Re: Philips 42PFL7422D/37 Backlight Issue
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jthi
Member
Last Activity: 01-27-2012, 06:50 PM
Joined: 01-13-2012
Location: Dallas, TX
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Re: Philips 42PFL7422D/37 Backlight Issue
Ding Ding. Four bad bulbs - wish it was less, but at least I know what to look for.
Tom - any tips on unseating these bulbs from their holders? The don't seem to want to pop out by hand easily.Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thank you Tom. I'll work on getting it half together and testing. I've been keeping my eyes open on craigslist, but so far, no luck with and broken 42" tvs.Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
I manned up and finally took the tv all the way apart, and it looks like I've got 3 ccfls that are bad. I've attached pics. This brings me to my next set of amateur quetions:
1) Can I connect back up all the powers (less the tcon and LCD connection) and powe the tv up to see which bulbs will flash on during that initial 2 secs?
2) Does anyone know a good place to find replacement bulbs? From what I've googled, I can't easily find a part number, just sites with sizes listed. These are 4mm diameter, and I'm not...Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thanks Retiredcaps. Does that mean that the inverters sound like they're probably good? I can try and do the rolled up paper test and listen for anything strange out of the transformers.
I'm guessing these inverters are going into some type of lock down mode and cutting the power off intentionally. After reading that other linked post, my best thought is to try and inspect the ccfl bulbs. I didn't see any results from the previous thread poster on how that turned out for him, but hopefully it will be a clue into my next s...Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Other Pin combos if needed:
Old Master T1:
Pin 4-5,6,7: 0.3 Ohms
Pin 4-8: 8.39k Ohms
Pin 5-6,7: 0.3 Ohms
Pin 5-8: 8.40k Ohms
Pin 6-7: 0.3 Ohms
Pin 6-8: 8.37k Ohms
Pin 7-8: 8.41k Ohms
Old Master T2:
Pin 4-5,6,7: 0.3 Ohms
Pin 4-8: 8.34k Ohms
Pin 5-6,7: 0.3 Ohms
Pin 5-8: 8.37k Ohms
Pin 6-7: 0.3 Ohms
Pin 6-8: 8.39k Ohms
Pin 7-8: 8.35k OhmsLeave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thank you for all the newbie patience. I've attached a picture with the pins labled. Here are my combo testing results. All combinations not listed read as open/OOR:
Old Master T1:
Pin 2-4: 8.49k Ohms
Pin 2-5: 8.49k Ohms
Pin 2-6: 8.47k Ohms
Pin 2-7: 8.48k Ohms
Pin 2-8: 23.3 Ohms
Old Master T2:
Pin 1-2: 0.3 Ohms
Pin 1-4: 8.39k Ohms
Pin 1-5: 8.39k Ohms
Pin 1-6: 8.38k Ohms
Pin 1-7: 8.47k Ohms
Pin 1-8: 23.4 Ohms
Pin 2-4: 8.45k Ohms
...Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thanks retirecaps - I think I was typing out my long reply above before I saw your post. The above readings are with S1 and S2 on opposite sides of the transformer. On T1, S1 is the outer most corner pin (where I have the black probe on the Master_old picture above), and S2 is the first pin from the left on the opposite side. I did not grab a picture of me testing like that, but I can if needed.Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
I checked out the LCDparts website that retiredcaps previous post directed me to, and the closed match I could find suggested that S1 and S2 are like my attachment indicates. When I test those points, here are the resistances I get:
Old Master Inverter:
T1 (edge): S1 to S2 = Open (on 20k Ohms setting)
T2 (inside): S1 to S2 = 22.5 Ohms (on 200 Ohm setting)
New Master Inverter:
T1 (edge): S1 to S2 = Open (on 20k Ohms setting)
T2 (inside): S1 to S2 = 23.2 Ohms (on 200 Ohm setting)...Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Here are some better pictures of the original boards I have placed in the TV....Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thank you sir. Let me start working through that, and I will get some better pictures up.Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Retiredcaps - Is it possible I wasn't doing something right when reading the resistance? I tried putting the probes everywhere I could (on the solder, on each pins, etc) and I couldn't get anything besides open on them.
Here's what I see on the sides of the transformers:
Old:
T51 0165 211 e1
0726 70 8S
New:
T51.0165.211 e2
0734 70 9SLeave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thank you Tom for the quick help! I measured Red to Red as Open (1 on the left), Blue to Blue as closed (0.3 Ohms on 200 setting), and Green to Green measured as closed (0.3 Ohms on 200 setting) as well.
I swapped to my old board to check it as well and received the exact same readings on all 3. If I lable your left most red mark as 1, I can measure Red 1 to Blue 1 as open and Red 2 to Blue 1 as closed. Not sure if that's anything valid for the two transforms, but thought I'd throw it in there.Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
The basic Crafstman DMM...Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Tom - highlighted tests would be a great help for me! Do I need to upload a different picture than the 4th one up above? I do have a multimeter, just a little direction on where to put the probes would be great. Thank you!
bbjunkie - how are you able to fool the inverter into not cutting out?Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Thanks for the reply Tom. I can quickly hit the menu button during that initial 2 secs, and everything across the screen looks good.
I'm starting to wonder if my replacement Master Inverter might be bad as well, but that's just me taking a guess.Leave a comment:
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Re: Philips 42PFL7422D/37 Backlight Issue
Updating with photos - hopefully they help...Leave a comment:
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Philips 42PFL7422D/37 Backlight Issue
Hey Forum,
This place has been a huge help in reading through, but I'm still having some issues tracing down my issue. I'm a home DIYer, so I don't have access to some of the specific tools I read others using, pretty much just the standard multimeter.
With that as a preface, on to my issue. I received the tv from my brother with the symptoms of no video but it does get sound. I can see with a flashlight, that the picture is there, but there is no backlight. The specifics on what actually happens is this: when I plug in the TV, I hear a relay click, and then I power...
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