HP Laserjet ..again....

[Geoff Reed]

At 02:17 PM 9/18/2004, you wrote:
>As I stated earlier, I have cannibalized three HP laserjet series II 
>printers.  In looking over the parts recovered I find that I have three 
>(3) totally different memory boards.
>
>The first is populated with small chips on BOTH sides of the board with a 
>total of 128 soldered in chips that appear from their part numbers to be 
>256K memory chips,  That is the number 256 appears within the part 
>number.  Now I don't know how wide the buss is but I am assuming 8 bits 
>because of its age.  If so this board is a 4 Megabyte  memory board.

um, that sounds probable...



>The second is only half populated with 16 soldered in chips on one side 
>that have the number 1000 in their part number so I am assuming they are 
>1meg chips and using the afore mentioned logic I come up with a 
>2Megabyte  memory board.

yes, that's a 2meg board using 1 megabit chips



>The third is fully populated with 32 socketed chips with the number 1000 
>in their part number and that works out to a 4 Megabyte memory board.


yes, that is a 4 meg board.




>Is my logic sound?
>
>Do I have two 4 meg boards and a 2 meg board?
>
>What is the largest memory board the Series 2 could hold?

  4 megabyte

>I am assuming that the socketed memory is best because it is easily 
>repaired, but are there any problems with the socketed memory having bad 
>contacts after time?

the biggest problem I've had with laserjet boards is the PALs and GALs they 
used on some boards (HP and aftermarket) for addressing failing over time :(