Fixing Other’s flubs

by admin on October 16, 2017

I have a 42″ LCD TV made by Olevia. Just after it finished it’s warranty period it died. I didn’t have time to devote to fixing it because of other commitments so I took it to a shop for repair. After looking it over, the owner told me it would cost $300 to fix because it needed a new main board. I agreed and it was fixed.

After having it back for a few months, it started quitting after being on for some period of time. It appeared to be heat related because if I restarted it it would quit again in less time than the first. This would continue until it would shut off within minutes of being re-started.

I’d put thermometers on the outside of the set and I’d purchased a couple of small fans to install on the power supply. I was too late. The set quit completely. There are no “user-serviceable” parts so I set about taking it apart. It is big, awkward and heavy. I laid it screen down on a carpeted work surface to keep from scratching the screen. Not sure why I did that as our 4 year old has carved several nice gouges into the face of it…

Taking it apart was fairly straight forward until I got to the four screws that, in addition to attaching the case, attached the chassis to the legs of the stand. I fought with these screws for quite some time and was unable to get one on each of the two legs out. The two that I did get out were bent, one rather dramatically. The other two screws refused to budge, how was I going to get this thing opened up? I resigned myself to the fact that I was going to have to cut the case off near the legs. While I had several options the one I chose was to use a large (85watt) soldering iron to melt the case around the legs.  It seems that the “professional” I used to repair my set was unable to get the screws to go back in properly so he just “persuaded” them.  Two of four holes in the stand were stripped out.  Drat!!

After getting the set open, I took pictures for ease of reassembly. I removed and categorized the screws. See TROUBLESHOOTING TIPS for ideas on storage. Testing quickly proved the power supply was the culprit. I searched high and low and scoured the internet for schematic diagrams. Olevia’s idea of a service manual is a joke. It is what one would expect to give to a consumer. For example:
Problem: Set won’t turn on

Possible solutions:

  • Is it plugged in?
  • Is the Master power switch turned on?
    • Replace the power supply

It doesn’t even tell you to check the fuse in the power supply! What kind of “service” manual is that? I replaced the fuse and on restoring power was greeted with a BRIGHT flash and a blackened fuse. Something was seriously wrong! I went through the supply looking at the electrolytic capacitors with my BLUE ESR meter and found no bad ones and one that I couldn’t decide if it was good or bad. I ordered a replacement capacitor from Digi-Key, I was able to get an exact replacement. When it arrived, I checked it on the ESR meter and the reading was identical to that of the one in the power supply. No interpretation required. I attempted to overdrive the power supply with my variable DC supply but my variable supply can only deliver 3 Amps which is what the unit was fused at. After loading for several minutes the only part that got warm was a diode rectifier bridge. I’ve never seen one of these go bad before so didn’t have high hopes. Upon removing it, my hunch proved correct the bridge was fine.

I tried tracing the circuit using the Blue ESR meter with no luck. I finally gave up and did a web search for a replacement power supply. I found two merchants that offered them for just under $200 but had none in stock. I went to eBay and found that one had been sold in the last 3 months for $115. I saved a search for it and waited. About 3 weeks later I was alerted to one that was up for auction. I asked the seller how he came about it and his set died just like mine did before I took it to the shop. I bid and won for $59.

I installed the new power supply and did a “smoke” test. The smoke stayed in! I turned the set off and attached a signal cable and re-applied power. It still worked. I turned it off and disconnected all the cables. Now I had to fix the stand.

The Stand

The stand is attached to the body of the set by brackets at the bottom left and right of the set. The screws are supposed to go through the case, through the bracket on the set and attach to the stand which is tapped. I hoped I could get some new screws, dress the threads in the stand and be on my way. No such luck. It turns out that the screws attaching the set to the stand were a “fine” thread pitch. Most screws in common use are “national coarse (NC)”, in fact all the other screws on the set were NC.

I went to the local hardware store which is excellent in their selection, and has knowledgeable sales people but they didn’t have any. They could special order them and I’d have them within a week or so. I checked with several other stores and finally found suitable replacements at a store that is about 13 miles and a 30+ minute drive from here. I could buy them for $0.31 a piece. I didn’t relish the idea of spending an hour in the car. Other options?

I wanted to see if I could drill and tap the stands to a larger size. Because two of the holes were partially stripped I was going to have to upsize at least 2 sizes… I ultimately decided on drilling and tapping two new holes in each leg using a larger size screw with NC threads.

After carefully measuring, drilling and tapping the holes, I was ready to start re-assembly of the set. To make assembly easier, I disassembled the stand, removing the legs from the base. I also marked each leg as I know my craftsmanship is not the greatest and although I tried, I doubt the two legs are identically fabricated. If I should need to take it apart again, it will go together a tad easier without me having to figure out left and right again. It took me about 45 minutes to drill and tap the four holes so I saved myself at least 15 minutes. (I’m sure I would have spent a bunch of extra time in the store looking at all the things they had for sale)

After attaching the legs, I finished by installing the rear cover. Lastly, I fixed the base to the legs. I got some help and lifted it back up into position in the family room.  The kids are happy again.

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