Re: LG 65UH5500 Dead
I finally broke down and ordered a power board. TV works! I'm going to keep the bright levels down low because these are bad for buning out LED backlights. Thanks for the help yall.
hbdeals
Senior Member
Last Activity: 11-08-2020, 04:16 PM
Joined: 10-01-2014
Location: Bristol, TN
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Re: Panasonic LCD TV TH-L32C4K (power board problem?)
Does it only do that while using it as a computer monitor?
I'd disconnect everything, power it up and see if it does that while on the menu screen.Leave a comment:
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Re: LG 65UH5500 Dead
I had removed and checked all of those parts under the heatsink before. They tested ok on a cheapie LCRT4 checker. I don't know how reliable that is. C10 was shorting out and causing Q15 to read .5 ohms. Both the LCRT4 and ohm meter shows C10 as a dead short. It is a (badcap).
All of the electrolytic caps on the power supply test good in circuit with ESR meter....Leave a comment:
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Re: LG 65UH5500 Dead
What are those 2 push button switches for?...Leave a comment:
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Re: LG 65UH5500 Dead
I replaced the optocoupler. No changes.
There's other pins that have no voltage on the middle board (inverter). PWR-ON P-DIM? and DRV-ON.
Not sure how to check those.Leave a comment:
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Re: LG 65UH5500 Dead
Capacitor C10 was bad. Replaced it. The ticking stopped and the voltages are back up.
Hairdryer killed C10 maybe?
80v Pins cycles from 88v-91v
(fail) pin = -300mv
13.2v Pins cycles from 11v-15v
The LED power board (P5141) also cycles 11v-15v on it's 13.2v pins.
Bridge Rectifier input = 124v / output cycles from 168v-176v
Big caps = 386v
Across C56 =19.2v
Opto Pin 1-2 = 1v / Pin 3-4 = 4.6v
I did not replace the optocoupler since C10...Last edited by hbdeals; 07-11-2019, 02:38 PM.Leave a comment:
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Re: LG 65UH5500 Dead
my hot air station is made from a contraption that attaches to a common hair dryer. They burn up after a few months, but hair dryers are really cheap at yard sales....Leave a comment:
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Re: LG 65UH5500 Dead
I haven't changed the opto out yet.
Q15 is reading .5 ohms across the pictured legs.
I wonder... seems really low....Leave a comment:
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Re: LG 65UH5500 Dead
The guy said that the "outlet" it was plugged into "went out". He said the TV worked after that but remembers the speakers crackling one morning and sounding funny. It quit working soon after. Just no power one day.
He says they had too much stuff plugged into the same outlet as the TV and the house isn't grounded....Last edited by hbdeals; 06-08-2019, 08:30 AM.Leave a comment:
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Re: LG 65UH5500 Dead
Heated up the opto a bit = no change
Let it sit = no change
Freeze sprayed the opto = no change...Leave a comment:
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Re: LG 65UH5500 Dead
Voltage across the 3 filter caps is 384 volts now.Leave a comment:
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Re: LG 65UH5500 Dead
I'll see if I can find out from the guy I got it from. It didn't look like anyone had been in it. Thanks for help. I've learned a lot from y'all....Leave a comment:
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Re: LG 65UH5500 Dead
It tics twice as fast with pins 3 and 4 shorted.
80 volts is 44v
13 volts is 7.5vLeave a comment:
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Re: LG 65UH5500 Dead
Do you think these might work?...Leave a comment:
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Re: LG 65UH5500 Dead
I'll see if I have any spares....Leave a comment:
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Re: LG 65UH5500 Dead
Voltage across ZD2 starts out at 3.8 volts, then with each (tic) it drops in voltage until it reaches 2.2 volts and then recycles at 3.8 volts.
Voltage on ZD2 anode= 0 volts (at times it hit .5 volts maybe) strange
Voltage on ZD2 cathode= 2.5 to 3.7 and anywhere in between on the (tics)
80v and 13v are still 45v and 8VLeave a comment:
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Re: LG 65UH5500 Dead
I did that, and get these voltages now.
IC1 Pin 1 = 8.2v
Pin 2 = 7.5v
Across Pins 1 and 2 = pulses to 1.5v...Leave a comment:
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Re: LG 65UH5500 Dead
At least then, it didn't tic. I'm using a good digital meter....Leave a comment:
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Re: LG 65UH5500 Dead
It tics no matter what's connected. I think this TV was a clock in a previous life.
...
Leave a comment:
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Re: LG 65UH5500 Dead
ZD3 cathode is for sure 19.6v
T1 VCC winding 5 to 6 = 0Ω
IC1 Pin 1 = 6.7v
Pin 2 = 5.7v
Across Pins 1 and 2 = .98v (1volt)Leave a comment:
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