[time-nuts] fluke.l monitor for Thunderbolt

Randall Prentice randall.prentice at pscconsulting.com
Mon Jun 6 22:20:01 UTC 2011

Sorry,  I didn't give credit to you Arthur.  I was following your

My post was also to the effect that it all started going again afterward
inspite of such bad treatment (Over voltage/Over heating).

The other point omitted from my post (Obvious afterward),  was that
removing the regulator means you have to power the display from 5V.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Arthur Dent
Sent: Tuesday, 7 June 2011 10:03 a.m.
To: time-nuts at febo.com
Subject: [time-nuts] fluke.l monitor for Thunderbolt

"Mine stopped the same way. I gently spread the boards apart and
unsoldered the 3 pin regulator then added a Red-LED in place of the
three links (Original circuit had three diodes) and my monitor starting
working again. So it may be recoverable.
Regards Randall"

I agree with this as a good fix and posted this back in April.

" What I have done with the displays I got from Fluke.L is lift the end
of the interface board and hold it away from the display board just
enough so I can heat and remove the 5 volt regulator and replace it with
a jumper. It might be a little easier to just lift the input and output
leads off their solder pads and leave the chip there but I removed the
chip as well. I'm supplying the display with a regulated 5 volts so
removing the regulator from the display assembly eliminates one of the
possible problem area by removing one of the heat sources from the
board. Some people have had problems with the regulator shutting down if
they supplied it with 12 volts and the chip went into thermal shutdown.

 Next I remove the 3 zero ohm resistors (that are where the 3 diodes
should have been installed to drop the 5 volts to ~3.3 volts for the
CPU) and replace them with a red LED with leads long enough so it can be
on the back side of the interface board because there wasn't enough room
between the boards for the LED I am using. I have some SMD red LEDs but
decided they might be too hard to solder between the two boards. The red
LED makes a pretty good
~1.7 volt zener diode so now I have the display powered by 5 volts and
the CPU powered by ~3.3 volts which makes it happy." 

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