Yes, just like magic, rub the magic lantern and say abracadabra, well it is
pantomime season
..
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 it, 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 a 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.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N Cook wrote:
I could not read 3 of the 5 characters on a heat damaged TOP66
[...]I wondered if a sort of "brass rubbing" would work.
I just happened to have some plummer's PTFE tape[...]
Laid a piece over it, rubbed with a finger nail,
and the missing characters came up like magic.

Cool.
That's a lot cheaper than what I thought of when I read the Subject
line.
http://www.google.com/search?q=dead-...nt-wavelengths
http://www.google.com/images?q=dead-...engths+laputan

JeffM wrote in message
...
N Cook wrote:
I could not read 3 of the 5 characters on a heat damaged TOP66
[...]I wondered if a sort of "brass rubbing" would work.
I just happened to have some plummer's PTFE tape[...]
Laid a piece over it, rubbed with a finger nail,
and the missing characters came up like magic.

Cool.
That's a lot cheaper than what I thought of when I read the Subject
line.
http://www.google.com/search?q=dead-...nt-wavelengths

http://www.google.com/images?q=dead-...lengths+laputa
n

There is a much more impressive system using phase array Xray or MRI or
something of very high 3D resolution to read scrolls/ medieval pipe rolls
etc without unrolling them

maybe
http://www.herculaneum.ox.ac.uk/herc...archissue3.pdf
but I've not time to download it at the moment

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/