(ask) DELL NPS305bb 3,3v sense mod no go..

[holmes222]

hi there..i'm newbie here..
i have a DELL NPS-305BB psu..and i want to ask some question..

1. i do 3,3v sense mod with 47ohm fixed resistor and 10k vr through vsense cable, but theres no voltage change from 3,3v line..any sugestion?
the VR is set for max resistance, and when decreased the voltage still constant 3,3v
2. this psu is about 3 year old..the caps is CAPXON in primary and full of TAICON in all over secondary and filtering stage..how well is this caps in the psu ??

the pic of psu is on atachment..
thanks for your attention..

[ChaoZ]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

looks like a Delta but numbered like an NPS. Built in 2004 i believed.

This particular one is sensing from +5vsb.

Delta and NPS are good PSU.

NB: I have one which needs complusory replacement of a taicon cap for start * search the forum for more clues

[holmes222]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

its a NEWTON POWER actually i guest..from the UL number are dell corporation..if its a delta, i believe the model start from DPSxxx..but this is NPSxxx..
There's a pots near the 3,3v sense cable (thin brown cable), the blue white one, if i adjust this pot, it affect in 12v and 5v line only..and another two pots near the edge (the white one) that i don't know for..

[370forlife]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

Newton is a subsidiary of delta. Essentially, newton is delta.

[holmes222]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

so..
any suggestion how can i mod the 3,3v line up to aproxx 3,5v ??
this psu is used to powered NF4 ULTRA D rig

[370forlife]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

Why? 3.5V is out of spec for the 3.3v, it will only cause damage to your motherboard.

[POM_MJ]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

He might be want to over Vdimm voltage for DDR overclocking.

the DFI's NF4 Ultra-D also has jumper to select Vdimm from 5V, then BIOS should show more options for Vdimm adjustable from 2.5V to 4.0V.

I was overclock the NF4 Ultra-D running with winbond's UTT DDR@3.7V.

[holmes222]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

@370forlife
i know sir..but i want to do it
@POM_MJ
yes you're right sir..i have UTT that do 250mhz with tightest timing that need 3,4v vdimm..i do use the jumper to get vdimm from 5v line..but the dram mosfet regulator getting so hot..to eliminate that, i want to use the jumper trick based at XS that need to overvolt the 3,3v line up to about 3,5v..
I dont know where to start over again..
Thanks b4

[shovenose]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

Put q heatsink on the regulator

[POM_MJ]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

i do use the jumper to get vdimm from 5v line..but the dram mosfet regulator getting so hot..to eliminate that, i want to use the jumper trick based at XS that need to overvolt the 3,3v line up to about 3,5v..

yes, the mosfet very hot when use vdimm from 5V. the PCB was burnt on my mobo.

try following circuit, could be usabled.


source URL

[Toasty]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

Are you testing it loaded as in connected to motherboard?

Is there a schematic or directions as to what you are trying to do?
Do you have a link we can follow to see?

Toast

[holmes222]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

@shovenose
the mosfet already had heatsink
@POM_MJ
cool..thanks for the tips sir..i will redid the sense mod tommorow..
about 1 AM in here now..
@Toasty
i check the voltage with dmm..and powering psu outside the mobo with jumper clip on ps_on and ground(green wire jumpered to black wire on 24pin connector)..
I followed the guide from here (https://www.xtremesystems.org/forums...ad.php?t=37574)
thanks again everybody..

[Toasty]

Re: (ask) DELL NPS305bb 3,3v sense mod no go..

POM_MJ's schematic is essentially what xtremesystems.org has as instructions, sans schematic, with these differences:

- there is no 1kΩ resistor in series with the pot
- the inline resistor is 47Ω, not 100Ω

Accordingly, you should see a voltage variation on the sense line to the power supply of between 3v and 3.27v. As you adjust the pot, the 3.3v should rise to compensate for the voltage decrease on the sense line. Start the pot at MAXIMUM resistance and adjust down from there. Monitor that 3.3v line carefully.

You may damage the motherboard and the 3.3 VRM with too much voltage.

Toast