Jeff Liebermann wrote in message
...
On Sat, 15 Jan 2011 21:23:48 +0000, Baron
wrote:
Yes colours have definitely become harder to read. I've used the "PTFE"
tape trick on IC's and SMD parts a number of times to read the
markings.
I often use my pocket LED flashing to provide extra illumination. It
has a built in holder, also known as my teeth.
So, what's the PTFE trick for reading IC and SMD markings? I couldn't
find anything with Google.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
In the archives of here as
TIP: How to read unreadable IC/transistor lettering
17 Dec 2007
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 plumber'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 impossible 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.
Confirmed - this time a SIL IC with
the lettering side of the IC 2 mm from a large block cap. Would have
required 3 hours taking boards apart and back together to desolder just
to read.
Used a 1mm steel rod covered with some PTFE tape for the "rubbing" and
pulling
a length of PTFE tight around the IC through the gap,
and held tight while rubbing. I urge everyone to give it
a try, so it is impressed on memory for when required in earnest,
its just like magic
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://diverse.4mg.com/index.htm