Samsung 213T inverter

[PlainBill]

Re: Samsung 213T inverter

I am working on a couple of Samsung 213T 21" lcd panels. They do not power on. I started by recapping the psu with 6 caps that I had on hand (top 3 are NHG 1000uf 25v - {i know this is bad - FCs are on the way}). Still the power will not come on. I noted that the power supply was making a clicking sound. I probed the voltages coming out of the PSU and they were fluctuating. So I concluded that the power supply was cycling.

Exploring this idea, I unplugged the inverter board and lo and behold the clicking went away. I was then able to get a green power light to come on when I pushed the power button. I tried shining a flashlight to see if there was an image, but none was apparent.

Now I am concentrating on the inverter. I tried testing the 4 220uf caps with my cap analyzer 88a, but it showed a short. I removed the 4 caps and tried testing them out of circuit. Apparently they are completely gone because the cap analyzer doesn't recognize them. The look like they could be domed, but the glue on top makes it hard to tell.

The inverter board still shows a short between the holes for all of the caps and across the primaries of the transformer coils and pretty much the whole inverter board. I assume that this is not good. The secondaries of the transformers read 219 ohms.

Can anyone make any recommendations on what to do next? I have some new caps on order. Should I just put them in and fire it up? Or is there something else I should look at? Like lifting one side of the transformers to check them for shorts out of circuit (this is scary because everything but the 4 e-caps are SMD)? It is hard to tell, but there is some goo on each side near the blue caps and big resistors. It doesn't look it is coming from the transformers, looks more like it came from the white glue stuff.

Second picture, there are 4 'ICs' (probably FETs) in each of two columns. It appears that the 'magic smoke' has escaped from the bottom two ICs in the left column. What are the part numbers on these?

PlainBill

[bluto]

Re: Samsung 213T inverter

Well I guess I need to correct my post a little. I read some of the other posts on measuring the resistance across the primaries on some of these transformers. It looks like low resistance is the norm here. So when I said that they were shorted (ie my continuity beeper went off), I actually mean that I get 2.1 ohms across the primaries and 2.6 ohms across the capacitor pads.

[bluto]

I am working on a couple of Samsung 213T 21" lcd panels. They do not power on. I started by recapping the psu with 6 caps that I had on hand (top 3 are NHG 1000uf 25v - {i know this is bad - FCs are on the way}). Still the power will not come on. I noted that the power supply was making a clicking sound. I probed the voltages coming out of the PSU and they were fluctuating. So I concluded that the power supply was cycling.

Exploring this idea, I unplugged the inverter board and lo and behold the clicking went away. I was then able to get a green power light to come on when I pushed the power button. I tried shining a flashlight to see if there was an image, but none was apparent.

Now I am concentrating on the inverter. I tried testing the 4 220uf caps with my cap analyzer 88a, but it showed a short. I removed the 4 caps and tried testing them out of circuit. Apparently they are completely gone because the cap analyzer doesn't recognize them. The look like they could be domed, but the glue on top makes it hard to tell.

The inverter board still shows a short between the holes for all of the caps and across the primaries of the transformer coils and pretty much the whole inverter board. I assume that this is not good. The secondaries of the transformers read 219 ohms.

Can anyone make any recommendations on what to do next? I have some new caps on order. Should I just put them in and fire it up? Or is there something else I should look at? Like lifting one side of the transformers to check them for shorts out of circuit (this is scary because everything but the 4 e-caps are SMD)? It is hard to tell, but there is some goo on each side near the blue caps and big resistors. It doesn't look it is coming from the transformers, looks more like it came from the white glue stuff.