Posts: 135
Threads: 11
Joined: Jan 1970
No solvents except distilled water! And that only after you've removed the batteries for at least a week to let the capacitor discharge. You will then have to wait several days for it to dry out. As for using compressed air, those little cans shouldn't hurt, but don't use true shop-type compressor air, it's way too powerful.
Last but not least, the cost of replacing your 48 is going up. eBay prices range about $300-$400, and Samson Cables now wants $999 for new-in-box old stock units. Just before the first HP49 came out, prices for a 48 dipped to about $100 at my old college bookstore...
Posts: 37
Threads: 15
Joined: Jan 2007
A common problem, similar to your description, with the HP 48 has to do with an internal intermittant connection. Try putting some light pressure between the display and the softkey 'C' prior to depressing the 'ON' key. If this improves the situation, I have noticed someone claiming to be able to permanently repair that problem.
Good luck,
Brian
Posts: 252
Threads: 16
Joined: Aug 2005
Hi David,
I would (very strongly) advise against a "bath" in anything!
At some risk to the feel of the keys on some hp calcs
(e.g. 41) you can use CRC brand "Contact Cleaner" in minimal amounts.
It is very gentle but used on the older hp calcs like the 41 the keys lose their tactile feedback quality when the spray is applied.
As the plastic components "dry out" (rapidly!) some of this tactile feedback characteristic recovers. At least the keys then operate!
They feel a little spongy, though and don't make a clicking sound.
A small price to pay for a functional keyboard.
Never use any detergents at all (!). If you want to run a small
*risk and use ultrasonic cleaning in a fluid (I don't have access to such exotic stuff!) the only liquid to use is isopropyl alcohol.
Distilled water sounds okay, but metal can be induced to oxidize.
At least isopropanol is as inert as you are going to get.
*If liquid permeates between the LCD interconnects to a PCB, then often you will lose the display (connections).
For What Its Worth...
DW