[time-nuts] Fluke monitor

Leigh L. Klotz, Jr WA5ZNU Leigh at WA5ZNU.org
Fri Jun 4 00:46:01 EDT 2010


I fixed my fluke.l monitor.

This evening I got mail today from Bob Mokia:

    The problem is too much volts on CPU (8051F330D).
Must have  diodes 1n4148 etc at D1 and D2.  Drop cpu volts to 3.6volts.
Maximum  volts from data sheet is 4.2 volts.


D1, D2, and D3 are zero-ohm SMT resistors in series from the 5V 
regulator output.  They are visible from the CPU board edge.  Without 
removing the CPU board from the display, I was able to remove D1 and 
tack a pair of 1N4148's in series from the D1 plus pad to D2, both right 
at the board edge.  I left D2 and D3 in place.  I made the leads as 
short as possible, but still had to bend the parts up a bit to fit it in 
the case.

As soon as I plugged it in, it worked.  It's been on about 15 minutes 
now with no problems.

Leigh/WA5ZNU




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