Dave <db5151@[EMAIL PROTECTED]
> wrote in message
news:peednfLHm4PLXQXVnZ2dnUVZ_sDinZ2d@[EMAIL PROTECTED]
> Once upon a time someone posted that they had found something that
really
> brought out the numbers etc on otherwise difficult to read ICs.
> Unfortunately I didn't save the post, or the info in it. Anybody have
any
> ideas on what this might have been, or how to read those invisible
> numbers/letters? Some ICs are no problem, but others... I am getting
> really tired of trying to get the light just right and halfway guessing
at
> what they say.
>
> TIA,
>
> Dave
>
>
from one of my tips files, off URL below
How to read unreadable IC/transistor lettering
Yes, just like magic.
I could not read 3 of the 5 characters on a heat damaged TOP66 power
transistor.
I wondered if a sort of "brass rubbing" would work.
I just happened to have some plummer's PTFE tape to hand ( nominal 0.05 to
0.08 mm thick).
Laid a piece over the power tranny, rubbed with a finger nail, and the
missing characters
came up like magic.
As the characters remained on the PTFE, as an image , I realised you could
use this technique to read IC lettering where it is imppossible to read,
because of constrictions and inability to introduce an inspection mirror
or
even just
where you cannot get the illumination at just the right angle to read.
You need access space enough to introduce a piece of PTFE and then rub it
with the wooden end of a small artist's brush, or similar, wrapped in some
of the PTFE, so it rubs easily without dragging.
Don't rub too firmly because you want the relief print to show as clear
and
the rest of the PTFE becoming translucent rather than the original white.
Remove and read with a backlight or against something matt black. Maybe a
couple of attempts to get a clear image in all parts of the label.
May even be worth trying on reverse-engineering-proofed, rubbed off, IC
lettering. Useful for indistinct moulding logos /
lettering etc on small plastic parts, gives some contrast.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
|
