KAT500 refuses to turn on

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KAT500 refuses to turn on

Elecraft mailing list
Hi All,I have the K line here. I was listening to a QSO and out of the blue my KAT500 lost power.I disconnected everything from the KAT500 and then reconnected. The power plug has 12 volts so that is not the problem.The KAT500 was set up to turn on automatically when I turned on the power supply and now that does not work anymore.When I press the mode button to turn on the tuner that does not work now either. Where do I start looking?Thanks, Jim Douglas  K2ZF
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Re: KAT500 refuses to turn on

Bob McGraw - K4TAX
I'd start by opening the box and check the input and output of the
regulator, U4, being a LM7805.   Should have ~12V on the input and 5V on
the output.  If there is not 12V on the input then check both sides of
the diode, D8, which is in series with the 12V input.  Also there is an
inductor/choke L9 in series with the 12 volt line to the LM7805.

If the LM7805 does not have 5V on the output, either it has failed or
there is a short which is pulling the 5V line to zero. Schematics are
available and the rest depends on your trouble shooting skills.

Otherwise, obtain an RA from Elecraft Tech Support.

73

Bob, K4TAX


On 2/14/2019 8:00 AM, Jim Douglas via Elecraft wrote:

> Hi All,I have the K line here. I was listening to a QSO and out of the blue my KAT500 lost power.I disconnected everything from the KAT500 and then reconnected. The power plug has 12 volts so that is not the problem.The KAT500 was set up to turn on automatically when I turned on the power supply and now that does not work anymore.When I press the mode button to turn on the tuner that does not work now either. Where do I start looking?Thanks, Jim Douglas  K2ZF
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Re: KAT500 refuses to turn on

wa2lbi@gmail.com
In reply to this post by Elecraft mailing list
Jim,

If you don't have a schematic you should download one.  According to the
schematic there isn't any internal fuse.
The 12VDC is passed from the rear panel jack through a polarity protection
diode to a choke then to a voltage regulator, a LM7805.

To start, you need to open the case and check that there is 12V on the jack
*inside* the case.  Then check if there is 5V at the regulator output.

If there isn't 5V at the outout check the regulator input side for
approximately 12VDC and work back through the choke and diode until you
find the defective component.

If the LM7805 has 5V on the output then it is likely there is a logic
failure and you should contact Elecraft.

Gl!

Ken
WA2LBI


On Thu, Feb 14, 2019, 09:01 Jim Douglas via Elecraft <
[hidden email] wrote:

> Hi All,I have the K line here. I was listening to a QSO and out of the
> blue my KAT500 lost power.I disconnected everything from the KAT500 and
> then reconnected. The power plug has 12 volts so that is not the
> problem.The KAT500 was set up to turn on automatically when I turned on the
> power supply and now that does not work anymore.When I press the mode
> button to turn on the tuner that does not work now either. Where do I start
> looking?


Thanks, Jim Douglas  K2ZF
> ____________________________________
>
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Re: KAT500 refuses to turn on

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On 2/14/2019 9:38 AM, Ken Winterling wrote:
> If you don't have a schematic you should download one.


I own a KAT500 but can't find the schematics on the Elecraft web site.
Where can I download them?

-Tony, K1KP

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Re: KAT500 refuses to turn on

Bob McGraw - K4TAX
I called Elecraft and ask if they would send the schematics for my
KAT500 and my KPA500.   In about 30 minutes they were in my e-mail in
box.  Very high quality printouts now reside in my manuals.

73

Bob, K4TAX



On 2/14/2019 11:03 AM, Tony Brock-Fisher via Elecraft wrote:

>
> On 2/14/2019 9:38 AM, Ken Winterling wrote:
>> If you don't have a schematic you should download one.
>
>
> I own a KAT500 but can't find the schematics on the Elecraft web site.
> Where can I download them?
>
> -Tony, K1KP
>
> ______________________________________________________________
> 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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