Samsung UN65MU8000FXZA Dead NO power NO standby light won't turn on

rgla · 11-27-2021, 02:20 PM

Hi. First time post. I've scoured the previous forums looking for info - there isn't much for my model
UN65MU8000FXZA

We had a power outage. Everything plugged into the Monster surge protector seems to be fine except my Samsung TV. It was dead when the power came back to the house.

Here's what I've looked at:
Unplugged main board from power supply - BACKLIGHTS COME ON.

Ordered new main board - still didn't work. Not sure if used MB was DOA

MAIN BOARD = BN94-12295K
PSB= BN44-00912 L65E8NR_MHS

There doesn't seem to be a pin for Standby like on other boards
The value on pin 16. power on/off seems high but what do I know.

Please help me diagnose - is the power supply board done?

Here are the values I tested for VOLTS. I didn't have the needle tips for multimeter so made my own but here are the values
WITH = with MB connected
WO = without MB connected

CNM803 WITH WO
1. GND 0 0
2. GND 0 0
3. GND 0 0
4. GND 0 0
5. VAMP 9 12.85
6. GND 0 0
7. VAMP 9 12.85
8. OD_LEVL 0 3.2
9. VAMP 9 12.85
10 FAIL COUNT 0 13
11 A13V 9 12.85
12 OD ON OFF 0 3.2
13 A13V 9 12.85
14 BLU 0 3.2
15 A13V 9 12.5
16 POWER ON/OFF 96 4.5
17 A13V 9 12.85
18 GND 0 0
19 GND 0 0
20 GND 0 0

**dskall** · 11-27-2021, 04:34 PM

16 POWER ON/OFF 96 4.5? 96vdc?

**dick_barton** · 11-28-2021, 07:28 AM

Maybe 96mV?

**dskall** · 11-28-2021, 10:57 AM

What voltages does the old mainboard have? Seems the mainboard is pulling down your 13v line.

rgla · 11-28-2021, 11:04 PM

Yes the 96 is VDC. I didn't move the Meter to another setting.
It seemed high to me. This was only when the cable from PB to MB was disconnected. There's actually 2 cables running from PB to MB.

I got another mainboard today but it was one letter off
BN94-12295K (original board) BN94-12295J - new board. The backlights started flashing and I think the standby light was flashing. The repair shop said it must be the MB but I'm not convinced. He wasted to solder a part from the J board to my K board and said it would probably work.

I don't want to buy a new MB and have the PB fry it.
This did happen after a power outage so maybe it was a one time surge?

Thanks for the help

rgla · 11-28-2021, 11:10 PM

I'm pretty new to this so excuse this question.
I did find a "pin" in the middle of the power board that says "stndby" 7.5 ON 11
Not sure what this is called - a pin? it looks almost like a staple that's about an inch long. How do I test this? set meter to VDC, Ground the black meter probe to the body of the TV and touch the red probe to the staple/pin (it's in the middle of the board and doesn't have a cable or anything near it.

**dskall** · 11-29-2021, 10:23 AM

Need some pictures of connectors and boards.

rgla · 11-29-2021, 10:39 AM

Here are the images.
Thanks for the help.

**dick_barton** · 11-29-2021, 01:07 PM

You can measure the voltage on that link and see if it is at 7.V volts when in standby and 11.8V when out of standby. Meter set to dc voltage and can use the chassis as ground.

rgla · 11-30-2021, 10:50 AM

Thanks for the follow up help. Here are the voltages I got on the standby link (jumper?) (HOT side of board)
The TV was not ON. It was just plugged in. It won't turn on so I'm not sure how to assess the info from the board:
According to the board it should be 7.5 standby and 11.8 on.

With the main board connected the voltage was 9v
Withe the main board DISCONNECTED the voltage was 12.85

somewhat similar to what I was getting at the cable connection pins.
Still not sure if the power on/off connection cable pin is supposed to be 96 and then down to 4.5

**dskall** · 11-30-2021, 11:15 AM

That does not appear to be hot side. All voltages on that side taken from cold side ground as on pads for screw holes.

**vinceroger69** · 11-30-2021, 11:24 AM

This maybe worth a read
https://masterelectronicsrepair.blog...amsung_98.html

rgla · 11-30-2021, 11:44 AM

Sorry. You are correct. This is on the COLD side.
I put the black probe in a screw hole on the chassis of the tv.
Does any of that matter for the reading?

**dskall** · 11-30-2021, 11:55 AM

Hot side ground and cold side ground are 2 different things. Your voltage readings are odd. As in 96v doesn't seem valid. Are your batteries good in your voltmeter?

rgla · 11-30-2021, 08:21 PM

All the voltage readings I took were on the cold side. I grounded to a screw hole / chassis in the back of the TV.
New batteries, new multimeter.

It seems like the other readings were fine so I suspect the 96 is a correct reading. As soon as I disconnect the main board it goes down to 4.5

Why would the standby jumper pin not measure 7.5 or 11.8?
With the main board connected the voltage was 9v
Withe the main board DISCONNECTED the voltage was 12.85

**dskall** · 11-30-2021, 10:16 PM

Are those voltages with old mainboard or new? Are you sure pin 16 was not .96vdc.

rgla · 11-30-2021, 10:18 PM

Old mainboard. I don't have the new one yet. Hard to find and even harder to find someone who wants to look into the problem with the board and fix it.

**dskall** · 11-30-2021, 10:37 PM

Seems you have a bad mainboard.

**vinceroger69** · 12-01-2021, 03:07 AM

Quote:

Originally Posted by rgla

Old mainboard. I don't have the new one yet. Hard to find and even harder to find someone who wants to look into the problem with the board and fix it.

This is the only site i can see who has any in stock not cheap though
https://www.tvpartstoday.com/BN94-12...n94-12295k.htm

**lotas** · 12-01-2021, 04:16 AM

Most likely, the firmware of the standby mode IC1604 25Q40 flew off, as always in the "MU" series. Do you have main BN41-02570B?

11-27-2021, 02:20 PM	#1
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Samsung UN65MU8000FXZA Dead NO power NO standby light won't turn on Hi. First time post. I've scoured the previous forums looking for info - there isn't much for my model UN65MU8000FXZA We had a power outage. Everything plugged into the Monster surge protector seems to be fine except my Samsung TV. It was dead when the power came back to the house. Here's what I've looked at: Unplugged main board from power supply - BACKLIGHTS COME ON. Ordered new main board - still didn't work. Not sure if used MB was DOA MAIN BOARD = BN94-12295K PSB= BN44-00912 L65E8NR_MHS There doesn't seem to be a pin for Standby like on other boards The value on pin 16. power on/off seems high but what do I know. Please help me diagnose - is the power supply board done? Here are the values I tested for VOLTS. I didn't have the needle tips for multimeter so made my own but here are the values WITH = with MB connected WO = without MB connected CNM803 WITH WO 1. GND 0 0 2. GND 0 0 3. GND 0 0 4. GND 0 0 5. VAMP 9 12.85 6. GND 0 0 7. VAMP 9 12.85 8. OD_LEVL 0 3.2 9. VAMP 9 12.85 10 FAIL COUNT 0 13 11 A13V 9 12.85 12 OD ON OFF 0 3.2 13 A13V 9 12.85 14 BLU 0 3.2 15 A13V 9 12.5 16 POWER ON/OFF 96 4.5 17 A13V 9 12.85 18 GND 0 0 19 GND 0 0 20 GND 0 0 Last edited by SMDFlea; 12-01-2021 at 05:22 AM.. Reason: UN65MU8000FXZA

11-27-2021, 04:34 PM	#2
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on 16 POWER ON/OFF 96 4.5? 96vdc? __________________ I assume no responsibility for any stupid suggestions I might post.

11-28-2021, 07:28 AM	#3
dick_barton Badcaps Veteran Join Date: Aug 2015 City & State: Cardiff My Country: Wales Line Voltage: 230V AC, 50Hz I'm a: Hobbyist Tech Posts: 6,544	Re: Samsung 65 Dead NO power NO standby light won't turn on Maybe 96mV? __________________ Willing to help but I'm no expert.

11-28-2021, 10:57 AM	#4
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on What voltages does the old mainboard have? Seems the mainboard is pulling down your 13v line.

11-28-2021, 11:04 PM	#5
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Re: Samsung 65 Dead NO power NO standby light won't turn on Yes the 96 is VDC. I didn't move the Meter to another setting. It seemed high to me. This was only when the cable from PB to MB was disconnected. There's actually 2 cables running from PB to MB. I got another mainboard today but it was one letter off BN94-12295K (original board) BN94-12295J - new board. The backlights started flashing and I think the standby light was flashing. The repair shop said it must be the MB but I'm not convinced. He wasted to solder a part from the J board to my K board and said it would probably work. I don't want to buy a new MB and have the PB fry it. This did happen after a power outage so maybe it was a one time surge? Thanks for the help

11-28-2021, 11:10 PM	#6
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Re: Samsung 65 Dead NO power NO standby light won't turn on I'm pretty new to this so excuse this question. I did find a "pin" in the middle of the power board that says "stndby" 7.5 ON 11 Not sure what this is called - a pin? it looks almost like a staple that's about an inch long. How do I test this? set meter to VDC, Ground the black meter probe to the body of the TV and touch the red probe to the staple/pin (it's in the middle of the board and doesn't have a cable or anything near it.

11-29-2021, 10:23 AM	#7
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on Need some pictures of connectors and boards.

11-29-2021, 01:07 PM	#9
dick_barton Badcaps Veteran Join Date: Aug 2015 City & State: Cardiff My Country: Wales Line Voltage: 230V AC, 50Hz I'm a: Hobbyist Tech Posts: 6,544	Re: Samsung 65 Dead NO power NO standby light won't turn on You can measure the voltage on that link and see if it is at 7.V volts when in standby and 11.8V when out of standby. Meter set to dc voltage and can use the chassis as ground.

11-30-2021, 10:50 AM	#10
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Re: Samsung 65 Dead NO power NO standby light won't turn on Thanks for the follow up help. Here are the voltages I got on the standby link (jumper?) (HOT side of board) The TV was not ON. It was just plugged in. It won't turn on so I'm not sure how to assess the info from the board: According to the board it should be 7.5 standby and 11.8 on. With the main board connected the voltage was 9v Withe the main board DISCONNECTED the voltage was 12.85 somewhat similar to what I was getting at the cable connection pins. Still not sure if the power on/off connection cable pin is supposed to be 96 and then down to 4.5

11-30-2021, 11:15 AM	#11
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on That does not appear to be hot side. All voltages on that side taken from cold side ground as on pads for screw holes.

11-30-2021, 11:24 AM	#12
vinceroger69 Badcaps Veteran Join Date: Mar 2012 City & State: Nuneaton Warwickshire My Country: uk I'm a: Hobbyist Tech Posts: 6,406	Re: Samsung 65 Dead NO power NO standby light won't turn on This maybe worth a read https://masterelectronicsrepair.blog...amsung_98.html

11-30-2021, 11:44 AM	#13
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Re: Samsung 65 Dead NO power NO standby light won't turn on Sorry. You are correct. This is on the COLD side. I put the black probe in a screw hole on the chassis of the tv. Does any of that matter for the reading?

11-30-2021, 11:55 AM	#14
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on Hot side ground and cold side ground are 2 different things. Your voltage readings are odd. As in 96v doesn't seem valid. Are your batteries good in your voltmeter?

11-30-2021, 08:21 PM	#15
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Re: Samsung 65 Dead NO power NO standby light won't turn on All the voltage readings I took were on the cold side. I grounded to a screw hole / chassis in the back of the TV. New batteries, new multimeter. It seems like the other readings were fine so I suspect the 96 is a correct reading. As soon as I disconnect the main board it goes down to 4.5 Why would the standby jumper pin not measure 7.5 or 11.8? With the main board connected the voltage was 9v Withe the main board DISCONNECTED the voltage was 12.85

11-30-2021, 10:16 PM	#16
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on Are those voltages with old mainboard or new? Are you sure pin 16 was not .96vdc.

11-30-2021, 10:18 PM	#17
rgla Member Join Date: Nov 2021 City & State: Los Angeles My Country: United States I'm a: Knowledge Seeker Posts: 23	Re: Samsung 65 Dead NO power NO standby light won't turn on Old mainboard. I don't have the new one yet. Hard to find and even harder to find someone who wants to look into the problem with the board and fix it.

11-30-2021, 10:37 PM	#18
dskall Badcaps Veteran Join Date: Oct 2016 City & State: Bakersfield ca. My Country: usa Line Voltage: 120VAC 60Hz I'm a: Knowledge Seeker Posts: 2,806	Re: Samsung 65 Dead NO power NO standby light won't turn on Seems you have a bad mainboard.

12-01-2021, 04:16 AM	#20
lotas Badcaps Veteran Join Date: Jan 2016 City & State: Sochi My Country: russia I'm a: Knowledge Seeker Posts: 868	Re: Samsung 65 Dead NO power NO standby light won't turn on Most likely, the firmware of the standby mode IC1604 25Q40 flew off, as always in the "MU" series. Do you have main BN41-02570B?

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