Is Scanner HP 4070 Irrepairable due to Kamikaze Transistor?
This story started when I got this HP Scanner and was told that it was rejected by HP repair center. The complaint was that it can’t be powered up.
After opening the Scanner I found just two boards. One is the power supply/main board and the other one is the inverter/high voltage board to power up the CCFL light. This Scanner comes together with a 12 volt external power adapter.
The only bad part that I found in this Scanner was just an exploded SMD transistor and a bad fuse. The SMD transistor has a marking of “NY”.
It was very hard to search for this SMD IC data. I found 9 NY SMD transistor code in the VRT-ECA semiconductor book but the size of the transistor were different from the original one which was SOT-89 package. I found this transistor to be unique and suspected it could be the customized transistor by HP.
I asked myself the following questions:
1- Why there are no other bad components in this Scanner except that burnt transistor?
2- Why HP repair center cannot repair this Scanner ?
3- Why HP repair center does not have this part?
4- Why this transitor exploded without any reason?
Here is one possible answers that I could come out with:
It could be the designer of this circuit board use a transistor that has a specific life span. This means after the expiry time the transistor itself will automatically turn bad and causing the Scanner can’t be powered On.
Note: This is just my personal opinion.
This kind of policy in designing of HP products is not new for me. I came across a Printer model 5600 that can only work with genuine HP cartridge. The reason for it is because a special IC was installed in the cartridge and if the printer can verify that IC it will begin to work otherwise it will stop working. I have to mention that the price of a pair of cartridge for black and white and color is equal to a complete set of printer. This means that each time you change the cartridges it is just like you are buying a new printer.
In the above story, since I could not find the replacement part I could not repair the Scanner.
This article was prepared for you by Mr Beh, one of our ‘Master Authors’ from Iran.
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SANDEEP SINGH
July 11, 2020 at 12:31 am
Dear Jestine Sir,
i have a hp scanjet 4070 scanner which malfunctioned after plugging in a 12 v power supply with reverse polarity.
I think the pcb has gone bad as even after changing fuse there is no initialization.
pls help me.
Regds
Sandeep
India
Jestine Yong
July 13, 2020 at 11:59 am
Hi Sandeep,
Just open up the printer and trace the fuse circuit track downstream to see if there is any bad or burnt components.
Jestine