K3 overheating smell after an hour or so.

[peterc281]

I know this is like asking how long is a piece of string but like they say, if you don't ask  
I recently replaced the volume control in my rig and since then if the rig has been running for an hour or so I notice the smell of an over-heated component when I come into the room.
The front of the right hand side panel near U12 5V regulator seems warmer to the touch than I would expect but everything is working fine.
I have done a careful visual inspection and found nothing.
It is a 100W rig with ATU and SubRcvr fitted and the input current with 13.5V is 1.54A which seems a bit high.
So the question... anybody got any ideas where I should look?

Peter VK3IJ

[Jack Berry]

Replaced with Elecraft supplied component? Does the volume control the same as before or is the trim different? Louder, softer?
Was anything besides the pot changed out?
Could a resistor near the pot be failing?

On Sep 11, 2013, at 4:59 AM, peterc281 <[hidden email]> wrote:

> I know this is like asking how long is a piece of string but like they say,
> if you don't ask  
> I recently replaced the volume control in my rig and since then if the rig
> has been running for an hour or so I notice the smell of an over-heated
> component when I come into the room.
> The front of the right hand side panel near U12 5V regulator seems warmer to
> the touch than I would expect but everything is working fine.
> I have done a careful visual inspection and found nothing.
> It is a 100W rig with ATU and SubRcvr fitted and the input current with
> 13.5V is 1.54A which seems a bit high.
> So the question... anybody got any ideas where I should look?
>
> Peter VK3IJ
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-overheating-smell-after-an-hour-or-so-tp7578806.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[peterc281]

The pot was damaged in transit returning from VK9NT and was replaced with an Elecraft supplied part. As I said in the original post everything is working fine, that's whats strange, replacing the pot may be coincidental.
Temperatures last night ... ambient 20c, FP 35c, PA 33c. I put a blob of heatsink paste to the screw that holds U12 and put my multimeter temp probe in that and in measured 40c.
Has anybody measured the current draw, is my 1.54A excessive?

Peter VK3IJ

[Bill W4ZV]

peterc281 wrote

Has anybody measured the current draw, is my 1.54A excessive?

With KRX3 activated mine measures ~1.4A @ 14.5V so I'd say not.

73,  Bill  W4ZV

[peterc281]

Thanks for the reply Bill. I remeasured the current. KRX3 on 1.82A off 1.52A so if the extra current is consistent with the KRX3 on and off with your measurement then I've got an extra 400mA sneaking off somewhere?

73, Peter VK3IJ
 

[Bill W4ZV]

peterc281 wrote

Thanks for the reply Bill. I remeasured the current. KRX3 on 1.82A off 1.52A so if the extra current is consistent with the KRX3 on and off with your measurement then I've got an extra 400mA sneaking off somewhere?

I measured mine again and got the following using the internal meter...1.15A KRX3 off and 1.45A on.  My readings jump around quite a bit so that's an eyeball average.  Yes you may have something else going on somewhere in the rig.  Probably time to contact k3support at elecraft.com.

73,  Bill