Badcaps Forums

Badcaps Forums (https://www.badcaps.net/forum/index.php)
-   Troubleshooting TVs and Video Sources (https://www.badcaps.net/forum/forumdisplay.php?f=31)
-   -   Samsung LE40B620R3W shuts down (https://www.badcaps.net/forum/showthread.php?t=89555)

Ukdigger 10-15-2020 07:15 AM

Samsung LE40B620R3W shuts down
 
Samsung LE40B620R3WQXU
I'm thinking that the main board may be faulty, I would appreciate any help to test and fix it.
The TV works for about 2 minutes and then shuts down with no standby light. When the main board is disconnected the back lights come on and the TV stays on until powered off.

Voltages on power board

Main board disconnected
4.88
4.88
2.74
12.07
12.07
0
5.01
5.01
0
0
12.07
0
5.01
0.76

Main board connected
4.88
4.88
2.74
12.23
12.23
0
4.95
4.95
0
0
12.23
0
4.95
0.75

nomoresonys 10-15-2020 07:57 AM

Re: Samsung LE40B620R3W shuts down
 
Is there a legend/label on the board describing the pins and the number of the pin?, you put the voltage but we have no way of knowing what it is, so you want to do like, pin 1: ps on 3.3 volts, pin 2 etc. etc.

dick_barton 10-15-2020 08:39 AM

Re: Samsung LE40B620R3W shuts down
 
Post pictures of your power supply board and of the legend as nomoresonys suggests, What is the part number of the power supply BN44-xxxxxx?

Ukdigger 10-15-2020 09:03 AM

Re: Samsung LE40B620R3W shuts down
 
1 Attachment(s)
https://www.badcaps.net/forum/attach...1&d=1602774075

Voltages on power board

Main board disconnected
pin 29 0
pin 27 4.88
pin 25 4.88
pin 23 2.74
pin 21 12.07
pin 19 12.07
pin 17 0
pin 15 5.01
pin 13 5.01
pin 11 0
pin 9 0
pin 7 12.07
pin 5 0
pin 3 5.01
pin 1 0.76

Main board connected
pin 29 0
pin 27 2.68
pin 25 1.79
pin 23 2.74
pin 21 12.23
pin 19 12.23
pin 17 0
pin 15 4.95
pin 13 4.95
pin 11 0
pin 9 0
pin 7 12.23
pin 5 0
pin 3 4.95
pin 1 0.76

[IMG]file:///C:/Users/Mick/Desktop/WP_20201015_15_11_11_Pro[1].jpg[/IMG]

Ukdigger 10-15-2020 09:12 AM

Re: Samsung LE40B620R3W shuts down
 
https://www.badcaps.net/forum/attach...1&d=1602774645

Ukdigger 10-15-2020 09:13 AM

Re: Samsung LE40B620R3W shuts down
 
https://www.badcaps.net/forum/attach...1&d=1602774708

dick_barton 10-15-2020 12:33 PM

Re: Samsung LE40B620R3W shuts down
 
1 Attachment(s)
Your photo is difficult to read. It would make easier reading to list them similar to below. Where are all the even number listings.ie pins 2, 4, 6 ....28
Also what is the board number.

nomoresonys 10-15-2020 09:47 PM

Re: Samsung LE40B620R3W shuts down
 
I think the mainboard isn't sending the proper signal/s.

Ukdigger 10-16-2020 01:05 AM

Re: Samsung LE40B620R3W shuts down
 
1 Attachment(s)
https://www.badcaps.net/forum/attach...1&d=1602832478

Ukdigger 10-16-2020 01:19 AM

Re: Samsung LE40B620R3W shuts down
 
The board number is BN44-00264A. I only tested the pins that had wires coming from them.

vinceroger69 10-16-2020 01:25 AM

Re: Samsung LE40B620R3W shuts down
 
1 Attachment(s)
Quote:

Originally Posted by Ukdigger (Post 995609)
The board number is BN44-00264A. I only tested the pins that had wires coming from them.

psu schematic

nomoresonys 10-16-2020 04:36 AM

Re: Samsung LE40B620R3W shuts down
 
Recheck pin 1, check it with everything hooked up, all boards connected, check in standby which is tv plugged into power but not turned on, which looks like you have .76 v, keeping probes in place hit power button on tv, see if that voltage changes, usually it should be around 3.3 steady v, when tv on and working properly.

Ukdigger 10-16-2020 04:57 AM

Re: Samsung LE40B620R3W shuts down
 
I did what you said and I get 0 volts in standby and when the power button is pressed it shoots up to 0.76 volts

dick_barton 10-16-2020 07:22 AM

Re: Samsung LE40B620R3W shuts down
 
The ON/OFF is connected to the 5.3V Standby rail via RM882 so should be several volts when the mainboard is diconnected from the power supply.
I would measure the dc voltage on the 3 pins of QM802.

Ukdigger 10-16-2020 09:28 AM

Re: Samsung LE40B620R3W shuts down
 
1 Attachment(s)
https://www.badcaps.net/forum/attach...1&d=1602861779


As you look at my photo, I'm getting 0.06 volts of the left pin, 0 volts top right pin and 0.67 volts on the bottom right pin

dick_barton 10-16-2020 09:51 AM

Re: Samsung LE40B620R3W shuts down
 
I think this is an always on power supply. If with the power supply disconnected from the mainboard you jumper a 1K resistor from ON/OFF to ground can you check that only the +5V stanby is running and the other supplies are off.

If this is the case then you probably do have a mainboard fault.

budm 10-16-2020 02:31 PM

Re: Samsung LE40B620R3W shuts down
 
PS-ON of 0.76V is fine since the Base resistor RM864 is only 200 Ohms and RM882 pull-up is 10K.
The circuit is working otherwise you will not have switched 13V right now.
So the question is what are the Voltages at the connector when TV goes into shutdown after 2 minutes?

nomoresonys 10-16-2020 03:33 PM

Re: Samsung LE40B620R3W shuts down
 
Quote:

Originally Posted by budm (Post 995764)
PS-ON of 0.76V is fine since the Base resistor RM864 is only 200 Ohms and RM882 pull-up is 10K.
The circuit is working otherwise you will not have switched 13V right now.
So the question is what are the Voltages at the connector when TV goes into shutdown after 2 minutes?

Ok then, my bad.

Ukdigger 10-17-2020 02:34 AM

Re: Samsung LE40B620R3W shuts down
 
When using 1K resistor from ON/OFF to ground all other voltages were 0 volts, only +5V standby was on. The TV has been working normally now for about 30 minutes. When it goes off again I will test all the voltages and report back.

Ukdigger 10-19-2020 03:31 AM

Re: Samsung LE40B620R3W shuts down
 
1 Attachment(s)
TV was working normally until this morning and then went off with no standby light. Here are the voltages.

https://www.badcaps.net/forum/attach...1&d=1603099828


All times are GMT -6. The time now is 02:39 PM.

Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.