Toshiba 42hl167 inop


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Toshiba 42hl167 inop

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jeffd
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Jun 21, 2016, 1:51 AM

Post #1 of 3 (4232 views)
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Toshiba 42hl167 inop	Can't Post

Hi, I've been trying to diagnose a inoperative Toshiba 42hl167 TV for a while with no success. I thought I had the right service manual for it but I guess I was wrong (42hl67)...

Anyway, the TV seems to do everything but display an image; It will produce audio, I can switch inputs, the remote seems to work, I attempted to update the firmware since that seems to be a problem with these, no resolution there. Just no picture and no back light. I tried to use a LED flashlight to see an image on the screen but saw nothing.

After following the flowchart in the 42hl67 service manual I was directed to replace the Low E power board. I replaced it and saw no change. (not a surprise after realizing my error) I attempted to find a service manual online but the only places that offer them want $15-20 bucks for them... I don't have a problem paying for the manual, I just have a problem with people stealing my money- I don't trust any of the websites I visited.

I'm hoping someone on here can point me in the right direction in my diagnosis. I seem to have all the outputs from the main power supply, fuse is good, I'm not certain about a few of the power outputs from the power board. The output labeled POW_SIG provides 3.2v when the power is switched on -I would have thought this would be either 5v or 12v.

Help please!

jeffd
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Jun 22, 2016, 9:01 PM

Post #2 of 3 (4195 views)
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Re: [jeffd] Toshiba 42hl167 inop [In reply to]	Can't Post

OK, so after looking online for hours there are no service manuals available, Toshiba must not want people tampering with their TV's. I began observing how this TV operates.

The power supply obviously converts AC house current to various DC outputs. The backlighting is powered by the power supply but not activated by just turning the TV on, remember this for later... The Low-e power board is also powered by the power supply and powers the tuner board and the Sine board. The Sine board processes video inputs into a signal that is sent to the T-con board.

The T-con board is responsible for converting the signal from the Sine board into a picture using the LCD. BUT in this particular model it is also responsible for activating the Backlights. So while the backlight unit is being supplied 24v on all circuits they are not being activated, not until the T-con board interprets a valid signal.

So here we are: I have power, sound and can change inputs, volume and can update the firmware. This proves to me that my power supply ,Low-e board and Tuner are working properly leaving only the Sine board and the T-con. I'm fairly certain that the Sine board is working since It indicates All systems go and no flash codes, I can update firmware ect. So unless the Sine board is not producing a proper signal I'm suspecting the T-con. I have ordered a known good working unit and I'll report back with my findings.

jeffd
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Jul 2, 2016, 4:43 AM

Post #3 of 3 (4136 views)
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Re: [jeffd] Toshiba 42hl167 inop [In reply to]	Can't Post

Sure enough, The T-con board fixed the problem! I hope this thread helps others, I found that info for this TV was very limited.

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