Sceptre 40" TV X405BV-FMD8HM07 - No power

[ellisol]

I have a Sceptre 40" TV X405BV-FMD8HM07 I am troubleshooting that has no power and no red power light.

I disconnected the video board and tested power. I have 160+ DCV at the large capacitor and +3.86 DCV at the 5V connector. I have zero DCV at the 12V and 24V connectors.

I am not sure what the fuses look like. I have basic electrical knowledge and have an volt\ohm meter to troubleshoot.

I would appreciate any help this forum can give. I see I can buy a power board for around $60.

Pictures attached

Thanks in advance.

[nomoresonys]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

Test all pins on connector from mainboard to powerbard on powerboard side, all board connected. Test in standby/plugged in but off, then apply power report both conditions, example: pin 1 bl-on=0 volts standby and 3.3 powered on, report results for every pin, this is where most troubleshooting starts, example of testing below in my signature.

[R_J]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

What voltage do you have on the 5VSB pin?

[ellisol]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

The 5VSB pin has +5.23 DCV.

I will test all mainboard to powerboard pins with various power conditions and report back, hopefully tomorrow.

Thanks so much for the quick response.

[ellisol]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

Ok, I tested all pins on the connectors from mainboard to powerbard on powerboard side, with all the board cables connected.

See the attached "Pin numbers.jpg" file for pin numbers. The picture shows the cable disconnected but I tested with them connected. Test was done to chassis ground.

standby/plugged in but off
Pin 1 0 VDC
Pin 2 0 VDC
Pin 3 0 VDC
Pin 4 0 VDC
Pin 5 4.55 VDC
Pin 6 5.24 VDC
Pin 7 0.02 VDC
Pin 8 0.02 VDC
Pin 9 0 VDC
Pin 10 0 VDC
Pin 11 0 VDC
Pin 12 0 VDC
Pin 13 0 VDC

Pin 14 0 VDC
Pin 15 0 VDC
Pin 16 0 VDC
Pin 17 0 VDC

Pin 18 0 VDC
Pin 19 0 VDC
Pin 20 0 VDC
Pin 21 0 VDC
Pin 22 0 VDC
Pin 23 0 VDC
Pin 24 0 VDC
Pin 25 0 VDC

I then pushed the power button and checked voltages again. They were exactly the same. Just like it insn't powering on.

I hope this is what you requested. If not I will make every effort to get what you need. Thanks in advance.

[CapLeaker]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

If you just put a pin number and some voltage, that doesn't tell us anything. We also need to know what the pin is for, like this: PSon 3.5V, BLon 3.5V, GND 0V...

[budm]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

Also It is hard to tell from the picture to know which pins are really tied together or not, I.E. Pin 1, 2, and 3 are Ground pins? 4 & 5 are 5V? 6 is PS-ON?, 7 is 5VSB (5V Standby)?
Your readings seems to indicate that 5VSTBY is 0V but 5V (switched 5V) is present some how, the data does not look right.

[ellisol]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

Sorry I am not providing the right info.

How do I find out the Pin identification for this board? (PSon, BLon, GND, etc)

I did find a table for board MLT666T (My board in MLT666FL) which has a similar layout that further identifies the pin outs. It is attached. (Pin identification table.jpg and Pin identification-rev.jpg )

Based on that info:
standby/plugged in but off

Pin-CON4
Pin 1, 2 GND +5V +5VSB +12VDC RETURN --->0 VDC
Pin 3, 4 +5V +5VDC OUTPUT --->0 VDC
Pin 5 STB SMPS ON/OFF CONTROL(ON = HIGH) --->4.55 VDC
Pin 6 +5VSB STANDBY(+5.0VDC) OUTPUT --->5.24 VDC
Pin 7, 8 +5V +5VDC OUTPUT --->0.02 VDC
Pin 9,10,11 GND +5V +5VSB +12VDC RETURN --->0 VDC
Pin 12,13 +12V +12VDC OUTPUT --->0 VDC

Pin-CON3
Pin 1,2 Vaudio +24VDC OUTPUT ---->0 VDC
Pin 3,4 GND +24VDC RETURN ---->0 VDC

Pin-CON5
Pin 1,2,3,4 +V1 +24VDC OUTPUT ---->0 VDC
Pin 5,6,7,8 GND +24VDC RETURN ---->0 VDC

Does this help?

Again, thanks in advance.

[nomoresonys]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

.

[budm]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

Sorry I am not providing the right info.

How do I find out the Pin identification for this board? (PSon, BLon, GND, etc)

I did find a table for board MLT666T (My board in MLT666FL) which has a similar layout that further identifies the pin outs. It is attached. (Pin identification table.jpg and Pin identification-rev.jpg )

Based on that info:
standby/plugged in but off

Pin-CON4
Pin 1, 2 GND +5V +5VSB +12VDC RETURN --->0 VDC
Pin 3, 4 +5V +5VDC OUTPUT --->0 VDC
Pin 5 STB SMPS ON/OFF CONTROL(ON = HIGH) --->4.55 VDC
Pin 6 +5VSB STANDBY(+5.0VDC) OUTPUT --->5.24 VDC
Pin 7, 8 +5V +5VDC OUTPUT --->0.02 VDC
Pin 9,10,11 GND +5V +5VSB +12VDC RETURN --->0 VDC
Pin 12,13 +12V +12VDC OUTPUT --->0 VDC

Pin-CON3
Pin 1,2 Vaudio +24VDC OUTPUT ---->0 VDC
Pin 3,4 GND +24VDC RETURN ---->0 VDC

Pin-CON5
Pin 1,2,3,4 +V1 +24VDC OUTPUT ---->0 VDC
Pin 5,6,7,8 GND +24VDC RETURN ---->0 VDC

Does this help?

Again, thanks in advance.

So you do have stby 5V and PS-ON to turn on the rest of the power supply but they are not on at this point. You will need to do more in-depth troublshooting down to component level at this point.
How much time do you want to spend to fix this board? Do you have tools to do SMD repair?

[ellisol]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

No I don't have tools to do SMD repair. I do have a good adjustable soldering iron and have replaced capacitors on another big screen TV power board successfully.

I was hoping for an easy fix like swelled cap or a blown fuse. I was also hopeful someone else had a similar problem with this board which could offer advise.

From the info I have provided so far does it point to the power board being bad? If so I could just buy a replacement.

Thanks

[CapLeaker]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

sounds like there is a problem with your power supply board.

[ellisol]

Re: Sceptre 40" TV X405BV-FMD8HM07 - No power

Thanks for all the help. I purchased a good used power board.