Bill,
With that evidence, I would arbitrarily replace Z1. Those 4MHz
resonators are inexpensive.
73,
Don W3FPR
On 9/5/2018 2:42 PM, Bill Coleman wrote:
OK, a final follow-up on this.
Since the 12CTRL signal resulted in 5V power at the regulator immediately, I
racked by brain trying to figure out why The KAT100 would fail to light the
LEDs for seconds, sometimes tens of seconds.
I decided the problem might have to do with the U1 clock. I put a scope probe
on pins 13 and 14 of U1. While the KAT100 fails, these pins would float up to
about 1 volt. When it worked, these pins would be at 0 volts, because the chip
is sleeping! (the oscillator doesn’t run while the chip sleeps, to save battery
power) So, it looked very much like the oscillator wasn’t starting reliably at
power-on.
I hit the Z1 resonator with a heat gun, with no immediate effect. Later I
nudged Z1 with a screwdriver, and the KAT100 suddenly came to life. Not sure if
I had a bad device, or just a bad solder connection, I re-flowed the solder
connections to Z1 and to pins 12-14 of U1, where they connect.
This seemed to work. I let everything cool down overnight, and checked it again
in the morning. Oddly, the K2 was giving Info 080 and the KAT100 was failing
again! I didn’t have time to diagnose.
Today, however, the K2 powered right up, and the KAT100 snapped to attention,
both working flawlessly.
At the moment, I’m going to declare the mystery as being solved, and ignore the
transient Info 080 issue. If it crops up again, I think I will replace Z1 on
the KAT100.
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