Elecraft › [K2]

K2 Control Board Resistance Checks

Classic

List

Threaded

3 messages Options

pagoglia

K2 Control Board Resistance Checks

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
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

Re: K2 Control Board Resistance Checks

Paul,

Yes, you would connect one lead (usually the black one) of your DMM to
ground.

If by "no reading" you mean infinite resistance (the same thing the
meter displays when the leads are not touching anything), then those two
readings are correct.

The other "problem" I see is the measurements at U6 pins 29 and pin 30.
Are you certain you are counting the pins correctly. The pin numbering
on an IC proceeds around the chip in a counterclockwise manner (looking
from the top) - on U6, pin 21 is directly across the chip from pin 20.
If you counted the pins 21 -40 backwards, you would end up at pins 32
instead of 29 - which is the 5A voltage rail and your measurement looks
suspiciously like the reading you got at the 5 volt side of the 5 volt
regulator. Also you would have mistaken pin 31 for pin 30 and pin 31 is
ground which should properly give a 0.00 kohm reading.

73,
Don W3FPR

On 12/5/2010 2:18 PM, Paul Agoglia wrote:

> 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
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

OZ2BRN Brian Lodahl

Re: K2 Control Board Resistance Checks

In reply to this post by pagoglia

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: