Andersson TV LED4345UHDA not starting

[petax]

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. The voltage of the white connector(going to the background light?) is around 4-5 volts when its cable is not plugged in

Instead of investigating the power supply more I bought a used one on ebay and installed it. The TV still don't start up and when testing the “new” power supply it has the same problems, good voltage when nothing is plugged in and the 12v out goes to almost zero when the 12v 5w lamp is plugged in. The white contact also has 4-5v when its cable is not plugged in. However, the power supply seemed to work for a few seconds when I pulled and pushed on the 230v wall outlet cable close to the power supply. The 12v lamp and the backlight lit up for a short time. Then I thought that the 230v cable or its contact to the power supply was bad, so I changed to another one. To rule out the contact I soldered the new cable directly to the pins of the power supply, but it didn't solve the problem. I have two theories about this:

1. The “new” power supply wasn't functioning and has similar problems as the old one. How should I continue troubleshooting the power supply?
2. There is a shortcut on the main board which broke something in the “new” power supply when I plugged it in, maybe I have to troubleshoot the main board too?

[petax]

Re: Andersson TV LED4345UHDA not starting

Anyone have any ideas?

[Diah]

Re: Andersson TV LED4345UHDA not starting

he black connector are giving the correct voltage, 5, 12, 24v etc. However, when I load the 12v output with a 12v 5w lamp,

1-where did you read or saw about the 5W lamp to use...?? dont do it again if you want urs TV PWB not toasted.
2- the PWB are fine since all voltage as it should.
3- MB send PWR_ON. this why the PWB produced the needed Voltage lines. at this point i think you can see faint picture on the screen if u used touch light
4- as you are limited with electronic...first buy LED tester and test your TV BL

[petax]

Re: Andersson TV LED4345UHDA not starting

1-where did you read or saw about the 5W lamp to use...?? dont do it again if you want urs TV PWB not toasted.
2- the PWB are fine since all voltage as it should.
3- MB send PWR_ON. this why the PWB produced the needed Voltage lines. at this point i think you can see faint picture on the screen if u used touch light
4- as you are limited with electronic...first buy LED tester and test your TV BL

I read about testing with a light bulb in the LCD TV repair guide, maybe I misinterpreted the guide?
https://www.badcaps.net/forum/showth...956#post305956

I didnt see anything showing on the screen with the flashlight.

Is there any specific led tester thats recommended?

[nomoresonys]

Re: Andersson TV LED4345UHDA not starting

This one has good specs. 300 (V) 350 (mA), could get a cheaper one but most in the 20-30 range only go to 35 mA, which isn't enough for completely accurate testing, just an example, looks like a pretty long wait for that particular one from china: https://www.ebay.com/itm/38487393391...ampid%3APL_CLK

[petax]

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.

[nomoresonys]

Re: Andersson TV LED4345UHDA not starting

Wonder if it's a mainboard issue, as in mainboard not sending backlight on signal.

[petax]

Re: Andersson TV LED4345UHDA not starting

Wonder if it's a mainboard issue, as in mainboard not sending backlight on signal.

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.

[nomoresonys]

Re: Andersson TV LED4345UHDA not starting

Might need to go higher temps to melt the solder, a lot of ovens are not too precise on temperature, also need to be careful not to melt the plastic parts when doing a home oven reflow, a little reading there with profile on reflows, hard to match exactly with home diy, but one can try: https://www.pcbonline.com/blog/pcb-l...soldering.html

[petax]

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 model?

[nomoresonys]

Re: Andersson TV LED4345UHDA not starting

I have to leave that to the vestel pros, I see very few vestel boards here in the States.

[R_J]

Re: Andersson TV LED4345UHDA not starting

The power supply boards give both 12v and 24v but no 5v when I test the output pins, maybe 5v standby is not needed?

Check if Q18 is populated on the power supply board, if it is not then the power supply does NOT provide the +5V_STBY
This is an always on power supply so it provides +12v & +24v at low current in standby mode, (the main board will provide all the lower voltages)
These power supply boards are a universal board and can be configured many ways depending on the manufacture who uses them.
There should also be a number on the power supply board 17IPS72-Rx where x is the revision number

The ST_BY pin (CN3 pin3) is the power supply ON/OFF signal coming from the main board, does this voltage change when the power button is pressed?
BL_ON-OFF is the backlight control pin

[petax]

Re: Andersson TV LED4345UHDA not starting

Check if Q18 is populated on the power supply board, if it is not then the power supply does NOT provide the +5V_STBY
This is an always on power supply so it provides +12v & +24v at low current in standby mode, (the main board will provide all the lower voltages)
These power supply boards are a universal board and can be configured many ways depending on the manufacture who uses them.
There should also be a number on the power supply board 17IPS72-Rx where x is the revision number

The ST_BY pin (CN3 pin3) is the power supply ON/OFF signal coming from the main board, does this voltage change when the power button is pressed?
BL_ON-OFF is the backlight control pin

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.

[R_J]

Re: Andersson TV LED4345UHDA not starting

Your fault is likely with the main board, The reason you can't test it with your 12v5w lamp is that the power supply is in standby, so the pfc circuit will not be operating and the main smps will likely be in burst mode only, so only enough current is supplied to keep the main board alive and in standby.

[petax]

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?

https://www.ebay.com/itm/37443683718...Bk9SR5adj5_tYQ

[petax]

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 measured resistance on most of the capacitors on the mainboard and haven't find any shortcuts.

I have a thermal camera which maybe could be used to identify heated components if that could be used in troubleshooting?

[petax]

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.