Need help Schematics of Dell optiplex 755 powersupply L275E-01

[Duranitron]

Any one has the schematics of Dell optiplex 755

power supply model number L275E-01

P/N# PS-5271-3DF1-LF

a lot of burned parts including the mosfets, fuse, relays, foil tracts and rectifier diodes etc,

thanks in advance!

[Duranitron]

Re: Need help Schematics of Dell optiplex 755 powersupply L275E-01

I already repaired the foil tracks and replacing some of the burned parts except for the thermistor board part number RT001 it shattered beyond recognition, what i have is just a piece of it SCK that is why i know it is a thermistor.

Please help me find the value of these thermistor. thanks.

[anshad]

Re: Need help Schematics of Dell optiplex 755 powersupply L275E-01

Take a Thermistor from a scrap SMPS. They act kind of like a fuse and exact model number is not important. Thermistors in all SMPS do the same job and have the same specifications.

[Duranitron]

Re: Need help Schematics of Dell optiplex 755 powersupply L275E-01

Take a Thermistor from a scrap SMPS. They act kind of like a fuse and exact model number is not important. Thermistors in all SMPS do the same job and have the same specifications.

sorry but i don't agree with that. these thermistor is paralleled to the relay switch so putting a short circuit in a relay switch renders the relay switch useless. i thinks the value is somewhere 10ohms to 30 ohms. i really need the schematics.

[Duranitron]

Re: Need help Schematics of Dell optiplex 755 powersupply L275E-01

:i already replaced the mosfet 20MN60 the 180uf 420vdc capacitor, 6.3 amps fuse, quad rectifier diode GBU810, i need to test it but these thermistor is the problem, so i put an ordinary thermistor just recently the problem is the psu will not turn off. because the thermistor is in parallel with the relay switch. any suggestion?

[Duranitron]

Re: Need help Schematics of Dell optiplex 755 powersupply L275E-01

Take a Thermistor from a scrap SMPS. They act kind of like a fuse and exact model number is not important. Thermistors in all SMPS do the same job and have the same specifications.

thanks for the suggestion mate.. i already repaired the psu placing a thermistor SCK 054. 5 ohms cold 4 amps. and the opto isolator 817B. thanks very much!

[anshad]

Re: Need help Schematics of Dell optiplex 755 powersupply L275E-01

thanks for the suggestion mate.. i already repaired the psu placing a thermistor SCK 054. 5 ohms cold 4 amps. and the opto isolator 817B. thanks very much!

Glad to know that. Someday, may help someone else who may need to fix the same model