Re: Hisense 75rge1 led output voltage
It seems like the problem is on the power supply.
With everything plugged in you could measure voltage between GND and B ON. Be careful with the power supply so you don't get an electric schock! I'm not 100 % sure but the B ON should be the control voltage from the main board to activate the backlight. If you don't have any voltage there I would suspect the problem is on the main board(if the main board is supplied with standby power). If there is a few volts at B ON the problem is probably on the power supply....
petax
Member
Last Activity: 04-30-2023, 03:47 AM
Joined: 12-03-2022
Location: Linkoping
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Re: Andersson TV LED4345UHDA not starting
When I made some measurements on the main board, the backlight suddenly came on and now it's on all the time.. I plugged the 230v cable out and then in again, the backlight is on all the time when it's plugged in. It seems like I triggered something on the main board since the BL_ON-OFF now gives 5v. I don't get anything on the screen except backlight when trying to turn it on.
The red led on the optical sound still turns off when applying 3v on the ST_BY pin, but the standby led under the screen stays on.Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
I measured resistance between ground - ST_BY and ground - BL_ON-OFF, no shortcuts on them. With everything connected and plugged in the outlet, I applied 3v from a stand alone power supply on ground - ST_BY and then ground - BL_ON-OFF with the following results:
3v on ground - ST_BY: the red led on the optical sound port shuts down
3v on ground - BL_ON-OFF: backlight is switched on
3v on ground - ST_BY and ground - BL_ON-OFF: no backlight and the red led on the optical sound port shuts down
I have...Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
Is there any point of troubleshooting the main board? The red leds are working(st-by light and optical audio port) and I have measured 5v on the contact going to the st-by light. The st-by light is not reacting when I try to turn on.
I found this board for another tv. It looks the same but I guess I need the specific board for the tv with the correct firmware?
[url]https://www.ebay.com/itm/374436837187?hash=item572e2cb743:g:gWgAAOSwMmNjsenh&amdata=enc%3AAQAHAAAAwMw%2FaB3UmWs28sdkHcu6c45YIh0vZu68Y%2FltDf...Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
Q18 is not populated so the power supply should not deliver 5v. The ST_BY pin does not change voltage when I try to turn on, neither with remote or button on tv....Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
I might try reflowing at a higher temp as a last resort. Since I have tried another power supply board as described above, my guess is that the problem is at the mainboard. I have tested the one surface mounted capacitor on the mainboard with good values. The power supply boards give both 12v and 24v but no 5v when I test the output pins, maybe 5v standby is not needed?
I can find 17mb170e main board that looks the same but is from a larger tv of a different brand. I guess I have to find a mainboard specific to this tv mo...Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
I just tried reflowing the main board by baking it in the oven at 200 deg C for 10 minutes but it made no change....Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
I have now tried the backlight with 9v batteries in series. I have demounted the screen and all LEDs is working fine when i power the backlight with around 80v(from batteries) from the main cable on the power supply.
I have tried turning the tv on both from the button on the tv and the remote control, nothing happens. The backlight only gets around 5v(should be 92v). There is both 12v and 24v output from the power supply to the main board.Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
I read about testing with a light bulb in the LCD TV repair guide, maybe I misinterpreted the guide?
[url]https://www.badcaps.net/forum/showthread.php?p=305956#post305956[/url]
I didnt see anything showing on the screen with the flashlight.
Is there any specific led tester thats recommended?Re: Andersson TV LED4345UHDA not sta...st305956[/url]...Leave a comment:
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Re: Andersson TV LED4345UHDA not starting
Anyone have any ideas?Leave a comment:
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Andersson TV LED4345UHDA not starting
I have an Andersson LED4345UHDA where the red led lights up when plugging in but doesn't start by the remote or the button on the tv. I have also tried a new remote.
It has a Vestel 17IPS72 power supply and a 17MB170E board as seen in the picture. It seems like all outputs on the black connector are giving the correct voltage, 5, 12, 24v etc. However, when I load the 12v output with a 12v 5w lamp, there is no light and the voltage drops close to zero. I am no electronics pro but I looked at the capacitors on the board and couldn't see anything wrong. I haven't made any measurements on components.... -
Re: New Members - please post your introductions here
Hello, my name is Peter and I am from Sweden. I have repaired a few electronic devices before and I really like doing it. Right now I am trying to repair a TV, which led my to this forum that seems to have a lot of competence regarding electronics.Leave a comment:
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