A fluke may have fried my KX3 and KXPA100 I need advice
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I power my KXPA100 with an old reliable Astron RS35A power supply that I
have used for years. I have it up on a 3/8 in spacer above the carpet to keep it a bit cooler. I power my KX3 from the back of the KXPA100. I had the amp and KX3 on when a loose usb cable that was normally connected between my computer and my Signalink, had been disconnected to connect the signalink to my Raspberry Pi. While the USB cable connected to the computer was loose, it curled around I accidently kicked it and it slid under the power supply and contacted one of nuts on the bottom of the power supply and sparked. My KX3 stayed on for a few seconds, then shut off. When I tried to power it up again, it stayed on for about a second or so, then powered off. I checked the Astron power supply and it continues to put out 14.5V. I connected it back to one of the two Anderson PP connectors on the KXPA100 and there are no led's lighting up when the KXPA100 is on. I put a volt meter to the other Anderson Power Pole at the back of the KXPA100 and it is showing 4.6 v. output, not the normal 12 + V. I connected the 14.5 v. supply directly to the KX3 and it behaves the same; stays on for a second or so, then powers off. So, it appears that usb cable that found it's way under my power supply, has done some kind of damage to both my KXPA100 and KX3. I know there is no service currently at Elecraft, and when service resumes, it may be months before I can get the equipment repaired. To say I am frustrated would be a gross understatement. I can use my K2 and KX2, but both will be QRP. I am turning to the group to get any advice you might have at this point. Thanks so much! 73, Terry, N7TB ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
A fluke may have fried my KX3 and KXPA100 I need advice
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"While the USB cable connected to the computer was loose, it curled around I accidently kicked it and it slid under the power supply and contacted one of nuts on the bottom of the power supply and sparked."
The most likely contact scenario would seem to be that the shell of the USB connector made contact with a grounded nut on the power supply. What is the voltage of the PSU chassis relative to the PC chassis (or USB shell if using a laptop with no exposed chassis)? Andy, k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: A fluke may have fried my KX3 and KXPA100 I need advice
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"The most likely contact scenario would seem to be that the shell of the USB connector made contact with a grounded nut on the power supply. "
I received an email that said Astron power supplies have exposed transistors that are not at ground potential. That prompted me to investigate the Astron design. Page 13 of this paper http://www.wb1gof.org/files/AstronPDF.pdf shows the bottom of the case has an exposed stud/nut with 13.8 VDC. It may be interesting to find out (by analysis) what the PSU does if this stud is grounded. If the output voltage goes high it could explain the KXPA100 and KX3 failures. Maybe someone already knows the answer. Andy, k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Those exposed nuts are supposed to have plastic covers over them...
Chuck Hawley [hidden email] Amateur Radio, KE9UW aka Jack, BMW Motorcycles ________________________________ From: [hidden email] <[hidden email]> on behalf of Andy Durbin <[hidden email]> Sent: Friday, May 22, 2020 8:24 AM To: [hidden email] <[hidden email]> Subject: Re: [Elecraft] A fluke may have fried my KX3 and KXPA100 I need advice "The most likely contact scenario would seem to be that the shell of the USB connector made contact with a grounded nut on the power supply. " I received an email that said Astron power supplies have exposed transistors that are not at ground potential. That prompted me to investigate the Astron design. Page 13 of this paper http://www.wb1gof.org/files/AstronPDF.pdf shows the bottom of the case has an exposed stud/nut with 13.8 VDC. It may be interesting to find out (by analysis) what the PSU does if this stud is grounded. If the output voltage goes high it could explain the KXPA100 and KX3 failures. Maybe someone already knows the answer. Andy, k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email]
Chuck, KE9UW
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Re: A fluke may have fried my KX3 and KXPA100 I need advice
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In reply to this post by Terry
Now that you know it is the Power Supply, a couple of things to check.
Unplug it and let it clear out the cob webs. There are some fault protection modes that only clear with removing power and letting things discharge. Specifically, the crowbar circuit may not "uncrowbar" until everything is discharged. Second, you may have to do surgery. I have replaced transistors and LM723 chips before. The resource that Andy, K3WYC, posted is invaluable for getting your power supply back to the land of the living. Good luck. Tim Raymer 73 de KA0OUV -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of [hidden email] Sent: Thursday, May 21, 2020 22:46 To: [hidden email] Subject: [Elecraft] A fluke may have fried my KX3 and KXPA100 I need advice I power my KXPA100 with an old reliable Astron RS35A power supply that I have used for years. I have it up on a 3/8 in spacer above the carpet to keep it a bit cooler. I power my KX3 from the back of the KXPA100. I had the amp and KX3 on when a loose usb cable that was normally connected between my computer and my Signalink, had been disconnected to connect the signalink to my Raspberry Pi. While the USB cable connected to the computer was loose, it curled around I accidently kicked it and it slid under the power supply and contacted one of nuts on the bottom of the power supply and sparked. My KX3 stayed on for a few seconds, then shut off. When I tried to power it up again, it stayed on for about a second or so, then powered off. I checked the Astron power supply and it continues to put out 14.5V. I connected it back to one of the two Anderson PP connectors on the KXPA100 and there are no led's lighting up when the KXPA100 is on. I put a volt meter to the other Anderson Power Pole at the back of the KXPA100 and it is showing 4.6 v. output, not the normal 12 + V. I connected the 14.5 v. supply directly to the KX3 and it behaves the same; stays on for a second or so, then powers off. So, it appears that usb cable that found it's way under my power supply, has done some kind of damage to both my KXPA100 and KX3. I know there is no service currently at Elecraft, and when service resumes, it may be months before I can get the equipment repaired. To say I am frustrated would be a gross understatement. I can use my K2 and KX2, but both will be QRP. I am turning to the group to get any advice you might have at this point. Thanks so much! 73, Terry, N7TB ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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