[time-nuts] Thunderbolt serial port problem UPDATE

Arthur Dent golgarfrincham at yahoo.com
Thu Apr 14 16:04:47 UTC 2011


 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.  

          -Arthur 


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