Would this be safe?

[SluggerB]

I am trying to fix a broken plasma TV by replacing a large cap on the power board. It is a 1900uf 220v cap and I could only find one place that sells them. It was listed as through hole, so I bought it. It showed up today, but instead of through hole, it has spade connectors.


Would it be safe to get some heavy duty wire (like lamp cord wire), connect that to spade connectors, connect them to the spades on the cap, and run the other ends of the wire 2-3 inches to the holes and then through the holes and solder them in place? I actually did it already and put it together but I am scared to turn it on lol. Here's a picture.




Would the TV be safe to operate like this?

[R_J]

It should be fine, since you zip tied it to the board, just make sure none of the jumper wires (w76,w73) under it don't short to the caps can over time. the extra wire on the cap should not cause any problems.
This the VS filter cap, are you sure this was your problem?

[SluggerB]

It should be fine, since you zip tied it to the board, just make sure none of the jumper wires (w76,w73) under it don't short to the caps can over time. the extra wire on the cap should not cause any problems.
This the VS filter cap, are you sure this was your problem?

Funny you mention that, I found the guts to turn it on, and the TV had the same problem. I then tested the original cap out of circuit an it tests OK. So I'm just going to put it back. I guess even though it looks a little swollen it actually isn't bad.

Backstory on the TV - I was watching TV when there was a huge lighting strike nearby my house that shook the house. When that happened, the picture on the TV froze and the TV wouldn't turn off except by pulling the power cable. Now if you plug in the Tv, it seems to turn on, but there is no picture, although I can see the back light around the edges. And now the TV doesn't respond to the power button on the remote to turn off, and doesn't respond to the power button to turn off, it only turns off by pulling the power cord

Odd thing is, the TV was plugged into a surge protector, and literally zero other things in the house had any damage whatsoever. The clock on the microwave didn't even reset. This TV is the only thing that got damaged.

Since there was a picture on the screen when it froze, I know the screen is still good, and it does seem to "turn on" so the power board seems to be working, so Youtube is telling me it is probably the main board. I opened the TV up and nothing on the main board looks out of sorts, no blown chips, no scorch marks or burn marks or anything, but I ordered a used board off eBay anyway and it will be here tomorrow, hopefully that fixes it.

[R_J]

It is possible the close lightning strike damaged the microprocessor data on the main board, you could try...

[momaka]

First, to answer the question in the topic (even though it turned out this cap wasn't the issue)... I would rate this as "safe", but *not* a good practice.
For starters, the cap is now placed right above a vertical heatsink, which means this cap will get even hotter than before... and I suspect the slight bulging you see on it is from too much heat (or possibly too much ripple current from the circuit, heating the cap internally.) So any extra heat for that cap would not be a good thing long term. Also, the long wires will increase the impedance to the cap - probably not enough to cause any issues in terms of the circuit functioning, but nevertheless worth mentioning. Long wires act like antennas too. So any HF noise on that circuit will raise the noise floor to nearby circuits as well. Again, this probably won't cause any issues for a plasma TV circuit like this... but key word here is *probably*.

As for mounting caps with spade terminals like this in place where the PCB was designed for through-hole: if the PCB is single or dual layer only and the traces underneath can accommodate a cut in the PCB to make the spade terminals of the new cap fit, then you can just drill out / cut out / widen the holes for the new cap. Then just solder the cap like any other.

I then tested the original cap out of circuit an it tests OK. So I'm just going to put it back. I guess even though it looks a little swollen it actually isn't bad.

I dismantled a fairly recent Panasonic plasma (or was it a Sony, I can't remember) about two years ago (cracked/broken screen) and it had several high-voltage caps on the VS lineslightly bulged exactly like this but still reading *reasonably* in spec (though one of the caps was close to being -20% on the capacitance). Can't remember if they were Nichicon or UCC or Rubycon, but they were good quality Japanese caps. Right next to those caps I could see the board was slightly darker from nearby heatsink. So if your TV is anything like that, I suspect the bulging on these caps is caused by either (or both) of these things: the TV runs very hot, and that along with whatever heat is generated from the ripple current that these caps see makes then run very hot internally - probably right up to their rated acceptable limits.

If you do get the TV fixed with the new board, see if there are any extra free cap spots on that rail to add more caps to help ease off the load on that single 220V 1900 uF cap. Maybe cap spot C613? In addition... or alternatively, you can add several PP film caps in parallel to that big cap to help take on some of the high-frequency ripple current from the circuit. 400V 1 uF and up would be a good addition... though even several 100 to 470 nF caps would be OK.

Backstory on the TV - I was watching TV when there was a huge lighting strike nearby my house that shook the house. When that happened, the picture on the TV froze and the TV wouldn't turn off except by pulling the power cable. Now if you plug in the Tv, it seems to turn on, but there is no picture, although I can see the back light around the edges. And now the TV doesn't respond to the power button on the remote to turn off, and doesn't respond to the power button to turn off, it only turns off by pulling the power cord

Odd thing is, the TV was plugged into a surge protector, and literally zero other things in the house had any damage whatsoever. The clock on the microwave didn't even reset. This TV is the only thing that got damaged.

Since there was a picture on the screen when it froze, I know the screen is still good, and it does seem to "turn on" so the power board seems to be working, so Youtube is telling me it is probably the main board. I opened the TV up and nothing on the main board looks out of sorts, no blown chips, no scorch marks or burn marks or anything, but I ordered a used board off eBay anyway and it will be here tomorrow, hopefully that fixes it.

Probably either the firmware got corrupt or some logic chip on the main board bit the dust. If you are lucky, maybe you only have a power rail regulator that's taken a dump / not working anymore, and that's the cause of the TV to not work properly.
But since you will be getting a whole new main board, I suppose this will rule all of the above out.

As for power strips with "surge protection" - those are only good from protecting from voltage spikes on the AC line, which tend to be rare anyways. Moreover, most SMPSes like those in a TV or PC are now usually rated as "wide range" input - i.e. can take anywhere from 100 to 240V AC. So the extra "protection" on the AC line is not really necessary... not to mention just about all SMPS (or at least the better quality ones) have their own MOVs so don't really benefit from an additional one.

The close-by lightning strike likely caused either a large voltage spike to appear on the coax going to your house *OR* just the large EM pulse from the lightning strike caused large voltage spikes to appear on cables connected to the TV (analog A/V calbes, HDMI, and etc.) all of which will then feed right back into their respective reference supplies through "protection" diodes. The problem is, all signal lines use protections like this, but the reference voltage supplies that are used with these signal lines aren't always equipped to handle any large voltage spikes. So when that happens, the voltage spike can go right back to the MCU or any other chip powered from the same line and kill it. A *GOOD* design will also have Zener diodes on every important internal power supply on the main board to prevent this from happening... but most don't, unfortunately. So that's what often leads to either dead MCU or corrupt firmware on the mainboard when a nearby lightning strikes.
In short: damage from nearby lightning strike rarely comes from the AC line input and more often from EM pulses generated on external cables of any signal lines.
On that note, I'm not saying one should not use surge-protecting power strips. But to think that your devices will be completely safe from lightning strikes just because you have one is a sense of false safety.

[SluggerB]

The surge protector is art of a UPS I have other things plugged into. I don;t have the TV plugged into the battery backup outlets but the other outlets are "surge protected"

I swapped the main board and got different errors and still no working TV. I did find that the STB voltage is reading 3.5v from the power board, and I believe it should be 5v, so maybe something else was damaged on the power board? I have a replacement power board on the way but won't be here till next wednesday

[SluggerB]

I may reorient the cap to be laying the other way, and shorten the leads considerably to there isn't as much wire. The new cap is a little taller than the old one so I can't stand it up like it used to be anyway

[R_J]

The 5vstb on the power supply is switched by Q161 which is controlled by IC601, the +5v on the A board originates from the power supplies +15v and is regulated by IC5400, also ic5401 supplies +9v, are you getting and sos codes from the tv?