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Sanyo DP46142 BACKLIGHT ISSUE On few seconds, flickers, off    
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Victor2184



Joined: 22 Sep 2017
Posts: 1
Location: CLE OH USA

PostPosted: Fri Sep 22, 2017 7:05 am    Post subject: Sanyo DP46142 BACKLIGHT ISSUE On few seconds, flickers, off Reply with quote

Looking for a best order to replace boards on a tv. My issue is the backlight comes on, flickers a bit, then turns off. No noises clicks or error light. standby light stays solid green, audio works, and using a flashlight i can see the picture, change menu setting etc. (dunno if this helps narrow it down, when changing a display setting like backlight or picture or contrast or any level, hitting the up or down does cause the lcd to briefly 'refresh' turn off then on again, making me think it is the power board attempting to cycle the new setting to the backlight).

I see that a culprit can often be the power board. But some repairs also suggest perhaps the backlight inverter board. I generally take the easiest first approach, and the power board is a much easier swap than the anything else. Had no problem locating a replacement. Before i order it i just wanted to make sure it is a likely culprit. Would rather not order a part i don't need if it is far more likely to be an inverter issue. If the only way to be sure is multi meter things, what is the best place(s) to ferret this out. Far as i can tell it is an LED back light, so since i get a temporary picture on boot, i doubt it is the led's themselves that are the issue.

Found the manual, for backlight trouble shooting, i THINK i actually answered my question as to what to test to figure out which board to go with 'first' Though the shorthand used is a little confusing so here's what i worked out, but wouldn't mind an expert at reading these to check my work:

First trouble shooting step for my issue (though i'm completely guessing what NG, H and L stand for?)

Check backlight:

if ok:
-Change CN17 LVDS cable plug in (as backlight is not ok let's move to "NG")

if NG: (i assume this means 'no good'?)
-Check main board - CN2 - pin 14:

if L:
-"change mainboard"

My issue is. what does H and L mean, presumably higher or lower, true or false? Earlier in the diagram they use ok and NG, so H and L with no key dunno what to assume they mean other than inferring based on the solution presented after.

Further, NO WHERE can i find in the document (added a link to the manual, maybe i'm blind?) what pin 14 on the CN2 'port' should be? The connections are:
powerboard...p802......->...Mainboard CN2
pin 15:..........Dim.......->...BL_DIM
pin 14:..........BL_ON...->...BL_EN

if H:
-"check P803 pins 1-5"

Power/B P803 - pins 1-5 - 24Vcc

As pin 15 is labeled BL_DIM i assume it just means test that there is any kinda voltage/current on pin 14, and if so, the power board is then told "send power to the Panel Backlight." And thus, if the main board is sending the turn backlight on signal, the power board should send 24Vcc down each of the 5 aforementioned pins to the "Panel BL"

I found the power board should be giving 24Vcc for the pins 1-5 to the "Panel BL"

if L:
-"change to new power board"

if H:
-"change panel"

Again H maybe means if true/L if false?? Because if the power board is getting the turn on backlight but not sending 24Vcc down each of the 5 pins, it must mean power board is faulty to this point. And if it IS sending 24Vcc down each pin then the fault lies in the BL Panel as to that point everything is getting the appropriate signals.

So, in typing all this out, i feel i've answered my question EXCEPT i still have no idea what to check in step one, the CN2 pin 14, i did find this in the wiring diagram:

CN2 pin 14 ---- "C509"---l l-----"1nF/25V/0402"-->
.....................................^...............................^
.........................capacitor symbol?............diode symbol?

as that port connects to the P802 port on the power board and the wiring labels pin 14 as ACD i looked for that listing

P802 pin 14 labeled as ACD and a "5Vcc"---W------<ACD

So am i right to assume the CN2 pin should be getting 5v?


TV
Sanyo DP46142
Power board
Sanyo / Toshiba 75017704
LED Address Driver Assy Board Unit
SSD46TA-00 LJ97-00230A

https://www.manualslib.com/products/Sanyo-Dp46142-77711.html
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PostPost subject: Advertisement

JTS1957



Joined: 21 Jan 2009
Posts: 2344
Location: Far, Far Away

PostPosted: Fri Sep 22, 2017 7:17 am    Post subject: Reply with quote

Broken link.

The requested URL /products/Sanyo-Dp46142-77711.html was not found on this server.
kuhurdler



Joined: 28 Dec 2006
Posts: 2862
Location: Overland Park, KS

PostPosted: Mon Sep 25, 2017 8:22 am    Post subject: Reply with quote

i fixed it (the link, not the TV)
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