[Elecraft] KRC2 silkscreen gotcha

[Paul Fletcher]

I have a Rev C PCB and the silkscreen does not match the diagram in the Rev C manual. On the PCB R12 and R13 are marked the opposite way round to the manual. I can send pics if you want them.

> On 19 Nov 2020, at 21:33, Jack Brindle <jackbrindle at me.com> wrote:
> 
> After seeing this report I pulled the Rev C PCB (the only PCB we have shipped for this product) and took a good look at it, then looked at the docs and finally the Gerbers for the board.
> R12 and R13 on the KRC2 PCB are properly labelled. R12, closest to the switches, is a 4.7K ohm resistor (yellow-violet-red) used to pull the RS232 line to -12V.
> R13 is next to it, closest to the DE9 connectors is a 47 ohm resistor (yellow-violet-black) and provides +12V power for the JFET.
> The legends on the PCB and in Figure 10 of the KRC2 Rev C manual are correct.
> 
> Now, what caused you to think they were backwards? And, let’s make sure that you do have a Rev C board in your KRC2.
> 
> 73,
> Jack, W6FB
> 
>> On Nov 19, 2020, at 11:58 AM, Paul Fletcher via Elecraft <elecraft at mailman.qth.net> wrote:
>> 
>> FAO anyone who's had issues getting the serial comms working on a KRC2:
>> 
>> R12 and R13 are transposed on the silkscreen on the PCB. I fell foul of this
>> when I recently built my KRC2 and it wouldn't communicate. After quick probe
>> around it was evident there was no negative voltage to the RS232 driver, U2.
>> A little further probing revealed no 12V present at R13 but there was at
>> R12. It was then I realised the component layout in the manual is different
>> to that marked on the PCB. A quick swap of resistors and everything works as
>> it should.
>> 
>> I've re-read the errata and the manual and there is no reference to this
>> issue. Apologies if it's been flagged up on here already but I couldn't find
>> anyone pointing this out though there do seem to be a few people with serial
>> comms issues with the KRC2.
>> 
>> Hopefully this is of assistance to someone.
>> 
>> 73 Paul M1PAF
>> 
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>