Sharp LC-37D5U-No Sound

[jkb242]

Recently repaired this set which would not power on but had all stand-by voltages from the power board to support a start. The problem turned out to be the microprocessor on the LCD controller board to which the LED board and KEY input board are connected. I replaced the LCD Controller board.

The picture is fine and all functions appear normal--just no sound on any inputs. I heard that there was a service recall for the "no sound" problem that appears to be quite common for many sharp sets. As I understand it, the problem is caused by a shield beneath the A/V board that was installed to prevent excessive heat from the LCD panel to the audio IC.

In my case, I don't see any evidence of factory installed insulation on or near the shield that would have become dried out with age causing a short. I am told that this is indeed a chronic problem. I called Sharp who told me there is no such recall or notice.

Anyone else encounter a fix for this problem that is related to improper insulation or proximity of the shield to the IC? This board like the other boards in this set contain parts on both sides making it almost impossible to attempt diagnosis or troubleshooting as it is impossible to connect the board to the harness when it is upside down.

What appears to be a widely-known, rather simple fix, does not appear to found on this set as that problem.

Can anyone offer any input?

Thanks

[budm]

Re: Sharp LC-37D5U-No Sound

The SAGA continues but Iam sure you will solve it eventually and that is the fun part, I will need to download the service manual for this thing. By the way, if you use the Audio Line outputs Red and White RCA jacks, do you get the sound there?
I tell you one thing, this site is addictive!
I wonder if they refer to the Audio power amp IC which will run quite warm a t high volume or the sound processing IC. I have heard about the sound problem in these Sharp TV but never run into one yet with sound problem.

[jkb242]

Re: Sharp LC-37D5U-No Sound

Right, will it ever end?

I have encountered a small glitch in my efforts to connect and disconnecting the flat micro ribbon mass terminating harnesses. One of the 33 pin harness(flat lead) has become damaged. The sockets are good on both boards but the wire traces are beginning to lift off the ribbon at the end where it enters the connector at each end. What this ribbon called so I can begin looking for a source. Sharp doesn't list the ribbon, only the sockets.

To your question about the monitor jacks, I was attempting to put the boards back together and try this when I noticed this ribbon issue. Did not want to risk powering up with the ribbon looking this bad. I am attempting a repair now but that hasn't gone well thus far--but probably making it worse. This sound issue really bummed me out, I really felt I was home free yesterday. It's really difficult to do any circuit probing/testing with the limited space and doubled sided populated boards.

Thanks, hopefully you can help me identify a source for the 33 pin ribbon.

[budm]

Re: Sharp LC-37D5U-No Sound

Yes, been there, screw up on them conductor lifted off the end of the cable from inserrting/reinserting too many times, and shorted out the connectors, they are so flimsy. I do not know the source for these cable since there are so many different pitches.

[cashkennedy]

Re: Sharp LC-37D5U-No Sound

http://www.ebay.com/itm/AWM-RIBBON-F...item4aadb33794

That might work for you. Theres a 1mm pitch version on ebay also. (pitch is the distance between the center of each contact on the cable)

If you havent destroyed the contacts (theyre still attached just loose?), then you might be able to use the contact spray that budm recommended in another thread?

[jkb242]

Re: Sharp LC-37D5U-No Sound

Thanks Cashkennedy, I did not know what pitch meant and thanks for link o EBay!!

[jkb242]

Re: Sharp LC-37D5U-No Sound

Budm,

The problem begins once the friction connecting material becomes detached from the back of the connector ends. Without this backing material, two things happen, the delicate contacts can easily damaged and the ribbon won't lock in the connector friction clamp and will simply jump out of the connector when the friction clamp is closed. If the backing piece can be successfully reattached to the ribbon before the contacts are damaged, all should be OK.

I did surgery on the one suspicious harness late yesterday using a thin coat of quick-set of epoxy, this AM we'll see how the dermatology operation went.

Did you say you needed me to send you pages from the service manual for the AV board?

Thanks.

[budm]

Re: Sharp LC-37D5U-No Sound

I had some luck in th past by carefully peel off the insulation sheet on to expose the conductors, use very sharp Exacto knife, the conductors are basically being held down by the back adhesive

[jkb242]

Re: Sharp LC-37D5U-No Sound

Luckily, the surgery seemed to work but I will keep your suggestions in mind as it appears that I will be doing more disassembly in an attempt to fix this sound issue.

[vinceroger69]

Re: Sharp LC-37D5U-No Sound

is it worth doing a factory reset in the service menu just incase something been altered on the board you have put in?
LCD Sets 1.While the LCD is on, unplug the power cable.
2.Then while pressing the {INPUT} & {VOL -} buttons on the remote, plug the power cable back into the outlet.
3.When it powers up you will see a little "k" appear in brackets.
4.Then on the TV, press and hold {VOL -} & {CH -} down and release.
5.The Service Menu will be displayed.
Use {CH+} {CH -} buttons to navigate, Use {VOL+} {VOL -} buttons to adjust the value.

[jkb242]

Re: Sharp LC-37D5U-No Sound

Thanks Vinceroger69,

Is there any difference in a service mode reset and resetting using the system reset button on the back ok the set?

[vinceroger69]

Re: Sharp LC-37D5U-No Sound

not sure to be honest i have read a post somewhere they did a factory reset and solved there missing sound problem i did not know the sets had a reset button on them.

[jkb242]

Re: Sharp LC-37D5U-No Sound

Interesting, I was also told that there was a well known cause for this issue with certain Sharp sets but what was described to me as a shield shorting on the underside of the AV board does not seem to apply to this set, in fact, I could find nothing even close to a short caused by the shield touching a trace on the board.

Removing the shield completely is another fix, which I did and it did not work.

I suspect the main audio chip a TA-2402.

Thanks again.