Printer HP Deskjet 5552 died

[SimonSellick]

My HP Deskjet 5552 died (between uses, not whilst in use). There seems to be no power - no lights come on and the usual high-pitched whistle is absent. The external PSU is providing its 30V and I have traced this to the first PCB which contains the internal regulators. I can't make a lot of sense of the PCB because it is multilayer and populated largely with SMCs, but there are three electrolytics rated 330uF @ 6.3V which I would expect to be the smoothing caps for the logic supply. These show no stable voltage when the machine is connected to the mains. Might there be a simple VR fault? There is also a larger 470uF @ 50V cap which has a nice smooth 30.5V, so the power is at least making it on to the PCB.

If anyone has experience of repairing these devices, or can recommend anywhere else I could look for advice, I would be very grateful. Although fairly inexpensive, this is a relatively solidly-built device and has worked very well for several years, so it would be nice to fix it rather than consign it to the tip.

Thanks in advance.

 

[davenn]

I would start by looking at where the external 30V supply connects to the main board.
There are probably some fuses in that area, before or after the various voltage regulators.
They wont necessarily be glass fuses could well be very small flat SMD fuses or ones that look like 2 legged transistors (TO92 case ... like a BC548 transistor) mite have a marking like N10 or N20 on them.
Take a photo of the PSU section of the main board and see if we can help identify things for you

Dave

 

[(*steve*)]

It's also possible that your power supply produces more than one voltage and that part of it is not working.

Does the power supply have more than 2 pins in the connector to the printer?

 

[SimonSellick]

Hi both,

Thanks for the replies. The easy one first - the PSU connector has only two pins, so I am happy that all necessary power is reaching the PCB. I can't see any obvious fuses, or SMCs with an 'N' prefix - there are some 'X's though. The PCB ident has R, C, L (obvious), Q (transistor, I think), CR (thyristor? diode?) but I can't see FS. I've attached a photo of the PSU connector area topside - there are a few more SMCs on the underside but these are around a large IC, are all Rs or Cs and are probably pull-ups and deglitchers.

Simon.

 

[davenn]

Hi both,

Thanks for the replies. The easy one first - the PSU connector has only two pins, so I am happy that all necessary power is reaching the PCB. I can't see any obvious fuses, or SMCs with an 'N' prefix - there are some 'X's though. The PCB ident has R, C, L (obvious), Q (transistor, I think), CR (thyristor? diode?) but I can't see FS. I've attached a photo of the PSU connector area topside - there are a few more SMCs on the underside but these are around a large IC, are all Rs or Cs and are probably pull-ups and deglitchers.

Simon.

no fuses on there show us a bit more of the board... and what about what Steve said
does the external plugpack/PSU only have 30V or is there more than 1 voltage coming from it ? lets see the part of the main PCB where the external PSU plugs into it \

Dave

 

[SimonSellick]

Hi Dave,

Thanks again for the reply. See attached picture of the whole of the top side of the PCB. No obvious sign of a fuse that I can see. Definitely only a single supply from the power connector (It's a coaxial connector with a single inner and a single outer).

Regards,

Simon.