[time-nuts] fluke.l monitor for Thunderbolt

[Randall Prentice]

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
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Steve
Sent: Monday, 6 June 2011 11:34 a.m.
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] fluke.l monitor for Thunderbolt

Thanks everyone for the advice, both on and off list.

I do see voltage transitions on P0.5 of the C8051F330D, which is pin 19
on the DIP version of the microprocessor. So it appears that the serial
data pulses are making it from the Thunderbird to the input to the
microprocessor.

However, voltage as measured from the microprocessor VDD to GND (pins 6
to 5) is 4.94VDC. The C8051F330D manufacturer's spec for VDD is 4.2VDC
"Absolute Maximum Rating." Didier's speculation seems on point . . . 
overvoltage on the microprocessor has likely damaged it.

There is a caveat: The way the iCruze is constructed has the C8051F330D
sandwiched between two PCB's and not readily visible. So I am assuming
that the microprocessor is a C8051F330D, but that is not verified (at
least not by me). Getting at the microprocessor requires desoldering the
16-pin header which connects its PCB to the display PCB.

Not sure where to go from here . . . trash can?

Steve