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Dimmu TV
Dimmu TV, Handyman/Handywoman
Category: TV
Satisfied Customers: 18398
Experience:  3 years experience
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Philips 52pfl5704d/f7 LCD TV. Turns on and screen is slightly backlit,

Customer Question

Philips 52pfl5704d/f7 LCD TV. Turns on and screen is slightly backlit, but no actual display is present. "Philips" splash screen does not come up. No audio present. Removed back panel and measured 18V on all 24V pins that supply power to inverters. Does this mean power supply board is bad or should I test further before throwing parts at this TV?
Submitted: 1 year ago.
Category: TV
Expert:  Dimmu TV replied 1 year ago.
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Hello my name is***** look forward to assisting and am very sorry to hear that you are having this problem. I want to warn you that it is possible you will need to replace a part in order to fix this. There are a few different things that can cause this and a couple different parts so we would need to troubleshoot to find out for sure. Does it beep or does the LED flash in a pattern?
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Customer: replied 1 year ago.
No beeping, no flashing LED pattern. The LED on the front panel illuminates when powered on, along with the LED on the board that has all the input jacks on it (mainboard?)
Expert:  Dimmu TV replied 1 year ago.
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Yes that would be the main board, have you already looked for burnt/blown caps? The main board itself sounds like the most likely cause from what you are describing not the power supply.
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Customer: replied 1 year ago.
Just verifying that the mainboard could potentially cause the output voltage from the power supply board (the one with the two large black capacitors) to drop to 18V instead of the rated 24V. Did not see any visibly blown or melted capacitors on the power supply board.
Expert:  Dimmu TV replied 1 year ago.
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Sort of, the low voltage can mean both the output as well as the input is shorted so it can be caused by either. The fact you aren't even seeing a logo on the screen and no beeps/led codes makes it more likely to be the main board in my opinion. With a bad power supply board you should normally have at least a blinking led code.
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Customer: replied 1 year ago.
Would a bad T-Con board also typically result in beeps or a blinking LED code? You have most definitely been helpful so far; I just do not want to start throwing parts at this thing without ruling stuff out
Expert:  Dimmu TV replied 1 year ago.
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Everything should have an LED code. The codes however are stored and sent via the main board. So while possible for it to be something else it is much more likely to be the main board because of this. If you are worried (understandable) a lot of sellers on sites like eBay will let you return parts if they do not fix the problem just contact them first. You also may want to note it is possible for more than one board to be the issue, we can only find out by switching out the most likely. If this did not work, please come back and let me know what happened when you tried it by clicking on reply to expert so we can continue. If it did work, please don’t forget to leave a positive rating - it is greatly appreciated.
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Customer: replied 1 year ago.
New mainboard is in, all connections are good. Press power button, power LED on front panel lights up, LED on mainboard lights up, lamps come on and make screen a grayish color, then black, then gray again, and once more to black. No Philips splash displayed. No LED codes. Any suggestions as to what I can check next?
Expert:  Dimmu TV replied 1 year ago.
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After this happens do the lights on the front stay on?
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Customer: replied 1 year ago.
The white LED on the front panel stays on. Looking through the holes in the back of the TV, I can see that the lamps are on, but the screen is entirely black
Expert:  Dimmu TV replied 1 year ago.
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That is very odd, do you know how to test capacitors? That would be the best way to narrow it down now.
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Customer: replied 1 year ago.
Capacitors tested ok but I swapped in an available known-good PSU board. Problem persists. Any way to properly test the T-CON board? I'm assuming that would be my next step, and then the master/slave boards?
Expert:  Dimmu TV replied 1 year ago.
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You tested the caps on the main board as well? T-con failures would normally display as shift and distortions rather than completely blank. As an example this would be a sign of a t-con issue:
http://3.bp.blogspot.com/-QlXzNc10Sdc/UchFbzhH7aI/AAAAAAAAz08/LIowMVEZkIg/s1600/tcon8.jpg
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Customer: replied 1 year ago.
I have tested with two known good mainboards and PSU boards. No change in symptoms
Expert:  Dimmu TV replied 1 year ago.
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Thank you for clarifying that, we would indeed want to test the T-Con board next then if both of those are ruled out. You would want to test the caps on it the same way, specifically the 2200uf caps on the board. Philips tend to have bad quality caps so when something like this happens it is almost always due to one or more bad caps.
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