[Elecraft] K2 Control Board Resistance Checks

[OZ2BRN Brian Lodahl]

Hi Paul WN2K,

What I propose you do is:

1) Set the return/ground/neutral lead - typically the black lead - of 
your multimeter, to one of the grounding terminals that you soldered 
into the control board using a piece of component lead. The easiest way 
for you to do this is to use an alligator clip, preferably if your 
multimeter already is supplied with this.

2) You may wish to start with self-testing the ohm meter by itself: 
Short the two test leads and read out something around 0 ohms. Take a 
couple of resistors from your junk box, say 1k, 10k, 100k, 1M and 
measure each of them with the appropriate range. You should see your 
ohmmeter respond accordingly. Purpose of this test is to build up your 
own confidence to your test instrument measuring correctly, before you 
start measureing on your assembled control board and suspect this being 
wrong.

3) For each of the measurements you need to perform according to the 
checklist, you set the Ohmmeter's range on the closest level ABOVE this 
range. Say you need to measure U3 pin 8 to >10k ohms, and your ohmmeter 
has a 20k range, you set it to 20k. Then you probably in this case see 
the meter indicate "open", so you change to the next range - e.g. 200k 
ohms and try again. Then if still no reading, change to 2M ohms and try 
again, until you get a proper reading. Write down this reading in(or by) 
the right column of the checklist in the assembly manual, in case you 
need to come back later and debug any further.

4) For some of the system you may see a slow change over time, but this 
should not be orders of magnitude and should NOT approach the limit 
listed in the checklist, so I suspect your reading on P2 P1 is ok in 
this case.

73'
Brian OZ2BRN
K2 # 6936

Den 05-12-2010 20:18, Paul Agoglia skrev:
> I have just finished the assembly of the K2 Control Board and am doing resistance checks, as per assembly instructions.  Since I have not done something like this before I am hoping I have interpreted the directions correctly.  The directions say to take measurements with respect to ground.  I am taking that to mean that after I set my multimeter to an appropriate ohms range, that I touch one test lead to the pin to be tested, and the other test lead to a place on the circuit board that is labeled 'ground'.
> Can someone tell me if my interpretation of the directions is correct, and if so, then I have the following readings.  I have highlighted in red the readings that do not fall within the expected outcomes.
> Any insights would be helpful!
>
> I am using a Radio Shack DMM.
>
>
> Pin Tested                Should Read                What I got
>
> P2   P1>10k                         slowly moves to 360k -400k                                 U5  5V pin>2k                                13.96k
> U4  8V pin                3-7k                                3.58k
> Q1 Collector>1MOhm                      no reading
> Q2 Collector>1MOhm                      no reading
> U3 Pin 8>10k                            193k
> U6 Pin 13>100k                            316k
> U6 Pin 14>100k                            326k
> U6 Pin 29                70-90k                            13.97k
> U6 Pin 30                70-90k                            0.0 ohms
> U8 Pin2>100k                            257k
> U8 Pin 15>100k                            245k
> U8 Pin 16>100k                            251k
>
>
> Thanks,
>
> 73 de WN2K
>
> Paul Agoglia
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