Dell 1800FP no 5v standby.

[triplefour]

Re: Dell 1800FP no 5v standby.

the numbers are really small so i cant be sure but its something like
11NG0C2
or maybe its
11N6OC2
or maybe its
11HG0C2
or maybe its
11RGUC2 (i swear it kinda looks like that too)
but u get the idea...
i think its that first one though...maybe

[triplefour]

Re: Dell 1800FP no 5v standby.

on ICE2XS01 i get 73k ohms on pin2 and 28k ohms on pin3

[triplefour]

Re: Dell 1800FP no 5v standby.

the resistance between pin7 and pin6 on the ic i removed is 0

[budm]

Re: Dell 1800FP no 5v standby.

"0.3 would mean it is totally shorted" If I read it correctly, that is the resistance between the Negative leg and the Ground pin of the IC which is tied to to the negative leg of the cap.

[triplefour]

Re: Dell 1800FP no 5v standby.

yeah so .3 would be totally fine in that case

[triplefour]

Re: Dell 1800FP no 5v standby.

it cant be zero since even the resistance between my 2 probes touching each other isnt

[triplefour]

Re: Dell 1800FP no 5v standby.

i think he was meaning to say that if the resistance between pin6 and ground were .3 then it would be totally shorted. but that even a resistance of 3.1 is too low

[triplefour]

Re: Dell 1800FP no 5v standby.

er.. i think that is what he said actually

[triplefour]

Re: Dell 1800FP no 5v standby.

theres a fine line between not enough and too many words when describing these things...

[bammbammfran]

Re: Dell 1800FP no 5v standby.

on ICE2XS01 i get 73k ohms on pin2 and 28k ohms on pin3

these are right
but 7 to 6 is shorted out ,so it is bad
the 11n60c2 might be what killed it again

Check resistance from 6 to 7 on the board after the chip is removed

[triplefour]

Re: Dell 1800FP no 5v standby.

the resistance between 6 and 7 on the board after the chip is removed is hard to measure because it keeps climbing...up to over 1000kohms

[bammbammfran]

Re: Dell 1800FP no 5v standby.

real high resistance is good (no dead short on board at that area)
The 11n60 is probably a problem and probably cooked the ICE chip
part number SPP11N60C3IN-ND at digikey.com should work as a replacement
before removing the old one, check your resistance between the center pin and each side pin and side pin to side pin. write these down
then recheck all 3 measurements with your tester probes reversed.
then when you install the replacement- see what the differences are
since you have the ICE out now, take the measurements of the new one also with the new ice not installed yet
also check 7 to 6 resistance on the new ice before you fire it up

[budm]

Re: Dell 1800FP no 5v standby.

Check the MOSFET'Gate R/D resistor network to see if it is damaged also.

[triplefour]

Re: Dell 1800FP no 5v standby.

burning up a chip is a learning experience...guess i should have tested further up the chain before just replacing it...
im sorry i dont know what you mean by mosfet gate r/d resistor network. could you please explain. thank you!

[budm]

Re: Dell 1800FP no 5v standby.

For you to learn, trace out the connection on the Gate pin of the MOSFET to see what it is connected to and draw out the Diagram on a piece of paper, you will learn that lots of the Gate drive circuits are basically the same.

[triplefour]

Re: Dell 1800FP no 5v standby.

ok i will try that.. i have a hard time seeing where the traces go but if its for my education i will get it done. as for replacing it, i do have lots of old power supplies i could scavenge parts from. what are the odds on finding this 11n60c2 in my pile of junk?

[triplefour]

Re: Dell 1800FP no 5v standby.

ok i dont fully understand but i think it was helpful to do this. bit by bit it starts to make a little sense. but first of all, can you tell me if my interpretation of the resistor network connected to the gate pin is correct?

[triplefour]

Re: Dell 1800FP no 5v standby.

i can see that the drain draws its power from the positive leg of the main filter cap and that it flows through the source pin to the resistor network and the ICE chip and eventually back into the negative leg of the main filter cap.... but i still dont quite understand... it kinda looks like it splits up and goes back into the negative of the filter cap and also to pin4 of the ICE

[bammbammfran]

Re: Dell 1800FP no 5v standby.

pin 5 on the ice activates on the gate of the 60n11
then the 60n11 completes the circuit through the source and drain
kind of like a light switch

this system is working on switching the neutral/ return of power side
the reason you can read + power on the drain pin is because it travels through the transformers coil

a lot of time the power mosfet (in this case 60n11) shorts or leaks too much power through the gate and it gets to the controllers and damages the controller chips


so you just need to check that all the resistors in that area are showing ok resistance wise
and that the diodes are also working in the right direction drain pin of the 60n11 i

[triplefour]

Re: Dell 1800FP no 5v standby.

and i can test all of these in circuit?