TV repair

DeeInKY

Well-Known Member
Thread Starter
Anyone try soldering any capacitors on tv boards?

My 11 year old Samsung appears to be on the way out. After some online sleuthing, it appears that the problem is in the main video board. It appears easy enough to change out. The alternative would be replacing any bum capacitors and trying that. With the age of the tv, most of the available parts are rebuilt. A new one (if you can get it.) is $340 with a small rebate when you return the bad board. I have replaced boards in PCs and this seems no harder. With the price of new parts so high, I just bought a new one of the same size (32 in.) with higher resolution for $270.
 

Rudy

ᕦ(ò_óˇ)ᕤ
Staff member
Site Admin
Electrolytic capacitors are the weak point of any electronics circuit. They are notorious for a short lifespan--they break down and drift far enough off in value that it makes the circuit inoperative. In fact, that is a running joke at an audio forum I sometimes visit--a lot of the guys refurbish old electronics and the first thing they replace is the capacitors. And the joke goes that if they buy something like a clock radio or electric stove, their first impulse is to want to recap it. :laugh:

And I've done it myself. One of my preamps (Hafler DH-101) had a capacitor go bad in the power supply. I had replaced it, but many years later the same capacitor went bad. Since I built it in 1982 ("built" for the Hafler meant the circuit boards were already stuffed, but all the mechanical assembly and wiring needed to be done), the capacitors were about 33 years old when I decided to go through the whole thing and replace them all. It actually did sound a little cleaner (less noise) and a bit more musical. The only thing I did was change the values in the power supply--I went up to the next highest voltage rating, and also increased the capacitance rating so it would have a little more reserve to it.

Come to think of it, my desktop tube amplifier (the TubeCube|7) quit working, and sure enough, it was the capacitors. This particular one was built with a bunch of off-brand Chinese capacitors, and nearly all of them measured at the very lowest end of the tolerance (which is ±20%). I found one in particular that was >30% too low. I replaced them all with premium Nichicon capacitors, and it fired right up. I also modded a couple of the values per some recommendations I had read about, but didn't notice much of a change in the sound.

The problem with a television is that the majority of the parts are surface mount devices, so unless I had the eyesight and steady hands of 30 years ago, working on those would be impossible. The capacitors, though, still may be large enough to deal with, as some of those have to be suitably large to get the capacitance and voltage values they need. It's one of those things where I might putz around with it, but there's also a good chance the problem could be something else.

The new TVs today are disarmingly cheap, even for 4K. Back in December, our LG 43-inch 43UK6090PUA was only $269.99, with a $20 discount for using Google Express at checkout. Even the 65" I bought a few weeks prior was very inexpensive compared to what they were many years ago. Sure I would have liked an OLED, but since it's primarily used for video games and the occasional YouTube channel, and as a display for my Roon player, I don't really need anything too fancy.

It does not make the greatest computer monitor, however--since it is 4K resolution, everything on it is very tiny. I would have to sit about twelve inches away to see anything. I had to set Win10 to almost 200% magnification to make it look a normal size. Although I had an idea where I could mount perhaps a 70" 4K on the wall in front of my computer desk, and use it as one gigantic monitor. 😁

My only regret is that I still have a couple of old CRT TVs in the basement, and one in the kiddo's room, and I hate to have to toss them in the landfill when they are working perfectly fine. The Salivation Army won't take them anymore--they have a glut of them in the stores that don't sell. I even have an early 70s MGA (Mitsubishi) and a mid 60s black and white MGA that a retro collector might want, yet, no interest from anyone.
 

DeeInKY

Well-Known Member
Thread Starter
Got a TV at mom’s that is 40 years old (as best as I can figure) it’s on a digital converter box and still working.

The tv repair videos I found recommended upping the voltage setting also and using stronger capacitors. Seems that there are usually only 3 boards in most TVs - power supply, main video, and Smart TV. The Smart TV board can be disconnected for a problem there and not replaced if you don’t care about the Smart TV functions. I agree it could be fun to mess with.

I hesitated due to my vision being weak and the cost of a brand new unit. I’m extremely nearsighted and being in the beginning stages of cataract development didn’t help.
 

Rudy

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Staff member
Site Admin
My eyesight isn't the greatest either--farsighted, and when I am soldering or working with something intricate, I actually stack two of my prescription glasses so I can see better. I have a magnifier on a stand, but it is nowhere near wide enough. I need a larger one, lit if possible.

Three boards in the TV sounds about right. And things are so automated now that entire boards need to be replaced or the entire TV replaced.

Here's an odd one. In some of the Acura MDX models, owners were finding there was a parasitic draw on the battery--it would be dead overnight. Finally, someone traced the problem to the Bluetooth module, which was not turning off with the vehicle. A DIY'er noticed that the problem was caused by bad solder joints. The solution in this case was to heat the oven to a lower temperature, and bake the board for an amount of time to reflow the solder, and that would usually fix the problem.

In the old days, we could easily see bad solder joints. The solder itself might looked cracked, or a poorly executed solder joint was "cold," where for instance, the solder would bead up on either a component lead or the circuit board (or terminal strip), and there was no actual contact with the other part since the rosin in the solder could act like an insulator. But today, with surface mount devices, we can barely see solder joints anymore--there are probably hundreds in a square inch. Reflowing can sometimes bring back a dead component if it is found the solder joints are weak.

The Mitsubishi 36" TV from my dad's was purchased in the 1990s and is still working. The only problem is that it lacks inputs for today's devices--no HDMI. Adapters can be used, but it's an additional hassle and more wires and boxes hanging off the back, and yet another power strip tucked behind the furniture.
 
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