[Elecraft] K3 assembly issue

[KJ7SOY]

Thanks Gernot. The RF board was already assembled when I bought the unit - I didn’t do any soldering. 

I’ve spent two days going through the boards with a fine tooth comb (aka strong magnifier) and I can’t find any solder bridges or poorly seated components. I did wake up with an idea in my head at 3am though, so I have another avenue of attack to try this afternoon. 

Thanks for the suggestions everyone! I’ll post when I’ve tested my idea. 

73
-Adrian KJ7SOY


> On Feb 16, 2021, at 7:10 AM, gt-i at gmx.net wrote:
> 
> The resistance checks are meant to measure at U13 after being placed and soldered. It is not a component check, but it will check if you have done the placement and soldering of all the connected stuff correctly. IAW,  a different value could mean you did a mistake somewhere else. Visually inspect the boards, solder joints etc before you pull out the component. In case you already did it, then just test the 7808 outside of the board. Put 12V to Pin1, GND to Pin 2 and check if you get 8V at Pin 3.
> 
> Happy building,
> Gernot DF5RF
> 
>> Am 14.02.2021 um 22:32 schrieb KJ7SOY:
>> Hi everyone! I’m new to the list and to Elecraft radios and HAM in general. Thanks for bearing with me while I learn!
>> I picked up an unassembled K3 at an auction three weeks ago. It’s been sitting in a box with most of the boards sealed in their anti-static bags since 2009. I’ve hit a snag and I’m hoping someone here can help.
>> I have the rev B RF board and I’m doing the manual’s resistance tests. Voltage regulators U12 and U13 are both supposed to test at > 150 ohms. U12 passes but U13 tests at 87 ohms. This unit has never been powered up so I suspect it has to be a bad regulator. I can solder a board just fine and assemble PCB’s but I’m not overly comfortable with hardware debugging. I’ve removed the side cover and checked for loose boards, bad connections, etc. with no success. Anyone have any ideas how I should proceed? Do I just replace the regulator? Do some other debugging?
>> Thanks!
>> 73
>> -Adrian
>> KJ7SOY
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