Re: [Elecraft] K2 RF Board resistance checks - not in spec

2010-05-24 Thread Steve KC8QVO

I also found pins 29 and 30 (dot/dash) on U6 on the Control Board to have
higher than spec resistance, 96.7k and 96.5k respectively. They should be
70-90k. 

Weird. 

Steve, KC8QVO 
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Re: [Elecraft] K2 RF Board resistance checks - not in spec

2010-05-23 Thread Don Wilhelm
Steve,

Those resistance readings are too low, and you will have to find the cause.
What I believe is happening is that the low resistance on the paddle 
connections is triggering the circuits to go into a transmit state - and 
if that happens, the buttons do not work nor will the encoder change 
frequency.

Do you have anything plugged into the key jack?  If so, remove it and 
remeasure.
Did you make the measurement after the RF Board and the Control Board 
had been connected?  If so, then those readings are intended to be done 
on the RF Board alone.
If still low, check for solder bridges - check RF Board J8 pins 17 and 
18 carefully.  If there is a large deposit of solder, wich away the excess.
As a last resort, lift one end of R1 and R2 and remeasure the resistance 
both at the key jack and at J8 pins 17 and 18 - both should be greater 
than 1 megohm.  If the key jack is low, you may have a defective key 
jack, but if J8 pins 17 and 18 are low, you have a short to another 
circuit somewhere.  Again, examine the soldering carefully.  Solder 
sufficient to only fill the thru-plated hole is all that is necessary.  
If you have a pile of solder much more than that, wick most all of it 
away, it is certain to cause trouble.

Please understand that I have no idea at this time about your soldering 
skills (no insult intended), but too much solder and not enough heat are 
common builder problems - the solder must flow out onto the solder pad 
and the lead, and excess solder will mask a bad connection.  Adjust the 
soldering station temperature so you can produce a good flow of molten 
solder in 2 to 3 seconds.

73,
Don W3FPR

Steve KC8QVO wrote:
> Here are my out-of-spec measurements. Any ideas?
> R1 = 96.4k
> R2 = 96.5k
>
> Both should be >1M. Everthing else in the list checks out (well above the
> lower spec limit). 
>
> At this point the rig powers up and gives me the 201 message, switches to
> ELECrAFt, then 7100.00c but the buttons and knobs don't work (the next step
> is to push the display button to see what the voltage reading is, switch
> back to VFO, and spin the VFO knob to observe the frequency change - neither
> the display button or the VFO knob do anything). 
>
> Steve, KC8QVO
>   
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[Elecraft] K2 RF Board resistance checks - not in spec

2010-05-23 Thread Steve KC8QVO

Here are my out-of-spec measurements. Any ideas?
R1 = 96.4k
R2 = 96.5k

Both should be >1M. Everthing else in the list checks out (well above the
lower spec limit). 

At this point the rig powers up and gives me the 201 message, switches to
ELECrAFt, then 7100.00c but the buttons and knobs don't work (the next step
is to push the display button to see what the voltage reading is, switch
back to VFO, and spin the VFO knob to observe the frequency change - neither
the display button or the VFO knob do anything). 

Steve, KC8QVO
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View this message in context: 
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