How is the supply voltage? Regulator hot?
Ken VA3ABN
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On Fri, 4 Apr, 2014 6:03 PM PDT leerwolf@... wrote:
I just finished assembling the above-mentioned Softrock kit, the 20 meter version. The problem is that there's no signal--or the signal is too low amplitude--to my software. I've built a number of kits over the years, this is the first that hasn't performed upon completion. I've gone over all solder connections, checked under bright light and magnification for bridges, splashes or cold joints. I found none but I've reheated the connections to the SMDs just to be safe. I no longer have a scope (sold it when I decided to quit fixing antique radios) so about all I could test are the voltage and amperage readings as set out in the assembly instructions. All the current draws are on spec, the continuity checks through the bandpass coils are fine, and all the voltage readings are on the dot EXCEPT for pins 2, 6, 8, 9, and 12 of U2 (the Dividers, 74AC74 chip) and pins 2 & 14 of U3 (the mixers--pins 2 & 14 get their signals from U2 pins 8, 6 & 12 so it's not
surprising their readings echo the others). For the guilty pins, the expected voltage should be about 2.5 but is instead .25v. I haven't found a short to ground or a failed capacitor to explain the low readings.
So: my working assumption is that U2 is defective. If so, I'll contact WB5RVZ and see if I can order a replacement. I thought it wise to ask here first, where the well of experience is deep. Maybe I'll get a refreshing idea. Thanks for reading! Lee, WU0V.
