Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
No test patterns were observed.
No test patterns were observed.
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
OK, show me a picture of your control board with this set up, I need to check it is all correct.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Ask and ye shall receive. Still no Test Pattern, the included photo is what I did per instructions.
I received the Y-Main repair kit and have begun replacing sets of FETs. So far, I have replaced both IRFP4332 and the one in U5407 still gets ridiculously hot.Attached FilesComment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
OK, looks good
With this setup still connected as is, please try to check the Vsc voltage on the Y-main.
Also, we need to check Vsch, for this, we will need to see a clear picture of around the scan drive ("buffer") chips on the Y-main.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
X-Main
VCC = 15.1VDC
Vss = 209
Y-Main
Va = 54.7VDC
Vc = 15.1VDC
VS = 209VDC
Logic Board
D5.3 = 5.2VDC
BIG UPDATE - After replacing the IRFP4332 FETs on the Y-Main, now I do not even get a flicker on the screen.
- Neither IRFP4332 FET is getting warm now.
- Found bottom-most Buffer U5407 @ 115 degrees F. Hot, but not hatefulComment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Can you post a pic of the long board running along the bottom of the set. We need to check the Va fuse.
Also, do you have any access to an oscilloscope?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
All fuses on X-Main, Y-Main, Logic Board, Z-Buffer(?..... along bottom of TV) are all good.
Yeah, I have access to an O-scope. Where shall I check?Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
That's the address buffer
OK, scope is good. Show me a pic of what you got.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Ask and Ye shall receive!Attached FilesComment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Sorry...meant the scope!Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
One O-Scope of varying sizes and degrees in the workshop.Attached FilesComment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
A bump to keep it fresh
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Sorry, got delayed...
See this
Scope probe tip (using hook) on red area
Ground on black area. Make sure it's secure.
Caution: Sustain output is up to 400V DC! Keep hands well away during probing, and make all probe changes with TV power off.
Scope probe on 10X.
Scope V/div on 10V/div, make sure scope is also set to 10X.
Timebase 50ms/div, trigger AUTO, type EDGE or LINE, source LINE (if EDGE).
Connect to Ch1 and enable and run the scope then stop it when you see something.
Show me what you get with the set powered on in test pattern mode.Attached FilesPlease do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
A whopping 0VDC (zero VDC) at both test points. It is verified with a multimeter.
I also found U5008 and U5011 hot as hell too (190 degrees F) after a couple minutes. So a few more IRFP4332 FETs are on order from Mouser.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Oops, Q5008, Q5011.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Are Vs, Va and Vg present during this fault? And Vsc?
Maybe you should go back to the original parts - a glow from the screen indicates the Y-main was likely working.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
X-Main
VCC = 15.1VDC
Vss = 209
Y-Main
Va = 54.7VDC
Vc = 15.1VDC
VS = 209VDC
Logic Board
D5.3 = 5.2VDC
Do we know what IC or logic is controlling the FETs and what input/output is expected at the FETs?Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
There is a lot of control on the Y-main boards but it is all ultimately controlled by the control board. That controls all of the power electronics signals.
You need to find Vsc as well may be marked as VSCAN.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
Update after a long while.
VSCAN was acting really wonky. It initially looked like I had a signal on startup, but then the IRFP4332 would escalate to 190 degrees F and then VSCAN would shut off.
This is when the investigation really went sideways on this project. I replaced all the IRFP4332 components on the Y-Main and all the results were the same. Fun fact, I think I damaged the TO-247 Heat-transfer pad. One of the IRFP4332 shorted out like a shotgun........ so that was fun.
Anyways, this whole time I was able to find another Y-Main online and ordered it since it seemed most of the issues were on the Y-Main (hot FETs..... and now shorting). Replaced the Y-Main, all is good now.
I wish I could have troubleshot the original Y-Main, maybe again in the future or if I can get my hands on another PN50B450. Thank you all for watching the saga and offering assistance. I've got another few Plasma/LCD TVs in the garage, I'm sure I be posting about those soon. Cheers!
Last edited by brnrubbr; 10-03-2018, 07:13 AM.Comment
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Re: PN50B450 - Turns on, Sound good, I think Backlight is good, No Picture
No problem...glad you sorted it and thanks for feedback.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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I have a 60 inch Samsung UN60EH6000F flatscreen TV. The screen went black a few months ago Sound is good, backlight is good, no menu. I replaced the TCon board with a used board purchased from Ebay. It worked fine for a 3-4 months, then the screen started ‘fading' back. Once again, sound is good, backlight is good, no menu. However, this time the picture looks fine for about 10-15 minutes, then fades back. If I power cycle the TV, the display reappears, for another 10-15 minutes, then fades black again. Repeatable ever time.
I ordered a supposedly ‘new' Tcon board this time, and... -
Hi, I have a Samsung UE50TU with:
- sound and backlight, but no picture
- when it arrived, it had a picture for a few seconds
- it keeps rebooting
- without ribbon cable between the two panel boards, it does not reboot but I have no picture
- without cable between mainboard and lcd panel, it does not reboot (but obviously i have no picture)
- when i try a tape fix, its keeps rebooting, unless I tape off pin 1 (the innermost pin). In that case it does not reboot but I have no picture.
- without cable between mainboard and lcd panel and with a jumpered... -
Hello All
have seen posts on this model in here but my problem sounded different so thought i would create a thread
TV will not turn on
There is no standby light
When I press ON button for remote the red standby light does flash but no picture and no sound
From the back of the TV I can see the red light on the back of the mother board
Holding torch to the screen I cannot see a picture
I removed the back cover
Observing the boards I cannot see any damage
I disconnected the main board from the power supply
the back... -
Hello all,
This is my first post, but long term lurker on the form learning as much as possible about these TV's. I was given this TV as due to a power outage of constant On/off of power to TV. The TV originally would just click on and off (Typical Reboot Cycle). I opened the back of the TV, and troubleshooted by taking the 96 pin LVDS off one at a time to see if I had a picture on either side. I finally fixed the reboot cycle by finding the error on the left side of the screen off connector CN 1301, and the TV would stay on. Further troubleshooting led me to the driver boards where... -
Hello all ~
I’m working on this Samsung 60” LED and purchased a new main board a couple of days ago that did not fix the 5 blink issue. The original main board’s HDMI ports (all 4 of them) failed to work and no amount of reflow remedied that.
This 5 red light blink code on the front panel LED is followed (about 15-20 seconds afterward) by an automatic reboot, and results in 5 more red light blinks. Then the entire cycle repeats itself indefinitely.
No picture. No sound.
I tested all the voltages coming out of the power supply...
Comment