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hp scanjet 8250 scanner

Computer Aid Posted on by

I Recently bought a scanner from ebay.

A scanjet 8250, with outo document feeder (double sided). The document feeder was said to be faulty, & there was no power supply.

For $66.00 it was a good bargain.

Getting a 31V / 2500mA power supply was something else… I eventually built my own (with some help from Jaycar).

I had a close look at the document feeder, & it wasn’t difficult to fix (someone didn’t re-assemble it properly). It worked fine for a few weeks, but one day, it just locked-up.

I pulled out the power cord & plugged it back in, but nothing happened. I dismantled it it looked like the fuse had blown… I decided to try to bypass it, & it seemed to startup ok… so i pulled out the power cord, & re-assembled it.

Then it wouldn’t work start again… I took out the main board & measured some voltages, & the board seemed to have power at various points , so the problem could be something subtle on the board (not being an electronics wiz, I don’t know what else to try).

So I now have a very nice scanner, which won’t power-up, and I’ve no idea what to do.

I’m open to any suggestions.

Update: I ended up reselling it on ebay

Comments

hp scanjet 8250 scanner — 4 Comments

  1. Hi,

    How did you bypass the fuse?? Fuses blow for a reason, generally a faulty component ie diodes, transistors or something. Shorts are very common to blow a fuse. When you bypassed it, you may have then allowed that short etc to damage something else, something criticall. Easiest way to fix is to check voltages from the power cord, to end. When you find a component that isnt allowing the current/voltage through it, its most likely broken.

    Then again, if you say your not the real electronic type, maybe get someone with a bit of experience to look at it. Or just start replacing things until you replace the right part lol.

    Otherwise, maybe you could purchase another board. Or try a diffrent power cord, something like that is possible.

    Hope that helps.

  2. I know just enough electronics to be dangerous 🙂

    I dismantled the scanner (it only has 1 electronic board, so soldering a wire to bypass the fuse was easy (although I didn’t know I was bypassing a fuse at the time :-()

    I’m thinking the power supply voltage might have been a tad too high… I’ve dropped it down by 3 volts, but its a little too late.

    I just might look for an electronics guy… thanks for the suggestion.

    A new board might not be good… I don’t think HP have any in stock in OZ… translation: big $$$

  4. sorry, I didn’t keep the details, (particularly since it eventually fried the
    scanner)

    The most expensive part was the box and the transformer, since the salesman didn’t
    know exacty how to calculate the correct voltage, so I decided to go with a variable
    transformer.

    I’m sure you will be able to find plans on the internet… just search for terms like
    “transformer”, “bridge rectifier”, capacitor, ripple,

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