Haier L26B1120

[kf4rca]

This latest roadside find was totally dead. Haier is a Brandsmart brand. Its a 26 inch CCFL built in 2011. The fuses and caps all checked good but an FET was shorted. It was an AP4511GH which is a surface mount TO-220 style on the bottom side of the circuit board. That's an unusual FET in that its really 2 FETs in one package, an N-channel and a P-channel. It was unobtainable stateside but I found 2 for $5 out of China on Ebay. It was an easy repair if you're careful.

[timmy]

Sometimes a zener will go bad and take out mosfets it’s rare I feel that a mosfet would just short for no reason unless something else is going or maybe a defect.

[JohnCT]

Originally Posted by timmy

Sometimes a zener will go bad and take out mosfets it’s rare I feel that a mosfet would just short for no reason unless something else is going or maybe a defect.

Nah, very common. I buy mosfets for late model Samsung QLED power supplies in bulk and have at least 10 other varieties of mosfets both in both TTH and SMD for other power supplies.

With any luck, all it will need is the mosfet, but sometimes you lose the gate driver as well.

John

[timmy]

Originally Posted by JohnCT

Nah, very common. I buy mosfets for late model Samsung QLED power supplies in bulk and have at least 10 other varieties of mosfets both in both TTH and SMD for other power supplies.

With any luck, all it will need is the mosfet, but sometimes you lose the gate driver as well.

John

A lot of these throw away flat panels is diodes and zeners are not rated high enough and they short and take out the mosfet.

[JohnCT]

Originally Posted by timmy

A lot of these throw away flat panels is diodes and zeners are not rated high enough and they short and take out the mosfet.

Funais are about the only ones I've seen do that in the last 20 years. Other than those, most mosfets just fail with no collateral damage.

John

[timmy]

Originally Posted by JohnCT

Funais are about the only ones I've seen do that in the last 20 years. Other than those, most mosfets just fail with no collateral damage.

John

I have an Emerson was only a year old needed a mosfet resistor zener silicon diode because the rating was not up to what it should have been a kit was sold for that tv with all the parts.

[kf4rca]

My first experience with FET's was at a station in SC. They had a TK27 film chain. One day it lost the luma channel. I had no clue, but the asst CE knew exactly what it was. The FET preamp blew out on the luma channel. It was mounted right up there on the target ring of the pickup tube. He said they just blow out every couple of years.
Static can take out an FET. There's a great deal of concern about a high altitude EMP blast taking out almost everything electronic!

[JohnCT]

Originally Posted by timmy

I have an Emerson was only a year old needed a mosfet resistor zener silicon diode because the rating was not up to what it should have been a kit was sold for that tv with all the parts.

Yep, one of the Funai brands - Emerson, Sylvania, Magnavox, Symphonic, and Philips. There might have been some house brands but I'm not sure of that.

I did a lot of those when smaller size TVs were worth repairing.

John