HLS-7178wx/xaa challenging problem

[appleads]

Recently I was given a 72 inch Samsung DLP for free. I make a hobby out of fixing these fat old TV sets and then finding deserving people to turn them over to, usually just for the cost of parts. In this instance the set needed a new bulb. Done. But the audio volume was virtually non existent. Everything worked just fine, but no real volume out of the TV was available. I figured it had something to do with the DVI board (all that stuff on the left side of the TV) versus the center (light engine) or the right side (power supply.) So I hunted around for a replacement and found the same unit out of a 67 inch version. Since it had the same part number I bought it thinking it would solve my problems. After installing it, I'm kinda stumped. Whilst my previous DVI assembly worked well except for no volume, this unit does not. Instead, the TV keeps clicking loudly out of the power supply. Nothing about the TV has changed except for that DVI assembly being swapped out. So why am I getting this loud series of clicks out of the power supply or possibly ballast and no lamp, no screen, no nothing. They were just fine previously. I guess I will reinstall the old DVI assembly and see if the TV returns to its previous state. In which case I'll declare the replacement DVI assembly DOA and try to return it. But I wish I knew why this solution didn't work. Any thoughts from any of you who know so much more about these sets than I do????

[ChubbsTech]

Hello,



It is a little weird that now after installing the DVI board that you would suddenly get these clicks which I assume are coming from the ballast. I believe it's possible that the DVI board itself could have issues and might need a replacement. Let us know of your findings after reinstalling the old board please. I think the TV should go back to how it was previously.



Regards,

[appleads]

Well to my embarrassment I should first correct the model number. It's a HLS-7178wx/xaa although it seems to me to be nearly identical to the HL72A650. I removed the "new" unit and re-installed the old one. Works just as it did before, picture is just fine, audio has no gain. Barely audible at 100%. So now I'm wondering if I can get by with just finding and buying a new "signal board" part number BP95-00444B instead of the complete DVI assembly or "main board" assembly. Is the audio amplifier part of the signal board that stands vertically and plugs down into the main board? If so, then my main board should be good and all I need to replace will be this signal board. If I am that lucky. What say you experts?

[ChubbsTech]

Hello,



From what I was able to find out the actual audio amplifier is on the main board and not the signal board.

[appleads]

Yep, I can confirm that the audio amplifier section is on the main board, because I jumped at the opportunity to buy a "nearly correct" signal board and when I swapped it out tonight, it made no difference. When I say nearly correct, it was something like a BP95-00444A and I needed a BP95-00444B but the only difference was a "g link" or some other addition to the panel which I didn't care about. The A version worked the same as the B version I took out, so swapping out the signal board does NOT make a difference. I'll have to find a main board. Now to go back and confirm the correct part number I'm looking for and try to buy that. Unfortunately, not any around at the moment. But as these units have DMD's that fail, more and more are being scrapped and parted out. I'll just have to be patient I suppose. I thought I'd investigate the possibility of getting my board fixed, since all that's shot is the audio amplifier function. More to learn about circuit board repair I guess. And whether it's even possible or practical to get mine fixed, rather than wait for a replacement to show up.

[appleads]

Well here's an update. Still no luck finding the correct main board available for sale, but as luck would have it, the servo repair business next door says they have a great circuit board repair guy in Chicago. So my next step will be to remove the main board from the 2 sets I have that are suffering from this "no gain" condition and see if these guys can figure out what part of the circuit board is kaput and put in the correct mircrochip or whatever that is needed to fix the issue. Stay tuned as they say.

[appleads]

Well I contacted a couple of possible sources of circuit board repair and got no where. Luckily, the correct model board finally appeared on eBay. I swallowed hard and paid the $99 the seller wanted for a used main board. It came bare bones without any of the shielding etc. so I had a fun time carefully swapping everything over. I slipped it into place, got all my plugs in the right slots, put the whole thing back together and viola, I now have a perfectly functioning 72 inch Samsung set. Boy those big screens deliver quite a viewing experience. It's already been "dibbed" by one of our workers. I hated to up the price to include the cost of the replacement main board, but at $375 she's getting one helluva deal IMHO. Here's how it broke down from a cost standpoint--bought the broken unit for $150 (paid too much) put in a new lamp ($75) replaced some bulging capacitors on the power supply ($16) replaced the main board ($99) so total costs: $340. Profit from a friend $35. If I had sold it to someone else I'd have tried to get $450. As it is, I'll use the money to buy 2 new DMD chips in order to fix a couple of HLT61A750's I've got.