Author Topic: LG 32LK330 - Voltages go UP and DOWN  (Read 472 times)

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duffy505

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LG 32LK330 - Voltages go UP and DOWN
« on: September 20, 2019,17:45:32 »
Hi.

Tv wont turn on. When i check voltages (3.5V) without main board i get clean and stable 3.5V.
When i connect main board to PSU I get all voltages (12, 24, 3.5 ....) but they go from max to 0V in 5 sec, from max to 0V ....

I have tried to change few capacitors with new one


All diodes are ok, resistors, fuses and i get stable 3.5V until i connect main board. Anyone with same problem ? I did not find anything useful on web (video or text) and dont know what to check next.


Model number 32LK330-ZH
Product Code 32LK330-ZH.BEUYLJP

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LG 32LK330 - Voltages go UP and DOWN
« on: September 20, 2019,17:45:32 »

tv tony

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #1 on: September 22, 2019,07:31:50 »
It sounds as if something is dragging the psu voltages down. Listen very carefully to the psu, is it ticking? You say the 3.3 is constant, I'll look at the manual.
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Davy

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #2 on: September 29, 2019,14:23:00 »
You say 3.5V.... I couldn't see the 5V rail listed.... should it not be 5V and can we confirm the LED standby blinks as well? I'm wondering if this 3.5V should be the 5V supply?

Isn't there a dc to dc converter on the main board that produces 3.2V? I've had the smoothing caps. go faulty causing the set to shut down, can't recall the model.

One laborious way is to disconnect each supply until the 'tripping stops'. Old CRT telly's can lead a merry dance should the emitter or source sensing resistor go high in the power supply chopper.... before the makers got wise and included blink codes, these were often less than an Ohm and the value critical..... would it not be worth another look around the chopper?

Dave

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #2 on: September 29, 2019,14:23:00 »

Turnip

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #3 on: September 30, 2019,12:48:25 »
Hi folks,

Noticed this entry by 'Dave' - Might be useful - Chris.

LG 32LK330
If you get a LG32LK330 or similar with no backlight, with blue power light flashing red after a few seconds, change F2 a 2 Amp surface mounted fuse to the left of the bigger 7 amp one near the middle of the inverter board.

This supplies 25V to the 5V regulator without this there won't be any drive, strangely the fuse had gone high  reading 450 ohm!! The set then ran for two days without further problems.

Dave


Davy

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #4 on: October 06, 2019,10:50:54 »
Thanks Turnip.... I forgot all about that one, apologies to duffy505

I couldn't see anything listed about the 5V supply, I do think there is a 3.2V supply from a converter on the main board, this makes me wonder if the 3.5V should be the 5V supply, reason I  inquired about the standby light.

Dave

duffy505

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #5 on: October 30, 2019,01:42:33 »
Hi

I dont have 5V, you can see on picture markings:




Is this power board problem and Is there any way to connect "fake" load to it to test it (without main board) ?

Did check few more thing but no buzz noise, no heating elements on board (due to short), all fuses are ok., no shorts on rectifier.

Still stable 3.5 V (on all 4 pins) until i connect main board and then voltages oscillates to 0V.


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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #5 on: October 30, 2019,01:42:33 »

downunder

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Re: LG 32LK330 - Voltages go UP and DOWN
« Reply #6 on: November 25, 2019,05:19:28 »

With the pictured plug removed, can you read any shorts on the main board at all the 3.5V terminals?   Bruce

 

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