HP Laserjet 4000 power problems

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HP Laserjet 4000N has become a bit temperamental. Depending on it's mood, it will:

1. Switch on and work perfectly; or
2. Switch on, work perfectly for a short period (a few seconds to several hours) then, without warning, the display goes blank and all LEDs go off; or
3. Not switch on at all

It's proving difficult to troubleshoot as it's an intermittent fault.

Checked plug/fuse and swapped mains lead.

It's not overheating, and when it does switch on the fan runs for a few seconds as it's meant to whilst the printer is initialising.

After failing, cycle the mains and it may switch back on again immediately or it may take several attempts.

Anyone had any experience of these symptoms and can suggest what to check?

santer_2

Saw this

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=110&prodSeriesId=25474&prodTypeId=18972&prodSeriesId=25474&objectID=bpl07009

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Thanks. Tried a cold reboot, but no luck.

Problem appears to be electrical/electronic and getting progressively worse.

Following cold boot, printer powered up and initialised. 3 mins later a very feint *click* and display/LEDs went off. Cycled power a few times - nothing, then it switched on, got part-way through initialising and dropped power again.

santer_2

If you click the for lbrty.com at the top of the page

http://www.google.co.uk/search?q=HP+Laserjet+4000+service+manaual&ie=utf-8&oe=utf-8&aq=t&rls=Palemoon:en-USofficial&client=firefox-a

You get the service manual

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Thanks.

Already have a service manual. Have spent the afternoon dismantling and re-assembling it. Tried using the trouble-shooting steps relating to power issues, but none of them deal with intermittent loss of power.

At one point I thought I'd narrowed it down to the formatter, as with it attached it would fail, with it removed the printer would power on and stay powered on (although couldn't be used due to formatter not present!) So I stripped and cleaned all the contacts and sockets etc on the formatter PCB. Put it back together and reattached it to printer and it ran for 30 mins then failed. Removed it again it ran for 3 mins then failed.

santer_2

Odd one

Suppose HP will only want to sell a new one.

Has it got any easy to get at internal fuses

If the internal wiring is sound, has anything happened to the power lead, power socket?

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Two internal fuses, both sound. Power lead swapped, Mains clean.

russell_e

It sounds terminal, how old is this now? 15 years?

santer_2

They may provide an answer

http://h50203.www5.hp.com/mailweb/customer/EmailForm.aspx?cc=us&lang=en&sni=35637&lang=en&cc=us

Or

http://h30434.www3.hp.com/t5/Printers-and-All-In-Ones/ct-p/InkJet

http://h30499.www3.hp.com/t5/Multifunction-and-All-in-One/bd-p/bsc-420

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Manufactured in 2002, so it's 10 years old. Hasn't exactly had a hard life, only 7900 pages from new.

russell_e

Our 4000 series printers started to drop like flies at 10 years.

HP won't help as it's old!!