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HP Forum Archive 08

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how to open a hp71b
Message #1 Posted by andre schroeter on 6 Apr 2002, 5:34 a.m.

how can a hp 71b be opened ? id like to clean the inside of the display window.

best regards andre schroeter

Re: how to open a hp71b
Message #2 Posted by Raymond Hellstern (Germany) on 6 Apr 2002, 7:49 a.m.,
in response to message #1 by andre schroeter


the 71B is held together by several screws on the back. One of them is inside the card reader compartment, the others should be under the rubber feet. Be careful with the PCB, because it's relatively thin.



Re: how to open a hp71b
Message #3 Posted by Julián Miranda on 6 Apr 2002, 12:04 p.m.,
in response to message #1 by andre schroeter

If you have the MoHPC CD set you can find there a book "Control the World with HP-IL" where it's described how to open a HP-71B.

HP71B - #$%!!#!$@ screwed
Message #4 Posted by doug on 7 Apr 2002, 5:21 a.m.,
in response to message #1 by andre schroeter

Hi, I posted almost the same type of question, HP71B - #$%!!#!$@ screwed, on November 08, 2001.

A number of people responded and I fully intended to thank them, but it took quiet a bit of time to find the torx tools necessary to do the job. But at least I can point you to an exact resolution. Don't waste your time on a unit that uses 1/4 inch bits, unless you need multiple sizes. If you do let me know and I will give you the model number of a really nice unit they sell. It will not however work on one of the deeply recessed torx screws on the HP71B Case. The exact tool for all latter model HP71B units I used with success was as follows:

WIHA Proturn 657/T6 x 40 Item # 95713 $4.10 a. Tip size = T6 - This is a standard blade b. Blade Length = 40mm c. Blade Diameter = 2.5mm

Some people that posted a response to my original question said that it takes a T7. While that might be true on some older units it wasn't on the latter units I have. I also wondered if there are different types of torx bits. The answer is yes.

a. TORX - Standard tapered style blades b. TORX Security - Center point hole on blades - Nipple on screws - can't push solid standard on c. TORX Plus - Straight edge blades (Vertical)

The WHIA webiste has a lot of useful information on the subject, as well as many fine products as well. I contacted them when I found the one torx screw couldn't be removed with the 1/4 inch bit. One of the employees eventually put me in touch with a designer type person that helped me find the exact tool in just a few minutes. There was also a duplicate of one size of bits with my unit.When he sent it they paid the shipping for the replacement bit, and for the new torx driver as well. Great service and resolution. They stock the units all the way down to the rare T1 in this series. But not the 1/4 version. The quality is really fine as well.

Now for the bad news. Unless the older units are different, you have to remove the PCB to get to the LCD. That requires removing the tips of the plastic stakes with the tops melted down over the PCB to hold it in place. Cheap way to build a machine. Never intended to be repaired unless you have the complete front section of the case to put all the components in. Unless you can blow compressed air and do the job you intended. Hope this helps anyway. Doug

Torx Plus: Also: - Bottom of page

============================================================ HP71B - #$%!!#!$@ screwed 8 Nov 2001 ============================================================

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