Sharp LC-42DH77E

[Turnip]

Hi Les,

Got that Chinese tube checker, and all tubes tested OK (even that one I broke and replaced with a 40 inch with long wires) before I reassembled the screen.

Hard wired every tube to those convenient inverter feedback caps - wrapped one end around the tube clips, as wouldn't solder, then glued to keep things in place.

Didn't manage break anything on reassembly - tedius job with all those screen screws.

Thought to leave water based glue to set for some days before I try fire up.

Cowardice maybe, but genuine Sharp gives me that sinking feeling.

Later - glue set - fired up, did a total reset - OK - whew - Chris

[Kilroys]

I have never had a bad tube on the 42DH77 sets.
Well one, when I was loosen the clip from the tube and was in a hurry.
LV-347 describe the most common error, guessing it's because spring is
soft from the heat and makes poor contact.
If the set takes a long time to start, the clips look ok,
no burnt mark on the inverter, it could be LV-441.
Never loosen the inverter if you are not sure its the clips
or you will have problems with the contact.
I have had both, but most common the clips.
After changing the clips you had to clear the lamp errors.

[Turnip]

Hi Kilroys,

Like you never had a duff tube (before I broke one) but those inverter contacts are total rubbish. On replacing the inverter panel, several didn't make contact.

Wouldn't suggest new spares as they're expensive and no better than the original horrid design.

Next time won't bother dismantle the screen, just snip plastic over inverter connectors and hard wire all 18 tubes to the appropriate side of the inverter feedback caps.

Prob is - edge connectors contacts won't solder, but a good fine wire wrap with adhesive might be as good as it can get.

Done one, fingers crossed - Chris.

[Ecosse2253]

Hi guys just repaired two of these  sets and its not the lamps it's the crappy clips that  make a bad connection and arc making a hole on the inverter board , just turn down your iron so the solder doesn't  melt to liquid and solder over the inverter holes take the clips and run the iron over the the connecting point of the clips bend them up if needed reset the lamp error in the service menu and vola  set fixed hope this helps
Alwyn   

[Turnip]

Hi Alwyn,

You're right with the inverter board trouble - Prob is, clips don't solder - still suspect a hard-wire jobby is the best biz, but yet only done one - Voila - Chris.

[OldLes]

I see it is March since I last played with this set (LC-42DH77E). In spite of bodge repairs I never got beyond briefly seeing which lamps NO LONGER light.
Having read the "Shuts_down_lamp_error" pdf, next move is to put a S/C on C7558. Different location of C7558 on this set from that shown in the document. S/C link fitted, switch on set. Flashing red LED, unlike previous condition. Have they changed the "prevent shut down capacitor"? Is it a different component number in this set? Beautiful looking set, would be perfect for my living room, but I can see it being consigned back to scrap. Any comments?

[OldLes]

Maybe the last message is not very clear. I am attaching the Sharp bulletin concerning shorting C7558, which is shown on the second page. C7558 on my set is much nearer to the IC than that shown.
Of course if I had a circuit of the inverter, it could make more sense, but that seems to be absent from most circuits, so you are left in the dark.
Any suggestions welcomed.
Les.

[Turnip]

Hi Old Les,

General opinion is that the tubes are usually OK on this model but edge connectors are suspect, as can be seen by the burn marks on those plastic connectors and the burned holes in the inverter panel.

Just hard wire and do a reset - nice telly - All the best - Old Chris.

[OldLes]

Hi Turnip (sorry, Old Chris) and Kilroys. Decision already made on next step before reading your message Chris. This afternoon, another Monday, so with my pal we hauled it back onto the kitchen table. Inverter board out, up to electronics room, and remove last week's incorrect short. Of course the SM cap came out as well, so it took a good half hour before that was back to standard. After locating C7561, I managed to solder on a single strand from a thin wire to short it out. Again, quite a time consuming task. I worked under my 10 Xs Stereo microscope, with the finest tip iron in my armoury. Glasses and Ledu for getting things ready, glasses off and microscope to do the job. I think back 25 to 30 years when I routinely replaced up to 10 diodes on some earlier Grundig CTVs, and about 5 little black 0.1 caps on their Tuner-IF boards. It would not be profitable today with these "smaller than ever" components.
But what happened? We failed to get to the "K" screen, but this time we did see ATV 54, suggesting it had been last used on analogue "commercial", before it went to standby. And about half to one third of the CCFLs not lit!
So, it is to be the front off next time, and EVERY CCFL will be re-tested, and then individually hard wired Chris's way. I think the best method will be to use enamelled copper, well scraped, and fitted in Thorn's "tie wrap" mode.
Believe it or not, I am optimistic that sometime in the near future, I will have this set in my living room. I bought my current LCD, an EVOTEL, just over three years ago (my first new set since my 22" NordMende back in 1970, and only £15 more expensive!!!), so I guess that will be packing in before to long.
Les.

[Turnip]

Hi Young Les,

Took the front off meself feeling tubes were the problem, well, it's a Sharp, and we know 'em.

Naturally they were OK of course. But go for it, I did, but was freaked with the possibilty of disaster.

Mine was a customer jobby, and the inverter hard wire did the job - Not a 'kind word' or 'refund' since.

Made the needy pound though - Old Chris.

[OldLes]

A couple of weeks ago, we had the front off, and re-checked all lamps with the Chi-tester. All OK. Rechecked the three tubes swopped out months ago, all seemed OK, so decided to re-fit them rather than leave the three shorter ones.
I then carefully wrapped each tube clip with 0.6mm silver plated copper wire (as used by my Ex for jewelry making) and then crimped it tightly. 
Soldered a short flexible lead to each pad on the inverter board.
Carefully reassembled, this time with the soldered link on the correct (I think) capacitor, C7561.
Tried switching on mains whilst holding input and vol -. Flashing amber, then continuous green, and eventually about 1 to 2 seconds of lit tubes. Spotted UTV Ch 52 on RHS, but no sign of the infamous "K". Repeated attempts seemed to be accompanied by the set cycling thro' inputs each time (DTV, the "No Radio Channels) etc.
Tried various combinations of buttons, but never a sign of the "K".
I am moving towards the decision to return it to the amenity site, but hate the idea after all this time, with such a beautiful looking set.
Les.

[Kilroys]

You had to use the power cord when switching
off and on the set to access adjustment menu, not the power button.

[downunder]

OldLes, that CCFL tester, is that the one with a longish probe, an earth clip and red/green LEDS - only have a vague memory of one that a friend of mine bought  online. First tv he checked was a Samsung. The tester read all CCFLs as good. I was somewhat dubious so I later got him to crack the panel open. What do you know, 2 tubes were out. Personally I don't trust them as they test the tubes in an inert state and it seems they tell porkies.

[OldLes]

Kilroys, Yes, tried both physically plugging in, as well as the lazier route of using mains switch at 13A socket.
We could switch off and back on again with the set's on button, seeing again briefly the Ch No or DTV etc, followed by lamps off again. Using the mains switch, at no time did we see the "K" giving use access to "stuff".
Les.

[Turnip]

Hi Young Les,

Think mentioned B4 that all those inverter to screen connectors are suspect - suggest hard wire the lot - saves time, and did the job.

Did mine only in thin plastic covered copper -

Copper is getting expensive, esp for plumbing improvements - Called in at a supplier for some yards(metres) of 14mm (half inch) - horrid - pricewise.

Sharp Inverter/Screen hard wire requires just a few Centi-whatsits, if you're nifty with the side-cutters.

Not so nifty myself, and kept snipping the ends off - but eventual success - Old Chris.