Toshiba 55SV670U No standby light with 5 standby volts

[jhbox]

I have a Toshiba 55SV670U that I've been working on. Capacitor at r850 was blown, so I replaced it and also the voltage regulator at q880, as both going out seems to be fairly common and the parts were both cheap. I now have my 5 standby volts, but still no standby light or action on my screen. Any ideas on what I should look into next? I'm fairly new to all this.

[dskall]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.
What did you replace R850 with? Usual reason R850 goes is bad contacts on relay SR80.

[R_J]

Re: Toshiba 55SV670U No standby light with 5 standby volts

" Capacitor at r850 was blown" Do you mean RESISTOR at R850 was open? There are some small round red fuses, check them especially F840

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

@ dskall
There is only standby voltage, pushing the power button on the control panel or remote does nothing. Some of the pins were giving me a "-" on my multimeter, shown below "---"

1 - > , ---v
2 - BLANK , 0v
3 - 18v_AUDIO , .05v
4 - 18v_AUDIO , .05v
5 - BLANK , ---v
6 - GND , 0v
7 - POW_TV , 32.8v
8 - GND , ---v
9 - 12v , 0v
10 - 12v, , 0v
11 - 12v , 0v
12 - GND, ---v
13 - 5V1 , 5.04v
14 - GND , ---v



@R_J
Yes I meant resistor. All of those fuses look good

[budm]

Re: Toshiba 55SV670U No standby light with 5 standby volts

"7 - POW_TV , 32.8v " Do you mean 3.28V?
Right now something is wrong in the power supply, it is getting the command signal to turn on the rest of the power but it is not coming on.
We need good clear straight shot pictures of the top and bottom side of the power supply board.
Check the DCV between the two legs of the main filter cap when the TV is turned on.
We also need to pictures of the whole back side of the TV showing all the boards.

[R_J]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Did you check R897 (white 5watt ceramic)? when you plug this tv in do you ever here a relay click?
SJ has good pictures top & bottom

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

@budm

Yes, 3.28v. I can get you the pictures, but I can tell you that there is no damage or burns viable on the board itself. If you need pictures to reference I can dig those up off the interwebs easily enough. I don't know which capacitor is the main filter, and the TV never "turns on" per say, just has standby power. I'll get you some pictures though.

@R_J
R897 is good, and the click IS audible.

[budm]

Re: Toshiba 55SV670U No standby light with 5 standby volts

There is action on the mani board otherwise you will not have POW_TV command signal from the main board to turn on the rest of the power supplies.
There are two large main filter caps C820, 821 with 450VDC rating on them so they should have 380~400VDC between the two legs of each cap if the PFC Voltage booster is working, you must have that boosted Voltage for other power supply sections to work.
Also make sure to check these parts:
Resistors R851, R898.
Fuses F820, F880, F895
Verify that you can hear the relays SR80, SR81 click on.
"If you need pictures to reference, I can dig those up off the interwebs easily enough" We need the pictures of your board since you may not see the problem on your board but we may be able to see problems based on our experiences.

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

@budm
Perhaps this is my inexperience showing, but how can get to the pins of C820 and C821 whilst having them grounded to the panel and powered? I would have to access the bottom of the board, but it has to be screwed down for the ground.

Resistors R851 and R989 have continuity
Fuses F820, F880, and F895 have continuity.
Relays SR80 and SR81 both can be felt clicking when plugging/unplugging

I'll see about getting a picture of my board top and bottom.

[budm]

Re: Toshiba 55SV670U No standby light with 5 standby volts

If you look at the bottom side of the board then you will see that the + legs of the caps go to the fuse F820 and the negative legs of the caps go the jumper wire which means you can access those two test points from the top side of the board.
BTW, did you set the meter to 200 Ohms scale when testing the fuses? Do the readings show <1 Ohms?

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

@budm
I'll check those caps when I get home. As far as the fuses, I tested for continuity, not resistance. I'll check it out.

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

@budm
I got about 175 from F820A to JP027 JP028, and JP029.
Checked fuses again, and they all have less than 1 Ohm.

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Just noticed, the resistor that I installed int he place of the dead one at R850 is showing 2.2 Ohms instead of the 1.8 it is supposed to be doing. Could this be a part of the issue?

[budm]

Re: Toshiba 55SV670U No standby light with 5 standby volts

I will have to search the ELEKTROTANYA.COM to see if they have service manual for your TV or for your power supply board next. Right now it looks like the PFC Voltage booster is not working.
Your board has three power supplies.

[budm]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Just noticed, the resistor that I installed int he place of the dead one at R850 is showing 2.2 Ohms instead of the 1.8 it is supposed to be doing. Could this be a part of the issue?

This due to your probe resistance that gets added to the reading of the resistor, the resistor is fine, they usually go open circuit due to failed relay contacts. The R850 is for inrush current limiter and it is bypassed by the relays, so if has gone open then more likely the relay contacts are worn out, it is common failure in Toshiba power supply board.
If you search badcaps.net for 'resistor R850' will see lots of threads about that resistor and the relays.

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Was I correct in getting my reading from F820A to JP027 JP028, and JP029? Wasn't 100% sure if the JPs were the jumper wires you were referring to

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Also, while my honey-do list is keeping me from getting full pictures of the board tonight, here is a quick snap of the power and main board both mounted.

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

I couldn't help myself, chores be damned.

Pulled the covers off the relays and I was wrong. SR81 IS NOT closing. SR80 closes once plugged in and opens when unplugged.

[jhbox]

Re: Toshiba 55SV670U No standby light with 5 standby volts

@R_J
What were you getting at with the relays?

[R_J]

Re: Toshiba 55SV670U No standby light with 5 standby volts

Sr80 closes means its getting its coil voltage and is being told to turn on.
If SR80 closes, it supplies ac to D899 Bridge, You should have around 160 volts across C880. That is the circuit where you changed the regulator ic. Do you have any voltage across C898, C890 or C895?
Also do you have any dc voltage on the coil of SR81 or R853?
Its hard to trace the circuit just using a picture