Power surge blew my TV

[ckeays]

Hello everyone,

Yesterday the wind was very strong here and we experienced some brownouts. It only happened twice. The second time the light went dim in the room I was in and continued to flicker for about two seconds.

I then heard a very loud bang from upstairs. I went to check it out and the TV didn't turn on. It was connected to a (cheap) Belkin surge protector (which did absolutely nothing by the way). When this happened, two of the breakers on our main panel were tripped.

We live in a rural area in Ontario Canada, where the power lines are affected by high winds because of the trees adjacent to the power lines (among other things). Because of this, I have installed an APC UPS on everything of value. Everything else is controlled by a switched power bar or a switched surge protector. The power bar is turned off when the device is not in use. This eliminates the possibility of problems.

The one time, my son left it on and this is what happened. The TV contains only one board. I looked at the board and it is black in the power supply area. Some components have been burned. If a new fuse is installed, it just blows immediately. I have uploaded a photo of the damaged area of the board.

I am wondering what I can do about this, any advice?

I am thinking of going after the power company. They charge ridiculous "retirement fees" and other added fees to the electricity bill every month. The government just lets this happen.

I think they should be responsible for replacing the damaged TV.

 

[MrAl]

Hi,

Looks like the high voltage section, although those resistors could have been hot during the normal run of the TV so that may not be the problem area, although HV sections do go like that.

Most newer TV's have a protection circuit that shuts the unit down if there is a problem like blown HV transistor. You problem could be as simple as a blown diode in the input bridge rectifier, that would blow the fuse. If you know anything about TV's you can check the diodes, but you have to be careful in case the HV section is charged you'll get a very bad shock that could actually be deadly.
You can also check by using a light bulb like maybe 50 watts (depending on the size of the TV) in series with the TV power line to try to run it up slowly, but you should check the diodes first. Some TVs wont run up this way but it might. Before you change the diode the TV wont run up and the bulb would start to light up, but after you change the diode the TV would run up and the bulb wont light (if it's a diode or two of course).

 

[ckeays]

Both of the resistors were shorted, checking with an ohmmeter. I removed both resistors and the capacitor.

I also removed another regulator type device. I think it is shorted because all three pins are shorted when testing with an ohm meter.

I checked the diodes nearby, they all appear to be ok.

Here is a picture of the regulator type device. I don't know what this is, or even where to get one. I figure I should try and replace the components nearby. The markings on the device are:

C4450
M 7M5

 

[MrAl]

Hi again,

The package itself looks like either a transistor, regulator, FET, MOSFET, or even a dual diode or other.
How did you figure out it was a regulator?
Are you sure those resistors are shorted, or could they just be a very low value like 0.1 ohms? I ask because it's a little rare to find shorted resistors. Also possible is something in parallel with them is shorted.

Unfortunately i dont recognize that part number, maybe someone else here does.

Can you get a schematic for the TV set? Sams Photofact maybe?

 

[carbonzit]

That part is a NPN switching transistor (2SC4450). Here's the datasheet. (The Datasheet Catalog is your friend when you need to find such information.

 

[KeepItSimpleStupid]

carbonzit; We surely think similarly. A good portion of most TV problems is in the power supply.

Triplite Isobar surge suppressors come with an equipment protection warranty and it's really the only one I can reccomend. I've seen one pop too and the equipment, a computer monitor was covered. Just save the sales receipts.

In your situation, i would also invest in a "whole house" surge suppressor, again with a warranty.

 

[ckeays]

I am presently filing a claim with Belkin. I don't believe it'll get me anywhere, but I am going to try since the TV was connected to one of their surge protectors.

Also, I checked for shorts on the board where the resistors were removed, there are none.

Measuring the resistors shows a dead short on both of them, they are not low ohm resistors.

I am going to see if I can find some replacement parts here, like maybe off a PC power supply, or any other electronic equipment.

Funny thing, I was just cleaning up all my junk (old VCR's, TV's, PC's, motherboards) just crap I have been saving for years. I am going to recycle it all, but first there may be some parts I can salvage to fix the TV.

 

[KeepItSimpleStupid]

Those resistors could possibly be 5 band where silver could be a multipler. Sometimes there are three significant digits and a multipler. Metal oxide resistors usually don't short.

 

[carbonzit]

carbonzit; We surely think similarly. A good portion of most TV problems is in the power supply.

Well, yes, either that or the HOT (dunno if that's the function of that blown transistor or not).

 

[ckeays]

That part is a NPN switching transistor (2SC4450). Here's the datasheet. (The Datasheet Catalog is your friend when you need to find such information.

My apologies, I now see that the part number is C4460. It was very hard to read, even with a magnifying glass.
I downloaded the datasheet 2SC4460. The dimensions look to be exact.

I unfortunately cannot find a schematic.

I would like to replace this part. It might be the cause as all three pins, (B, C & E) all show a dead short when the transistor is removed and measured with an ohm meter.

 

[Nigel Goodwin]

I am presently filing a claim with Belkin. I don't believe it'll get me anywhere, but I am going to try since the TV was connected to one of their surge protectors.

I thought Belkin offered a guarantee for any damage, it will be interesting to see the outcome.

However, I see a fair amount of such damage (the most recent from Spain funnily enough), the electricity company is responsible, and usually pay out no problems. However, as you've messed with the set, you've probably invalidated any claim.

 

[Brevor]

Check with your electricity supplier, here in the US the power companys will pay to replace equipment damaged by power surges.