K2 build - Control board Resistor SIPs not marked right.

[Darwin, Keith]

I started melting solder this weekend.  Got to the part about installing
6 (or 7?) resistor SIPs on the control board.  Only 1 or 2 of them were
marked as indicated in the instructions.  The rest were substantially
different.  I checked each by measuring resistance between pin 1 and pin
2, and by counting leads.  Everything checked out so I installed them.
 
Did I do OK?
 
Also, I've been installing one component at a time and soldering it in.
The assembly instructions call for installing many and then soldering
them later.  I assume this is because you're likely to find you have a
wrong component in when you get to further down the list and discover
you can't find the one you need and have one that isn't called for.
With that assumption I've been carefully verifying the markings on the
component and on the board before I install & solder.
 
Am I doing OK?
 
I'm trying very hard to avoid any rework.  Rework means I have to take
the board to work and I don't want to do that.  I believe by being
careful I should be able to avoid any rework during the process.  We'll
see...
 
- Keith KD1E -
- K1  12xx -
- K2  5411-
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[Ian Stirling, G4ICV, AB2GR]

On Monday 20 March 2006 15:01, Darwin, Keith wrote:

> I'm trying very hard to avoid any rework.  Rework means I have to take
> the board to work and I don't want to do that.  I believe by being
> careful I should be able to avoid any rework during the process.  We'll
> see...

Keith,

  I built my K2 in June last year.
The most important step in my opinion is to
do a full inventory, at the same time partitioning
components that look similar to separate marked
locations.  I used two cheap drawer sets with around
a hundred drawers.  I marked the drawer number in the
inventory pages of the manual for every item.
  There are many reasons for doing this.

 Identifying parts is easier, e.g., there may be three
capacitors of the same value, and two that are similar
looking but different.  Identifying them and separating
them is easy at this stage when some items can be
identified by a process of elimination.

  An obvious advantage is that missing parts will be
discovered and a quick delivery from Elecraft won't
hold up progress.  My K2 kit did not have the fiber
washers used in mounting the output transistors or
speaker.

  Having completed a full inventory in this way,
every part has already been identified once and placed
so that it can be retrieved with a low chance of
fetching the wrong part.
  On fetching it to solder it in, I checked it a
second time.  And I made a third check with the
soldering iron in my hand.

  I had one missing hearbeat when the construction
notes referred to parts already installed, and
I had not installed them.  I had this awful fealing
of having installed the display or a large IC that
would need to be removed to install something I had
missed.  Luckily it was not critical.
  My error was that two pages had stuck together and
I had skipped two pages.  If I build another K2, I will
make sure that turning pages results in the correct
sequential page number.

  I'm sure triple checking every component was a
key to my not needing to rework anything.

Ian, G4ICV, AB2GR, K2 #4962
--
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[k6dgw]

Ian Stirling wrote:

> The most important step in my opinion is to
> do a full inventory, at the same time partitioning
> components that look similar to separate marked
> locations.  

I strongly second Ian's inventory comment, and his reasons for doing it.
   It's a bit of a drag, and we all want to heat up the solder station
and start the "real" building, but a complete inventory will likely
prevent micro, mini, and mega disasters.

Also, beware of inadvertently mixing up a part value with a reference
designator, there are a lot of words in the assembly instruction book,
and nearly all of them are important!  (e.g., and speaking from
experience, starting to install "C25" and fetching a 25pf cap for it
when the real value is 15pf)

Fred K6DGW
Auburn CA CM98lw
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[Alexandra Carter]

Yes, inventorying is a very good idea, and sometimes there are parts of
the same value but of two different types, like a regular 25pF cap and
an NPO one that's the same value, to be used in different areas.

The resistors are taken care of with the K2, no problems there, but
there are a lot of other parts. I found good old antistatic foam to be
great for sticking the parts in, I had all my caps by value smallest to
largest, etc., they the parts stick up in it so they're easy to pick
up.

73 de Alex NS6Y

On Mar 20, 2006, at 2:13 PM, Fred Jensen wrote:

> Ian Stirling wrote:
>
>> The most important step in my opinion is to
>> do a full inventory, at the same time partitioning
>> components that look similar to separate marked
>> locations.
>
> I strongly second Ian's inventory comment, and his reasons for doing
> it.   It's a bit of a drag, and we all want to heat up the solder
> station and start the "real" building, but a complete inventory will
> likely prevent micro, mini, and mega disasters.
>
> Also, beware of inadvertently mixing up a part value with a reference
> designator, there are a lot of words in the assembly instruction book,
> and nearly all of them are important!  (e.g., and speaking from
> experience, starting to install "C25" and fetching a 25pf cap for it
> when the real value is 15pf)
>
> Fred K6DGW
> Auburn CA CM98lw
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>

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[Ron D'Eau Claire-2]

Keith KD1E asked:

I've been installing one component at a time and soldering it in. The
assembly instructions call for installing many and then soldering them
later.  I assume this is because you're likely to find you have a wrong
component in when you get to further down the list and discover you can't
find the one you need and have one that isn't called for. With that
assumption I've been carefully verifying the markings on the component and
on the board before I install & solder.
 
Am I doing OK?

----------------------------

You'll find many of the later Elecraft manuals call for installing and
soldering one part at a time. Either way is okay. I prefer the one part at a
time method for a couple of reasons. One is that I hate dealing with a nest
of leads all sticking out on the other side of the board. Second is that
it's very easy while  soldering to move a lead slightly so the part on the
other side is no longer sitting against the board, and it's not noticed
until it's been soldered.

Of course you can reheat while pressing down on the part, but that's just
extra work as far as I'm concerned.

Like you, I hate to rework and go to great lengths to avoid it. So I use
this approach:

1) Read the step.

2) Find the part and confirm its value by looking at it or measuring it if
I'm not sure.

3) Find the location on the board and confirm that's the correct location by
looking back at the step (It's amazing how often C9 becomes C19 in my head!)


4) Place the part on the board.

5) Check the step and confirm both the position and value  of the part (It's
always a good idea to orient parts  so they can be read after installation
to aid troubleshooting at some future date, if necessary, unless the part
only goes one way due to polarity, etc.)

6) Solder the part in place and clip the leads as instructed.

7) Check off the step in the manual.

That process becomes automatic and I've only had to remove/reposition one
part to date. And that one was because I was too busy thinking about
photographing the step for the manual. When I was sitting at the computer
editing the photo to illustrate the step I was reading the numbers of the
part (multi-pin RP5 in the KX1 of all things) and looking at the procedure
and suddenly I realized the numbers didn't match. A quick check confirmed
that I had worded the step correctly but put the wrong on the board and then
photographed it for Figure 4!

Aaaargh!!! (And yes, I did take it off, but it's not something I'd recommend
doing on purpose...).

Ron AC7AC

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