Posted by
Bill Coleman-2 on
Aug 03, 2012; 3:52am
URL: http://elecraft.85.s1.nabble.com/K2-KPA100-Failure-to-be-recognised-Troubleshooting-question-tp7560222.html
OK, my K2/100 has been operational since October 2002. Very recently, I started to get some INFO 080 errors, and then the K2 completely failed to recognize the KPA100.
Looking at it on the bench, the Vdd at Pin 1 and 20 of U1 of the KPA100 is about 1 volt. OK, if the PIC doesn't get enough voltage, it is no wonder why the K2 doesn't recognize it.
I removed the U1 chip, and the voltage rises to about 1.1 volts. U3 (the voltage regulator) is warm to the touch, which tells me it is likely current limiting.
Pulled U3 off the board and it tests just fine (although I'll replace it with a new part because now it is rather smoogly). Put an ohmmeter across the 5volt point and ground and I read 13.8 ohms. Hmm. That's in the ballpark.
SO -- it's probably either U4 - the MAX1406 or U6 - the EL5146C chip that's gone bad and is shorted out internally. I don't see any evidence of a solder bridge or flake or other issue. I suppose I'll order some replacements.
Question: Which chip should I remove first? I'm leaning toward the EL5146C, since I was getting some odd-ball power output behavior before the INFO 080 issue raised up. Plus, it has fewer pins than the MAX1406….
Any other suggestions as to why either of these chips might have failed?
Bill Coleman, AA4LR, PP-ASEL Mail:
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Web:
http://boringhamradiopart.blogspot.comQuote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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