Toshiba 46rv350u No backlight, No picture but has sound

[vinceroger69]

Re: Toshiba 46rv350u No backlight, No picture but has sound

can you check PFC driver IC Q860A for shorts as ive read this can blow fuse f820 too

[budm]

Re: Toshiba 46rv350u No backlight, No picture but has sound

Did you download the diagrams in post #10.
You need to check for shorts:
D809
D820 PFC
Q820 PFC
Q821
Q860 SMPS

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

Give me a few to check. thanks

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

Did you download the diagrams in post #10.
You need to check for shorts:
D809
D820
Q820
Q821
Q860

yes downloaded and printed a few sections

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

D809 no short
D820 PFC no short
Q820 PFC no short
Q821 no short
Q860 SMPS some pins have continuity with each other. I have no idea if thats normal and do not know how to test this part correctly

[vinceroger69]

Re: Toshiba 46rv350u No backlight, No picture but has sound

what is the part number of the ic at q860 then we cah get a data sheet i think its a STR-Z2589 8208 if so theres a data sheet in post 14 of this thread https://www.badcaps.net/forum/showthread.php?p=661588

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

what is the part number of the ic at q860 then we cah get a data sheet

str-z2589

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

q860 PICTURE

[vinceroger69]

Re: Toshiba 46rv350u No backlight, No picture but has sound

as per budms advice in the thread ive posted the link for maybe test this

OK, the only load for that F820 fuse is that STR-Z25XX series, so the internal short may be half of the bridge drive power MOSFETs may be shorted out.
You need to check the resistance between pin 5 and pin 1 (for the upper MOSFET), then pin 1 and pin 21 for the lower MOSFET to see if one of them is shorted out or has very low resistance. Make sure you count the pin correctly.

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

pin 1 and 5 133 ohms
pin 1 and 21 14.8 m ohm

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

actually i am getting odd reading on pin 1 and 21 starts off at 7 m ohm and drops down to around 3 m ohms

[vinceroger69]

Re: Toshiba 46rv350u No backlight, No picture but has sound

my guess is ic is bad lets see what budm says before you order one and another resistor

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

my guess is ic is bad lets see what budm says before you order one and another resistor

luckily r850 didn't blow this time, I have an extra one also just incase.

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

now pin 1 and 5 read .402k ohm

[vinceroger69]

Re: Toshiba 46rv350u No backlight, No picture but has sound

maybe remove the ic and retest?

[fg42pr]

Re: Toshiba 46rv350u No backlight, No picture but has sound

I'll have to wait until my new solder sucker comes in for removal, mine just died out. I'll get back Monday or so whenever it comes in.