Repair help



#2

Hi all:
I have a hp-11c and a hp-25, with the 11c once I changed batteries and my calculator was dead. Until yesterday using a small 10 cents coin, sliped the sides of the coin between both sides of the battery spring clips, at the same time with the coin, then reinstalled the batteries (LR-44), and turned it on but I did not see a " Memory Clear ", "Pr Error" or similar message. What I saw is a permanet: - 8,8,8,8,8,8,8,8,8,8
user f g begin grad dmy c progm
and it turned off until removed the batteries out.

With the hp-25 I had a battery leakage and never noticed until I changed the batteries, the new radio shack batteries charged but, the calculator doesn´t work; with the battery charger conected, the display turns on all digits, varying the brightnees of the leds continously, but doesn´t works proper. I ask for help to fix these problems.

Thanks a lot .


#3

I'm sure you'll receive lots of help from more informed persons than myself. My guess for the 11C is that with the new batteries the contrast needs to be turned down. I no longer have a Voyager series, but I believe with the calculator on, press and hold the on button and press the minus button several times to keep decreasing the contrast setting to the desired level.


#4

The ON/- procedure would only clear the memory on a working Voyager. There is no way to adjust the contrast of the display on the Voyagers, but there is no need to as the constrast is always very good.

#5

Julio --


Quote:
...What I saw is a permanet: - 8,8,8,8,8,8,8,8,8,8 user f g begin grad dmy c progm and it turned off until removed the batteries out.

If I understand that correctly, all LCD display segments and annunciators showed, then you turned it off and removed the cells?

That display is the conclusion of a successful ON/X self-test. Hitting the backarrow (<-) key should display zero in the chosen or default display format.

-- KS

#6

Hello Julio,
On your hp25, please, please don't try to run it with the AC adapter connected, untill you are sure the battery pack is making good contact. The battery pack also acts as the voltage regulator when the AC adapter is connected, and without it, the calculator IC's may be damaged by excessive voltage.


I would suggest carefully cleaning the calculators battery contacts, the ends of the batteries, and the spring that connects the batteries in the battery pack (I'm assuming since you've replaced the batteries, the soldered on strap is no more). To clean, polish until shiny with a pencil eraser, then gently rub with a q-tip moistened with alchohol. I would then suggest charging the batteries out of the calculator, with a commercial ni-cad/nim-h charger, then trying it again with only the battery pack.
Let us know how it works, and best of luck.

Hal

#7

While the batteries ARE installed in the 11C, short across the stack of battery cells with a paper clip for a couple of seconds. This is mentioned in the back of some of the manuals.

#8

As hal said, be very careful when connecting a charger on the HP25. I have one whose battery contacts were so much corroded that I had to solder a small piece of electrical wire to ensure the contact between the two printboard tracks which go from the contact. Again, thoroughly clean up the contacts before connecting the charger.


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