Author Topic: Faulty parts Dell Optiplex 780 SFF Power Supply  (Read 486 times)

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Offline tedge

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Faulty parts Dell Optiplex 780 SFF Power Supply
« on: November 29, 2019, 09:53:27 pm »
Faulty parts Dell Optiplex 780 SFF Power Supply
I have been looking for several weeks for circuit diagram. Model H235P-00.   P/N:HP-D2352A0 Power Supply 235W. I wonder if anyone knows where I can find a schematic.
Many thanks to spilihps for the question. The link to the diagram in the forum is helpful but I cannot read the part values and number on the circuit board and would be very grateful for a diagram at higher resolution.
These are the faulty chips so far found.
(a)     Fuse F 6.3A  250V    370
(b)     ST W7NK90Z  CC OPC VW MAR825
(c)     23NM60N GK03P V3 CHN 939
My second  780 SFF Power Supply PSU
(d)  TNY280PN  K818 54478A   top of chip blown out.

Third 780 SFF Power Supply PSU. Need circuit diagram for
Dell P/N: R224M  P/N PS-5231-5DF1-LF   235

Over a period of time failed post on a number of occasions.
With Error codes looked like motherboard problems.
Proved mother board was OK by using standard ATX
PSU with a PWR adapter cable bought on Ebay for about £1.48 (Ebay item 143402320070).
The Dell Optilplex 780 motherboard has smaller PSU connector.

Parts ordered on Ebay 29/11/2019 (ebay item number in brackets)  most items from China
Ordered 5pcs STW9NK90Z W9NK90Z N-CHANNEL 900V 1.1W 8A MOSFET TO-247 ( 172821066742 ) £4.33.
 The original ST W7NK90Z  was too expensive

5pcs F23NM60N TO-220F new
( 123324260374 )

TNY280PN TNY280 DIP7 Integrated Circuit from Power Integrations £2.40

ATX PSU Standard 24Pin Female to Mini 24P Male Internal Power Adapter
Converter Cable For DELL 780 980 760 960 PC £1.48 (Ebay item 143402320070)

2x 5A Radial PCB Quick Fast Blow Circular Fuse
( 283561064019 ) £2.25

Regards Tony Edge

« Last Edit: November 29, 2019, 11:24:13 pm by tedge »

Offline KaneTW

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Re: Faulty parts Dell Optiplex 780 SFF Power Supply
« Reply #1 on: November 29, 2019, 10:01:45 pm »
Is there any reason to repair it instead of replacing it? SFF PSUs are dime a dozen.

Offline tedge

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Re: Faulty parts Dell Optiplex 780 SFF Power Supply
« Reply #2 on: November 29, 2019, 10:28:13 pm »
I bought a second hand SFF PSU.  But it was cheaper to buy a used  Dell Optiplex 780 last one I bought cost £15.  My family like the Small Footprint computers and work well with Windows
7 Ultimate 64  four of the computers are using dual monitors. We don't like Windows 10 and old hardware the performance is abysmal.   1tb Disk 4gig of Ram. We like the ESATA socket at the back of the computer.  Between us we have 8 Dell Optiplex 780s if they crash the system I can cloan a rebuild in 30 minutes with Cloanzilla from a memory stick without even having to remove the covers and use a small psu for the external Esata disk.
I would like to repair the 3 faulty PSUs to keep as spares.
I don't normally repair ATX PSUs they are so cheap and easy to buy.  Its a different matter for the Dells SFF.
Regards Tony

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