Dell 2405FPW blown transformer?

[budm]

Re: Dell 2405FPW blown transformer?

No DCV reading when measured right between the two pins that means the OPTO is not getting the signal to turn it on so there will be no DCV to tun the PFC IC.
You should look up the spec sheet of that OPTO to understand what it is and how it works.

[ucdzombie]

Re: Dell 2405FPW blown transformer?

No DCV reading when measured right between the two pins that means the OPTO is not getting the signal to turn it on so there will be no DCV to tun the PFC IC.
You should look up the spec sheet of that OPTO to understand what it is and how it works.

Just got the data sheet and looking at it. Basically one side sends light signal and the other side receives it? I'm still trying to make sense of the data sheet. But I just don't understand, if each leg has its own voltage, how can the two legs have voltage between them?

[ucdzombie]

Re: Dell 2405FPW blown transformer?

OK Just tested pin 1 and 2 (LED side) of the OPTO on a 10k ohm scale. There's 0 ohm one way, and infinite ohm the other way (when I switched the probes). Doesn't this indicate the OPTO is bad because I'm supposed to have the same reading either way? I didn't de-solder it to run this test. Should I take it off and test it?

[budm]

Re: Dell 2405FPW blown transformer?

"OK Just tested pin 1 and 2 (LED side) of the OPTO on a 10k ohm scale."
I do not know why you are testing the resistance when I ask you to check the DCV between the two legs of that OPTO.
As I said you need to check the DCV between the two legs of the LED which is inside the Opto and you report no DCV reading between the two pin so it is not getting the command on signal to turn on the OPTO.
BTW, are you 100% sure that there is no DCV between the two pins? What scale on the meter you are using? The Voltage should be a little less than 2VDC.

BTW, on post 38:

Just checked. The pin on the left has 35v, the other one has 30v.

That indicates 5VDC drop between the two legs, so that does not make sense either, when you now say you have 0V or 1V I am not sure any more.

There's no reading at all between the two pins when power is on. But there is continuity when power is off.

(BTW correction: one pin has 7v and the other has 6v. I was reading on the wrong scale).

"I'm still trying to make sense of the data sheet. But I just don't understand, if each leg has its own voltage, how can the two legs have voltage between them?"
Just look up how to light up LED. no Voltage on the LED then the LED will not light up, just think of it as a light bulb, no Voltage then the lamp will not light up, it is that simple.
Spec sheet of the OPTO?
You also need to get Digital meter tan do diode mode testing.
Did you also replace the blown fuse?
I gave up at this point, it is getting long and we are not getting anywhere, I will let someone else take over the troubleshooting.

[ucdzombie]

Re: Dell 2405FPW blown transformer?

Budm, thank you for your help. But I just wanted to let you know that I'm not trying to complicate things here and I'm not an electrical engineer. I'm just trying to learn something and perhaps make the planet greener. So please don't get angry at me. I followed exactly what you said and tested the legs many times and there is no voltage. I can test it again. I did the resistant test just to see if the opto is ok. I don't see why this is wrong or bad. I'm merely curious and trying to provide more information and perhaps narrow the problem down. As far as the 1v difference between the two legs, it's true. I tested leg 1 in relation to the chassis ground, it's 7v, I tested leg 2 in relation to the chassis ground, it's 6v.

Again thank you and I will continue fixing it on my own.

[ucdzombie]

Re: Dell 2405FPW blown transformer?

Just a general reply and before I end this thread (since it's seemingly coming to a dead end and it's a waste of time for anyone to help). I understand that you all are doing great things by offering your expertise for free on this forum. I as a musician actually offer a lot of free work as well, such as composing free music for indy films, playing free concert for fundraising and hospitals. I understand how important it is for us to provide support for each other in a community. And I certainly encounter similarly frustrated situations like this where I try to help others, but the lack of proper communication or other reasons make it difficult for me to continue my free work. So I understand why you do/don't want to offer your helps. And it's no big deal. Thank you all anyway.

[nomoresonys]

Re: Dell 2405FPW blown transformer?

Wondering if this was ever resolved?