Question about HP ScanJet 3970 Flatbed Scanner
Here at my workplace I have an HP Scanjet 3970 Scanner and all the connections are fine, everythings plugged in, but it's still not working and nothing lights up.
Last I used it was about 2 weeks ago and it worked just fine then. I also had our own department IT technician take a look at it and noted that "it's just burnt out."
Any suggestions as to where I can take it to get repaired at minimal cost? Please let me know as I am unable to purchase another one per my boss.
The fuse is there to protect the scanner's circuitry in the case that the 12V, 1.25A power source, the transformer, adapter, wall wart, or whatever you wish to call it, goes above the rated values. No higher or lower V or A should make it into the device in order for it to operate within its designed range and fail. Usually there is a slight surge of some sort that blows the fuse caused by a lightening strike near by, static, or any # of other possibilities. The adapter itself is usually weakened over time, rather than the source of this increase. When the adapter goes too low, the scanner will not operate properly and usually windows will stop recognizing it as a usb scanner. At this point the various scanners on the market will give various different reactions that you'll see described in other problems in this forum, but they are all related to a reduction of the input to the scanner resulting in insufficient or erroneous output signals to the computer and windows various responses. Although the fuse is the first point of protection of the scanner circuitry, it isn't needed most of the time if you use a good surge protector to prevent any extraneous voltages from getting into the adapter in the first place. In other words, the surge protector is a 'fuse' for the adaptor, and subsequently, the scanner itself. So my recommendation for those who have equipment that is normally much more difficult and expensive to repair properly, such as a soldered-in, blown fuse (which would be professionally repaired by replacing the entire circuit board rather than just the fuse), is to bypass the fuse with a piece of wire soldered between the two metal end-caps across the top; a very simple, very quick solution. Then use a good surge protector as your 'fuse' to protect the scanner's circuitry. The obvious caveat is that you are taking responsibility for disabling the protection that was originally designed into the scanner to keep the delicate circuitry from failing due to extraneous voltage surges. There is very little risk of fire, but 100% risk of having to have the very same circuit board replaced or buy a new scanner.
Posted on Jun 10, 2009
Bridge the fuse with either a piece of tin foil...ot a soldering gun would do the trick. I had the problem of the scanner not turning on with the correct power supply and everything else working correctly. My computer also didnt register the scanner and the add hardware menu didnt show that I had it connected to the computer. Thanks to the questions here, I opened my scanner up found the tiny itty ***** fuse, bridged both ends of the fuse, put the scanner back together, and it is working just fine now!! Cheers, hope this helps!
Posted on Dec 06, 2009
I just found the same thing--blown fuse that I jumpered and the scanner lit up! I also found that the back panel calls for 1.25 amps at 12 volts, while the manual says it needs @380ma. nice way to overload the circuit, HP.
Posted on Jun 12, 2008
I just found the same thing also. Used jumper cable across fuse, and scanner fired up. Sheesh. Off to Radio Shack tommorow to buy new fuses and a new power supply.
Posted on Oct 05, 2008
Hey everyone, the 12v 340mA rating is for the transparent materials adapter (TMA) not the scanner itself, as it says in the manual above the section where that spec is listed: "Note: the following specifications refer to the document lid transparent materials adapter and not the scanner."
So the 12v 1.25A rating is probably correct for the scanner, it may just be the power supplies are cheap and probably don't stay in a reasonable range.
That aside, where is the fuse located that seems to be blowing?
Posted on Jun 25, 2008
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Posted on Jun 14, 2008
Thanks txistu. I did as you suggested, and sure enough the fuse was blown (a check with a vom confirmed this). I suspect the the ac power adapter is probably not of a good quality. Besides, hp's own specs state 12v @ 340ma for this unit. The adapter that came with this unit is rated at 1200ma. It is my belief that poor power regulation was the main culprit. I am going to use another power adapter closer to hp's own specs.
Posted on Jun 05, 2008
Today I realised I have the same problem. DC power tested and 12V-OK. Unscrew the four screws and I've seen there was a fuse inside, 1.25 A 250 V; it was burnt, but it is solded to the circuit board. I'll try getting a new one and solder it, and if I can't get no one, I'll try with a wire before drop it to waste.
Posted on Apr 20, 2008
Add me to the list of people who will NEVER buy ANYTHING from HP again. Scanner worked 3 weeks ago. Upgraded OS to XP Pro from XP Home. Reinstalled software - NADA ZILCH NOTHING. Computer has no clue the damn scanner even exists. No lights, no nothing. USB port is fine, power outlet is fine. scanner is for crap. Help from HP??? Don't make me laugh. HP could care less about customers once they get your money. As far as I'm concerned HP can inhale **** through a straw.
Posted on Mar 03, 2008
Same problem here.. everythin is plugged in and the unit seems completly dead.
any news on that problem ?
Posted on Feb 14, 2008
Here at my hone I have an HP Scanjet 3970 Scanner and all the connections are fine, everythings plugged in, but it's still not working in properly.
plz suggestions me how can solved this problem?
Posted on Oct 02, 2008
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