On 4/13/2011 5:47 PM, [email protected] wrote:
Fluke.l is using my design except for a number of units which were shipped with
0 ohm resistors where the 3 diodes were supposed to go. This powers the CPU
with 5 V instead of 3 and most don't last long at that voltage. However, the
symptom is a blank display.
Also, I understand some units have an actual 5 V regulator and some expect a
regulated 5 V.
I have tested a total of 9 units, 2 from fluke.l one from Dan Karg and the
other are mine against 3 Thunderbolts (2 group buys and one of the original red
boxes) and they all work. As long as the serial data is enough to bias on and
off the 2N2222, it should work.
Check the wiring and check that the serial data goes to the CPU. There is not
much that can go wrong if the CPU is working.
It is possible that the serial input to the CPU is fried while the rest of the
chip works, but I have never seen that happen. Yet I have fried a number of
these chips (I design HV supplies in my day job).
Didier KO4BB
OK I think I will check the signal going to the CPU. If it is there,
then I will throw the unit away.
If the signal is not at the CPU I will trouble shoot further.
Thanks for the suggestion everybody.
Bill K7NOM
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