[Elecraft] KX-1 dead :(

[Tod Glenn]

On Oct 3, 2006, at 1:35 PM, <n0so at charter.net> <n0so at charter.net> wrote:

> ---- Tod Glenn <n7wd at cordite.com> wrote:
>>
>> On Oct 1, 2006, at 10:34 AM, Ron D'Eau Claire wrote:
>>
>>> Tod, look for a short in the +12 circuit to ground. The swollen
>>> batteries
>>> suggests they were feeding lots of current into a dead short for a
>>> long
>>> time.
>> All checked out OK
>>
>> I just completed the voltage checks on page 27 of the assembly manual
>>
>> Here's a comparison of the results when working versus now
>>
>> U1 pin 1 was 4.94v now 19.5mV
>> U3 pin 6 was 6.05v now 2.47v
>> D2 Anode was 14.83v now 2.7v
>> D2 cathode was 13.75v now 2.5v
>>
>> Voltage measured at the supply is 12.3v (Astron AS-35)
>>
>
> Tod,
>
> Take a look at the power cable and the power connector, J1. If you  
> measure 12.3V at the supply, you should measure very close to that  
> at the anode end of D2 unless there is an open or high resistance  
> in the power cable or in connector J1 or the PC board traces from  
> J1 to D2-anode or a short circuit in that area that is "pulling"  
> the supply voltage down. Try disconnecting the power cable from the  
> supply and measuring the resistance from the "+" supply lead to D2- 
> anode to check the path for continuity. If it's not very close to 0  
> ohms, something is wrong.

There's no continuity between + and the D2 anode


> Do the same with the supply "-" lead to a ground (one of the  
> mounting standoffs should work). That path should also be very  
> close to 0 ohms. While your measuring, measure from the power cable  
> "+" to "-" to insure it's not shorted.
>
> If you do find an open or a short in the power path and it's not a  
> soldering defect, look again for a short circuit on the "V+" signal  
> line shown on the schematic. Check this by measuring the resistance  
> from L3 on the bottom of the board to one of the mounting  
> standoffs. (This would be the first step on page 55 of the assembly  
> manual). If it measures less than 500 ohms, there is a short circuit.

The resistance between L3 and ground is about 1 K.



----
Tod Glenn
N7WD
NAQCC #1283
SKCC #1444
FISTS #12134
ARCI #12420
n7wd at cordite.com