few months, but not much worse. It has been a fairly consistent issue.

Here is the issue: When I attempt to power the TV on, the TV may turn on, however, more than likely, it will not turn on. It will usually take 5 to 20 attempts to get the TV to come on. Here is what happens. Before I attempt to turn the TV on, everything is as it should be. The standby light in the bottom, middle of the TV is steadily illuminated.

When you hit the power button on the remote OR the power switch in the rear of the TV, here is what IS SUPPOSED TO HAPPEN. The red standby light should go off as soon as you power the TV on (either way, by remote control or rear button). After about 2 seconds, the standby light should start to blink and the TV backlight should turn on. After another 2 to 3 seconds, the TV full picture should come on and the red standby light goes off. You are now watching TV.

Here is what happens when I hit the TV power button on the remote control OR hit the physical power switch  on the back of the TV (the problem is the same regardless of whether I use the remote control or push the TV’s rear power button). The TV MAY start as it is supposed to. I’d say that happens 10-15% of the time.

85% of the time, this happens: The red standby light goes off when the TV’s physical power button is pushed or the remote control’s power button is pushed. From there, the red stand by light will blink occasionally, but the TV never comes on. Eventually, the red standby light comes back on. Once that happens, I can push the power button again for another try. There is no consistency in the cycle time from when I initially push the power button until when the standby light re-illuminates solid allowing me another attempt. The cycle time for that process to play out is sometimes as short as 10 seconds, but it can also be 3 minutes before the standby light comes back on. Likewise, the number of times the standby light flashes during this cycle varies greatly. It may flash 2 or 3 times. It may flash more than 10 times. After a varying number of attempts, the TV eventually always turns on, but it sometimes takes 15 or 20 minutes.

I have done some searching and this seems to be a fairly common problem for this TV. The problem is; sometimes the problem has been fixed by replacing the entire power board, sometimes the problem has been fixed by replacing the entire main board and sometimes the problem has been fixed by replacing just the main board EEPROM.

I know this is a low quality TV, but I am currently strapped for cash and can’t afford to buy a new one for a few months. I am therefore looking to fix this one as cheaply as possible. Can someone give me some help diagnosing the specific problem. I have an excellent multimeter and am well versed in its use. I also have quite a bit of soldering experience, although its probably been a couple years since I did any micro-soldering of really small PC board components.

I am trying to avoid replacing one component as a guess on how to fix the TV and then replacing a 2nd, 3rd, etc. component if the problem doesn’t get fixed. CAN ANYONE HELP ME SPECIFICALLY DIAGNOSE THE ISSUE SO I REPLACE THE RIGHT COMPONENT THE FIRST TIME? EEPROM is roughly $15, power board is about $50 and main board is about $75.

Can anyone help?

Thank You,

Bill Granger

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Fix Kits pour Android

Remplacer l'écran ou la batterie est à portée de kit !

Acheter maintenant

Fix Kits pour Android

Remplacer l'écran ou la batterie est à portée de kit !

Acheter maintenant

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Pull the power board and replace all the electrolytic capacitors 20uF and above. Switched mode main power section isn’t reliably starting up. I’ve had this fix all (10+) but one. It’s so common there are sites selling kits by make & model.

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@wjgrange you will need to check the DCV at the following jumpers once the power switch is activated:

J239: P-ON-H2

J209: RESET

J211: LED-cont

J257: BL-SW

J258: PROTECT3

J249: BL-ADJ

Let us know what you find. We will also need to see your boards, most importantly your power board. Post some good pictures with your question. Ajout d'images à une question existante Yes, you can get a kit that has the most commonly failed components. Those are

Diode D604

Diode D605

Diode D607

Diode D609

Diode D610

Diode D640

Resistor R602

Resistor R605

Resistor R606

Resistor R608

Resistor R611

Capacitor C220

Capacitor C637

Capacitor C631

Capacitor C632

Capacitor C648a

Capacitor C649a

Voltage Detect IC601

Transistor Q600

Mosfet Q601

Fuse F601

so check around those parts for any failure. We’ll need the schematic to determine the values of the components.

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Bill Granger sera éternellement reconnaissant.
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