Resistor values needed on a Dell E153-FPf

[Vipersan]

Hi there ..I do hope someone on here can help ..
I've searched all over the internet for a schematic for this Chinese manufactured Dell monitor ..and totally drew a blank ..
The set is fitted with a single double sided pcb ..which holds invertor and psu etc..
The psu is blown in so far as :-
Dead Power FET AS27611
SWPSU chip SG6841S
Optocoupler 817C
Capacitor C857 10uf
0.39ohm resistor R859
Primary of psu
Also replaced
Double diode on secondary s/c D854

All have been replaced ..but I'm stuck as 2 resistors in the primary are burnt open circuit..but cannot read them (idents destroyed) which is why I needed a schematic
It doesn't appear to exist in the public domain ..
The 2 resistors are surface mounts ..and one (R856) is connected between pin 8 of the SG6841S and the gate of the power fet
The other presumably feedback (R861) is connected to the FET drain and the other end to pin 6 of the FET ..
After doing this much work on it ..it would be a pity to have to give up because I can't identify 2 surface mounted resistors..
Can anyone help me ?

I've attached three photos increasing in detail ..the last shows the 2 resistors ringed in yellow ...all faulty components but these have been replaced already..
rgds
Vipersan
Uk

[tom66]

Re: Resistor values needed on a Dell E153-FPf

The topmost resistor is a gate drive resistor, in the region of 10 ohms to 68 ohms. It probably wouldn't matter too much what value you used - 22 ohms is a good middle ground.

Not sure about the bottommost, perhaps some kind of input current limiting, around 1k-10k...

[Vipersan]

Re: Resistor values needed on a Dell E153-FPf

Thanks Tom ..
You could well be right ..
What is left of the indetification on the burnt s/m resistors would sort of back this up
I think its possible the numbers and lettering thats left on the Top resistor looks like 15R0

The bottom one is more difficult ..and even with an eyeglass ..the best I can do under various lights is 4 7 X
fairly confident of the 4 ...less so of the 7 ...and no idea of the last but possibly a 0 ?
but do they lable 470 ie 470 ohm ..?
Or could it be 4K7
or even 47K
using your suggestion ...possibly 4k7..
Would be nice to have them 100% correct ...as they'd be less likely to fail again ..
thanks though..
I'll give it a little time in case of other members coming up with the 'real' values ..
If not ..I'll go with what you suggest
rgds

[tom66]

Re: Resistor values needed on a Dell E153-FPf

What you need to ask yourself is why are those resistors toast. The only cause of that I can think of is the SMPS chip is bad. That might have put 325V on that resistor. In which case the MOSFET is probably also bad.

[Vipersan]

Re: Resistor values needed on a Dell E153-FPf

Yep ..I know they were bad Tom ...thats why I changed 'em ...as posted at the beginning of the thread..
Cheers m8
VS

[tom66]

Re: Resistor values needed on a Dell E153-FPf

Yep ..I know they were bad Tom ...thats why I changed 'em ...as posted at the beginning of the thread..
Cheers m8
VS

Ah I see. TL;DR (in my case not too long, too lazy... :p)

[Rtech]

Re: Resistor values needed on a Dell E153-FPf

The one nearest to the Mosfet is 15 ohms,and the other one 47 ohms...good luck

[Vipersan]

Re: Resistor values needed on a Dell E153-FPf

Many thanks RTech ..
Much as I suspected then ..
Presumably the last number on R861 is either an R or more likely a 0 ..
470 which actually makes more sense as 0 being the multiplier would indeed make it 47 Ohms
much appreciated m8
VS

[Vipersan]

Re: Resistor values needed on a Dell E153-FPf

Using the resistor values provided by RTech ...
..I completed the repair this afternoon ..
The monitor is currently fully functional and on soak test .
Much appreciated
VS

[tom66]

Re: Resistor values needed on a Dell E153-FPf

Using the resistor values provided by RTech ...
..I completed the repair this afternoon ..
The monitor is currently fully functional and on soak test .
Much appreciated
VS

Great. Seems I was wrong on the 1k-10k... enjoy your monitor.