Re: Z-RAM ultra 2... replacing the battery?

[mjmahon@aol.com (Michael J. Mahon)]

Gary replied:

>Michael J. Mahon wrote:
>
>> That actually suggests another possibility worth trying.  Use a Q-tip
>> with some non-oily alcohol to clean the board around the chip and the
>> crystal and its loading capacitors.  (One of the loaalcoholcitors is
>> probably a small trimmer.)  Try not to get alcohol into the trimmer, since
>> it would take a while to dry.  Follow close behind with a dry Q-tip to
>> clean up whatever the alcohol may have dissolved.  The purpose of
>> this exercise is to ensure that the PC board is not contaminated with
>> a dirt-oil-flux film that might be enough to stop the oscillator.
>
>That sounds like a good first step. I did notice some general dust had
>filtered into the system when I pulled the card, but just blew it clear and
>didn't think anything more of it. I guess I'll have to scare up some
>cleaning alcohol. (I remember back in college, we stopped by a liquor store
>in a New Hampshire to buy some everclear, since it's illegal to sell it
>here in Massachusetts. We claimed at the time we were just going to use it
>for cleaning circuit boards... and perhaps the saddest thing is... that
>*is* all we used it for.) I'm assuming rubbing alcohol will leave some sort
>of residue, since it has impurities in it? Would acetone be too harsh for
>this purpose?

As Wayne notes, acetone is not recommended for PC boards!

>I do recall that there is some sort of adjustment trimmer on the board...
>I'll make sure to clean that out as best I can (using compressed air... not
>the cleaning solvent). Would it also be a good idea to note the setting of
>the trimmer, then rotate it back and forth a few times and then set it back
>to its original position? I'm thinking that there might have been some
>slight corrosion or tarnishing of the connections in that thing, which
>exercising might reduce. 

No, don't adjust it--unlike a pot, a variable capacitor is not improved
by rotation.

>>> I'm not able to discern many other
>>>relevant details from the sheet (it's been almost 20 years since I flunked
>>>my last EE class ;-). The datasheet is dated 2002, so I assume the part is
>>>still made... perhaps I could just buy another one and swap out the
>>>existing chip (I think everything on the board was socketed, so I wouldn't
>>>have to tax my limited soldering skills).
>> 
>> That is a very practical approach, though you may still need to replace
>> the crystal.
>
>That's probably a bit beyond my skills... I've not really soldered anything
>that is heat sensitive, so I'd have to get comfortable with that. In all,
>since the board functions fully as a RAM card, I may just accept the loss
>of the clock function for now.

That sounds reasonable.  A valuable PC board is not a good thing to
practice on, and a crystal least of all.  ;-)

And there's always the chance that it will simply "heal" itself...  ;-)

-michael

Check out parallel computing for 8-bit Apples on my
Home page:  http://members.aol.com/MJMahon/