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HP CM1312nfi MFP Printer network port dead

bushtech

Sep 13, 2016
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The RJ45 network port on this printer died. No lights burning when cable plugged in.

Here's a photo of the network pcb:
Network card 1.jpg

The plug bottom left I get 3.3V on the yellow cable and 1V on the pink cable. Can't feel any chips getting hot. Pulled and reinserted all cables on board.

Now I'm stuck. What else can I check please?
 

kellys_eye

Jun 25, 2010
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Does the printer otherwise work? Are all the other ports working? Tried a new network cable?
 

kellys_eye

Jun 25, 2010
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Is the device on the other end of the network cable working ok? If it is a multi-port device (network switch for example) have you tried using a different port?
 

bushtech

Sep 13, 2016
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Thanks kellys_eye

It's plugged into a router and I've tried different ports and replaced cable. If I plug the cable into the router the relevant port's green light flashes once and then stays off. No lights come on on printers lan port
 

dave9

Mar 5, 2017
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Probably suffered a surge across the network cable. I've had a few things lose ports this way over the years, because I didn't use a surge protector on *something* in the network chain. I've never tried to repair that kind of damage at the component level, usually the device wasn't as expensive as a printer.

In this case what I'd do is get a router that has a print server function though USB, after researching whether that family of printers will work like that. I don't recall the details which make some work while some won't.
 

bushtech

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Thanks dave9.

Sadly the printer does not have a usb port.
 

kellys_eye

Jun 25, 2010
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Is the network port socket on the MFP an 'active' port (i.e. does it have the electronics built into the port itself or is it on the board?)

There is relatively high incidence of this type of (active) port going dud - maybe it doesn't have decent surge protection in it? Either way, with decent soldering skills, it is possible to replace them.
 

bushtech

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Hmm Don't know.

Here's some photos:

Port 1 (1) 1.jpg Port 1 (2)1.jpg

Says Magjack on it
 

bushtech

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@dave9: Thanks for caring enough. I might be missing the USB plot. The "USB" port on the printer looks like the RH plug on this picture:
HP USB.jpg
 

bushtech

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Thanks davenn. Now if I find a male to female usb adaptor (thought I had one) I'll try and connect wireless with a wifi dongle
 

bushtech

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Here's a link to the USB port's datasheet: //html.alldatasheet.com/html-pdf/160325/BEL/SI-80007-F/57/1/SI-80007-F.html

kellys_eye: Active?

Can I check it somehow to confirm that it's faulty?
 

kellys_eye

Jun 25, 2010
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Yup, that's a network port with the built-in isolation transformers - the actual network controller will be the tiny multi-pin chip to the left of it.

https://www.sparkfun.com/products/8534

If the transformers have blown (that's what they're there for - to protect the lines) then this may be why the port is dud. It's not 'impossible' to change the port - a real PITA if you aren't familiar with multi-layer board desoldering though.

But unless a network connection is an absolute requirement I don't know why you don't just use the USB connection?
 

bushtech

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Well, I had a look at this:
It looks possible.

But I would like to determine that it is the port before I go through the process of ordering one and replacing.

Using the USB port to connect to the router seems possible after getting the appropriate connectors/adaptors
 
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