Re: LG 50PQ6000 unstable 5v standby
They would work. Put one across the 4.45V output. Does it stay at 4.45V?
They would work. Put one across the 4.45V output. Does it stay at 4.45V?
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Re: LG 50PQ6000 unstable 5v standby
How do two in series (20 ohm) make it drop by?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: LG 50PQ6000 unstable 5v standby
Back up to 4.45VRepaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
Hmm, so maybe that is normal, it might not be designed to support 445mA load. It's probably not bad caps, if it does that. So I really don't know any more. I am out of ideas. I am of course assuming your DMM is correct. Have you checked it against a known good voltage source?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: LG 50PQ6000 unstable 5v standby
DVM is fine. I have 2.
I have tried using an old computer power supply and injecting 5v to see if anything got hot and that voltage dropped too and made me wounder.
Looking in the training manual everything says 5v not 4.45v hummmmm
I hear the relays click and parts of the TV fire for a second then off. Something is up in there somewhere.Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
Wait, so when you fed 5V from computer PSU into output of plasma PSU, it dropped??Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: LG 50PQ6000 unstable 5v standby
yes. Made me think some thing was deadish.Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
something is creating an ubnormal load?Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
But I do not understand how a computer PSU which is completely different would drop down to the same voltage.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: LG 50PQ6000 unstable 5v standby
Im not even sure if it was a propper test in all honesty.
I was still working on the theory that my 5v standby was low. If I have a good 5v standby voltage to start with I would be prepared to move on with different tests and look elsewhere.
I thought I would use one of the 5VDC lines on the computer PSU and just attach it to the standby 5v line to see if it brought the voltage up or maybe caused some heat somewhere for a clue. If I had a test bench power supply I would of tried that. The computer PSU was dragged down I need to retest for the exact results. Maybe there is some mileage in it.Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
I would consider that idea, but the fact that you've got 4.45V under no load tells me something else is wrong with the PSU.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: LG 50PQ6000 unstable 5v standby
Yeah agreed.
So I need to trace the 4.45V back and find out where its developed from.Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
Ok IC301 could be something to do with it. Its a str w6252 9531p ssome kind of protection device if it was playing up it would effect the standby 5v.
Also need to work out what tappings on the coil I need to look at and the 3 components strapped to the heat sink what they should measure.
Its hard to see how exactly the 5v standby is made by following the tracks. Does any one have a simular circuit diagram or have they done it before?
Circled in blue.
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Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
Not given up on this im just building up the insperation for another session.
Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
Does any one know of a link that talks through the path and demonstrates how the standby 5v is made?
I have tried to follow the tracks back but they just dissapear.
I feel if I could wok out how the sb5v is produced I could start looking at the components inline and testing them.
Hopefully then working out why I have a low 5vSB might hold a clue. Also maybe I could follow the path and lift a leg on a component to see if the voltage goes upto 5v again indecating a short?Repaired: LG50PQ6000Comment
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Re: LG 50PQ6000 unstable 5v standby
It just comes from the transformer, goes through a diode, into a capacitor.
There's a feedback loop to regulate it too.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Re: LG 50PQ6000 unstable 5v standby
AC Voltage is supplied to the SMPS Board at Connector SC101 from the AC Input assembly. Standby 5V is developed from 160V source supply (which during run measures 380V measured fromthe primary fuse F302).
This supply is also used to generate all other voltages on the SMPS. The STBY5V (standby) is B+ for the Controller (IC701) on the SMPS and output at P813 pins 11 and 23 then sent to the Main board for Microprocessor (IC1) operation.
So it looks like a good place to start. I should measure 160V across F302 in standby and 380v in run.
Please could I just confirm im measuring across the fuse and not to ground and is it DC or AC at this point. Im in two minds about the second point so would like a second opintion.
Thanks
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Re: LG 50PQ6000 unstable 5v standby
Your ground ref on the primary is the negative lead of the large caps. Measuring a substantial voltage across a fuse is never good. It indicates the fuse is blown.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
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Hi. I got a Vizio with no power or standby, and won't turn on with remote or button. I checked the voltages on the connector and all read 0.00V or nearly 0(0.050 ON/OFF pin). None of the pins are labeled STB for standby although I do see some 5V pins. Other than the obvious standby led, which isn't coming on, is there a way to check for standby voltage on this PS. I'm trying to see if my problem is the PS or mainboard. Some Vizios I have fixed with no standby led me to think it was the PS but it turned out being the mainboard. Any experience with this set would be greatly appreciated. -
Hi all.
I started a thread while back regarding TV power supply standby circuitry as it is something I am not quite on top of.
SMPS theory and function is becoming more familiar, however the standby part is still a bit of a mystery.
Anyway, a friend has this TV with the above mentioned power supply board which has no standby voltage, nor any other voltages leaving the board.
The mains AC comes in fine, gets filtered and rectified with power is on the main filter cap as well as the transformer and drain pins of the ICE3B0665J, but that's it.
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Hello forum. I've recently been given a Yamaha TSX 120 DAB radio and ipod dock. Its working well however when put on standby its using 6.3 watts. The manual states less than 1 watt on standby. I measured this with a plug in monitor which seems accurate with other items. In use it uses around 7.5 watts. Firstly has anyone who owns a similar radio also got a plug in monitor to check if this is normal with this unit? In the first half a second the monitor shows 0.3 watts which I suspect is what it should use but something is switching it to be almost fully powered. I've searched the manual for eco...03-01-2024, 07:25 AM -
Hello everyone,
I got a Samsung The Frame 55 inch TV for free from uncle cause it is not turning on anymore. I am in the second year of training as an electrician so I have knowledge already but I am far away from to be a pro.
The TV has Standby but ist not turning on. A Friend of mine owns a 50 inch Frame TV so I checked the One Connect Box and the One Connect Cable there. Both are good and working normally. I have opened the TV case and measured some voltages on the Board.
What I already found is that the 12.8V are not an the connector to the main board connector to the power... -
Hello,
I am trying to re-purpose this power supply that I saved years ago from a tv with a cracked screen for a monitor but that is not really that relevent at the moment. I do not recall which tv but a google search looks like it is from Wharfedale LTF37K1.
You may notice I made some alterations moving some components to the top and some wires which are from a 5v regulator I fitted to the 12v output as the monitor requires 5v. The standby was already at fault from the beginning, it has nothing to do with the alterations...
Years ago it had some bulging caps...
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