[Elecraft] KRC2 silkscreen gotcha

[Rich]

Well I have a negative voltage on U2 pin8 but it is 3 volts higher than 
the manual.   Probably not an issue

Rich

On 11/19/2020 16:58 PM, Paul Fletcher wrote:
> The circuit diagram and the parts placement in the manual are correct. 
> On mine it was the silkscreen for R12 and R13 that was reversed. Let 
> Jack do some digging as it’s possible (from his comments) that this 
> doesn’t affect all boards. Mine only arrived a few days ago. The easy 
> way to check if there is an issue is to check there is the correct 
> negative voltage on pin 8 of U2. Mine was almost 0V before swapping 
> the resistors.
>
>> On 19 Nov 2020, at 21:41, Rich <rwnewbould at comcast.net 
>> <mailto:rwnewbould at comcast.net>> wrote:
>>
>> Thanks for the info.   Could you post the correct value of R12 and R13?
>>
>> Mine was back at Elecraft way back.   I want to make sure it is 
>> already not corrected
>>
>> Based on your info R12 should be 47ohm, correct?
>>
>>
>> Thanks
>>
>> Rich
>>
>> On 11/19/2020 15:52 PM, Paul GACEK via Elecraft wrote:
>>> Hi Paul
>>>
>>> Thanks for the heads up.
>>>
>>> I had some communication issues with my KRC2 in that it worked like 
>>> a champ with my K2 but not so with my KX3.
>>>
>>> I’m going to crack open my krc2 shortly and see what values I have 
>>> in those two resistor locations.
>>>
>>> What radio where you using with the KRC2?
>>>
>>> Paul
>>> W6PNG/M0SNA
>>> www.nomadic.blog <http://www.nomadic.blog>
>>>
>>>> On Nov 19, 2020, at 12:47 PM, Wes <wes_n7ws at triconet.org> wrote:
>>>>
>>>> Thanks.  I've owned one of these for years and as I recall, it's 
>>>> always been a problem so it's been resigned to the junk box.
>>>>
>>>> Maybe I can resurrect it to make it useful for something.
>>>>
>>>> Wes  N7WS
>>>>
>>>>> On 11/19/2020 12:58 PM, Paul Fletcher via Elecraft 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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