Page 1 of 1

Diagnose HL-S7178

Posted: Mon Feb 15, 2016 1:17 pm
by bunzinthesun
I have a HL-S7178 that is gradually dying. It started about a year ago with the analog audio inputs losing gain. To get around that I switched to all HDMI inputs. About a year later, when I turned the TV on a large white rectangle appears until I cycle the source inputs and then the TV acts normally, this happens consistently. Now while watching, the screen will occasionally change to a green sparkle with vertical lines, then the TV automatically reboots to be followed by the white square. Occasionally the TV goes dark and can only be rebooted by removing AC power. I am tempted to buy a new TV, but 70" TVs are not cheap and I am really very satisfied with the HL-S7178; it seems like a large and expensive item to just toss!

A designer friend says he has had 2 computer monitors fail because the electrolytics in the power supply got old and he could tell which ones to replace by the bulging tops! He feels from this that my problems stem from a failing power supply. I haven't had the nerve to remove the back cover and peek around, but I can ohm out and replace caps and can purchase a replacement P.S. if necessary.

But I am thinking that my problems are worse that that. Fading audio channels sounds like an Audio PCB problem, boot problems sound like a Digital PCB problem. I have the skill to replace all three circuit boards for a cost considerably lower than a new TV, but not sure at this point where to purchase them. Would replacing boards be straight forward, or am I gonna have problems?

Is this TV a lost cause orphan dinosaur?

Thanks for any suggestions.

Re: Diagnose HL-S7178

Posted: Mon Mar 14, 2016 1:51 pm
by ChubbsTech

Sounds like the boards you are looking into replacing will more likely solve your issues. Although to me it sounds like the color wheel might also need replacing due to the green sparkle with vertical lines that you mention. For parts I recommend you contact Discount Merchant. Their website is Replacing these is pretty straight forward pretty much just removing the old installing the new. Obviously soldering would be necessary but other than that pretty much plug and play. A Lot of these parts are starting to get a little harder to find although Discount merchant seems to be real good at stocking a lot of these. Hope all works out for you if at all possible do leave us an update.

Best regards,

Re: Diagnose HL-S7178

Posted: Tue Mar 22, 2016 4:50 pm
by appleads
I agree--too nice a set to just toss. Although I was given one free of charge a year ago because the owner gave up trying to fix it. Color wheels for these sets are very difficult to find, although I suspect you might be able to use one from say a 61" set of similar chassis evolution. Swapping out components one by one until you achieve success can be a bit frustrating but at this point is probably your best way to go. Given the audio "clues" or behavior you mention you might start with the DVI board. Please let us know how this all turns out. There are a bunch of us trying to keep these "on the road" as it were.