Re: LF501EM5F No Power, Chirping/Beeping Transformer
i get 161vdc with the negative lead of my DMM on the negative terminal of the big cap and the positive lead on the jumper marked "PFC_VOUT".
pillit83
Member
Last Activity: 08-19-2016, 11:59 AM
Joined: 09-09-2014
Location: Pitman, NJ
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Re: LF501EM5F No Power, Chirping/Beeping Transformer
Going off the labels you pointed out, I have:
(power supply plugged in, nothing connected to it)
amp +13v -> reads 8.18vdc
p-on +21v -> reads 13.53vdc
p-on_H2 -> reads 0.00vdc
all +3.3v -> reads 0.00vdc
bl-sw -> reads 0.00vdc
(power supply plugged in, main board connected to it, transformer beeping)
amp +13v -> fluctuating 3.8vdc~4.1vdc
p-on +21v -> fluctuating 0.00~1.2vdc between beeps
p-on_H2 -> reads 0.00
all +3.3v ->...Leave a comment:
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Re: LF501EM5F No Power, Chirping/Beeping Transformer
Oh wow you're right. I hadn't noticed the labels before but now they jump out at me. A 2nd pair of eyes on a problem is invaluable! Thanks! I'll do some prodding and report backLeave a comment:
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Re: LF501EM5F No Power, Chirping/Beeping Transformer
It stops ticking when the cable is removed. Starts ticking again when the cable is reinserted.Leave a comment:
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Re: LF501EM5F No Power, Chirping/Beeping Transformer
yes of course, I tested all of them. I noticed the SMD diodes that are situated near multiple resistors tested bad in circuit but after removing them i see they're goodLeave a comment:
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Re: LF501EM5F No Power, Chirping/Beeping Transformer
I do have a DMM. I tested most if not all diodes. I just double checked the ones i've boxed in red in this picture, are these what you'd consider output diodes?...Leave a comment:
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Re: LF501EM5F No Power, Chirping/Beeping Transformer
Thanks for the response. I tried that, no change.Leave a comment:
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LF501EM5F No Power, Chirping/Beeping Transformer
Preface: I know these walmart black friday tv's are real piles of crap..
Emerson LF501EM5F LED TV
As soon as it's plugged in (to mains) it starts to "chirp" at around 2 second intervals repeatedly and will not power on.
Took the cover off and it seems to be originating in or around the bottom right transformer. I believe I tested all the diodes I could find, including the surface mount ones on the back and any that were 0.3v or lower I removed and retested, but they all seem good. Same with the mosfets. The main filter cap has ~160vdc when it's plugged... -
Re: TLX-04240B Backlights Attempt to Fire Up, Over and Over
(speak of the budm and and budm appears!)
Thanks for the response! I have checked each ballast cap on both inverter boards. They all show infinite resistance. (when you say "inverter boards" you're referring to the 2 long boards on either side of the TV, correct? Even though the actual backlight inverter transformers are on the same board as the power supply?)
I also unplugged, sprayed contact cleaner, and re-seated all 20 of the lamp connectors after looking closely for shorts and bad joints....Leave a comment:
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Re: TLX-04240B Backlights Attempt to Fire Up, Over and Over
Also here are the voltages on CON4 and CON3 on the bottom of the power board:
CON4: [B](TV OFF)------(TV ON)[/B]
GND: 0.00v---------------0.00v
EPWM: N/A---------------N/A
BK_ON: 0.00v------------4.54v
FDATA2: N/A-------------N/A
FDATA1: N/A-------------N/A
APWM: 0.48V------------3.08v~3.20v
CON3:
+Vo: 0.13v--------------24.9v
oGND: 0.00v--------------0.00v
GND: 0.00v---------------0.00v
GND: 0.00v---------------0.00v...Leave a comment:
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TLX-04240B Backlights Attempt to Fire Up, Over and Over
Hello! First time poster, though I frequently lurk around trying to learn things. I have this garbage (in all senses of the word) Polaroid TLX-04240B LCD TV which I would like to get working, with your help.
The issue:
When I turn on the TV the backlights fire up for a split second, then a faint *Click* can be heard and the backlights shut right off (2 seconds to black). However, a second later the backlights attempt to fire back up, *click*, and then shut off again. This process repeats, with the same rhythm, forever or until I press the power button and shut it... -
Re: New Members - please post your introductions here
Hello! Mike from New Jersey here.
Just your average tinkerer/do-it-yourselfer/hobbyist with a desire to learn.
My usual mode of operation is as follows:
-Locate something "broken".
-Attempt to "fix" it.
-Fail.
-Refer to Internet (which, as of late, has led to me Badcaps.net more often than not).
I recently acquired 4 broken LCD TV's, (two of which I have been able to fix thanks to this forum) and I figured it's time to post my introduction.
Thanks...Leave a comment:
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