LG 32LH500B - No power, no standby
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Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809 -
Re: LG 32LH500B - No power, no standby
replace R0D9 R2D9 and Z0D5.
English is my first language, and I am not good at spelling or proof reading it seems lolComment
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Re: LG 32LH500B - No power, no standby
You can leave R2D9 out for now since it is for protection not for the circuit to function, every thing else can be put back in place.
More likely that Q0D1 is on right now which it should not be on since AC Voltage is fine..Last edited by budm; 08-12-2020, 08:01 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
-
Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Comment
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Re: LG 32LH500B - No power, no standby
Is the Collector of QOD1 also connected to the Anode of Z0D6?
What is the DC Voltage on Z0D46?
Negative leg of C0D1/COD4 (connected in parallel) is the hot side circuit Ground.
I am trying to draw up the schematic of this sensing circuit.Last edited by budm; 08-12-2020, 09:16 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: LG 32LH500B - No power, no standby
Collector of Q0D1 is attached to the annode of Z0D6 DCV is .54v across Z0D6Comment
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Re: LG 32LH500B - No power, no standby
What resistance do you get in both direction of that ZOD6?
It has R0D5 (394) and COD5 connected in parallel with it.Last edited by budm; 08-12-2020, 10:03 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: LG 32LH500B - No power, no standby
17k on both R0D5 and COD5.
ZOD6 and Q0D1 were measured with out R2D9 in circuit, just so you know.Last edited by JeffJ; 08-12-2020, 10:11 PM.Comment
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Re: LG 32LH500B - No power, no standby
Here is the schematic that I reverse engineer based on what I can see in the pictures.
You should verify it if you can.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: LG 32LH500B - No power, no standby
R0D6 is connected to the emitter of Q0D1 and from R0D6 it goes to R2D9 so they are in series So Q0D1 Emitter -> R0D6 -> R2D9 -> BP
D1D2 you have labeled is actually labeled D1D3 (Markings "M7" on the diode) And its Anode is connected to the Anode of D0D1 in the rectification diodes.
The Main Filter cap - terminal the circuit actually goes to is C0D4 but thats labeling because the filter caps negative sides are tied together.
SO its all basically correct and I do not get 390K across Z0D5 C0D5 and R0D5 Id expect i should so something there is low and its pulling the circuit down. I get 22k Which is super low.
Also i dont have any 3k resistors can i replace R0D9 with a 3.3k one? i assume this should be alright since figure 11 shows R9 for the LNK6777K as 4.7K which i do have as well.Last edited by JeffJ; 08-13-2020, 08:51 AM.Comment
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Re: LG 32LH500B - No power, no standby
Here is a quick draw up with the corrections i made to yours, feel free to suggest if something is wrong.
Edit: Ive removed ZD06 ans its 22K across it, now 389K across R0D5 and C0D5 as expected. So its safe to say this is the failed part... I have no idea its Value is it safe to leave it out?Last edited by JeffJ; 08-13-2020, 09:49 AM.Comment
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Re: LG 32LH500B - No power, no standby
Ok sorry for the rapid posting, I replaced R0D9 with a 4.7K SMD because thats what i had and the Diagram for LMK677K suggested this was a valid option.
I removed ZD06 IT was shorted, well it was 22K which was very low.
I put it all back together with out ZD06, everything else is populated on the board as it should be (put R2D9 and R0D9 back on the board)
Now i get 12vdc at the Base of the PNP transistor and BP now reads 7VDC suggesting its no longer running on its internal regulator and is running on the aux winding.
The tv powers up and works perfect now.
SO is it safe to just leave out the Zeener i removed? If not how do we tell the value of what should be there.
I know the back is labled 120v 1.2A but this TV is only pulling 25W according to my battery backup. Just as an observation.
I would call this TV fixed as long as their is no Health/fire hazard leaving it as it is.Last edited by JeffJ; 08-13-2020, 11:13 AM.Comment
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Re: LG 32LH500B - No power, no standby
So if the BP is 7V then the Zener Didoe has to be higher than 7V to keep the Transistor off and since typical E-B reverse bias Voltage it can handle is about 5V, right now we are at about 5V without Zener in place because you have 12V at the Base, I would suggest 9.1V Zener so the Transistor will not be damaged.
I am glad we finally fix the problem, thanks to your good clear pictures and your knowledge that I did have to do too much to point you to the right direction.
BTW, you should add 'K' to those 470K resistors.
This thread should help other people with the same model in the future as well.Last edited by budm; 08-13-2020, 12:24 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
-
Re: LG 32LH500B - No power, no standby
So if the BP is 7V then the Zener Didoe has to be higher than 7V to keep the Transistor off and since typical E-B reverse bias Voltage it can handle is about 5V, right we are at about 5V without Zener in place because you have 12V at the Base, I would suggest 9.1V Zener
I am glad we finally fix the problem, thanks to your good clear pictures and your knowledge that I did have to do too much to point you to the right direction.
BTW, you should add 'K' to those 470K resistors.
This thread should help other people with the same model in the future as well.Comment
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Re: LG 32LH500B - No power, no standby
The Transistor may fail if AC Voltage goes higer since we are at the 5V limit already.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
-
Re: LG 32LH500B - No power, no standby
Attached is the finished schematic with the 470K resistors labeled as such.Comment
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Re: LG 32LH500B - No power, no standby
So if the BP is 7V then the Zener Didoe has to be higher than 7V to keep the Transistor off and since typical E-B reverse bias Voltage it can handle is about 5V, right now we are at about 5V without Zener in place because you have 12V at the Base, I would suggest 9.1V Zener so the Transistor will not be damaged.
I am glad we finally fix the problem, thanks to your good clear pictures and your knowledge that I did have to do too much to point you to the right direction.
BTW, you should add 'K' to those 470K resistors.
This thread should help other people with the same model in the future as well.
https://www.digikey.ca/en/products/d...1-GS08/4934142
Edit, I just put fresh batteries in my meter and retested the voltage on BP to be sure, and its consistently 6.4VDC, 12.5VDC on the Base of Q0D1.
Is a 9.1 VZ for D0D6 still acceptable?Last edited by JeffJ; 08-13-2020, 01:24 PM.Comment
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