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FUSE BLOWN AND NOW WHAT?

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Manuel Wilches

FUSE BLOWN AND NOW WHAT?

Hello everyone:
this time I have to come forward and confess with full exposure in broad day
light. I made a terrible mistake!

My KPA100 tested beautifully untill I got to the 20A power supply test (page
45). As I turned on the K2 (#8 step) nothing happened. I checked and I had
blown a fuse (the one that comes with the kit). I switched off everything
and went back to figure 32 (page 38)...I had reversed the wires on j4 when I
soldered them on the KPA100 board.

As I was taking my time to unsolder the cables, clean the pads etc. I
thought I could turn on the K2 on its own (as before) with my low power
supply and nothing else attached to it. Well here comes the suprise...I
cannot turn on the K2 at all. I have the 13,0 volts allright, coming out of
my small PS but nothing happens. What did I blow away?

J4 was plugged in P3, of course, when I blew the fuse.

Your comments and recommendations will be very much appreciated.

Thank you
73
Manuel Wilches
LU5OM
CT4IK

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Don Wilhelm-3

RE: FUSE BLOWN AND NOW WHAT?

Manuel,

It is only a guess, but I would expect that the auto-resetting fuse in the
K2 is open, and possibly Doide D12 is shorted, or both.

With the K2 power switch in the ON position, check the resistance to ground
from the cathode of D10, you should measure more than 500 ohms - if it is
less than 500, turn the power switch to OFF and check again, this time the
resistance should be infinite. If you have a low resistance with the power
switch in the OFF position, look for a short to ground (or a shorted D12).

If you do find a high resistance with the switch off, then connect your
power supply and measre voltages - first at the anode of D10, then the
cathode - next check at the center contacts of the power switch. If you
have voltage at the cathode of D10 and none at the power switch, F1 is
likely open.

Good luck and let us know what you find.

73,
Don W3FPR

> -----Original Message-----
>
> Hello everyone:
> this time I have to come forward and confess with full exposure
> in broad day
> light. I made a terrible mistake!
>
> My KPA100 tested beautifully untill I got to the 20A power supply
> test (page
> 45). As I turned on the K2 (#8 step) nothing happened. I checked
> and I had
> blown a fuse (the one that comes with the kit). I switched off everything
> and went back to figure 32 (page 38)...I had reversed the wires
> on j4 when I
> soldered them on the KPA100 board.
>
> As I was taking my time to unsolder the cables, clean the pads etc. I
> thought I could turn on the K2 on its own (as before) with my low power
> supply and nothing else attached to it. Well here comes the suprise...I
> cannot turn on the K2 at all. I have the 13,0 volts allright,
> coming out of
> my small PS but nothing happens. What did I blow away?
>
> J4 was plugged in P3, of course, when I blew the fuse.
>
> Your comments and recommendations will be very much appreciated.
>
> Thank you
> 73
> Manuel Wilches
> LU5OM
> CT4IK
>
>

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Manuel Wilches

Re: FUSE BLOWN AND NOW WHAT?

In reply to this post by Manuel Wilches

Good morning Don:
I forgot to tell you I have a RIGRUNNER 4012 with my small power supply for
the K2. Well, it had blown a fuse and I did not realise it. When I checked
everything this morning, after your email, the K2 is ON with no problems.
Thank you for the fuses!
Many many thanks Don
73
Manuel
LU5OM
CT4IK

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Manuel Wilches" <[hidden email]>
Sent: Saturday, April 01, 2006 2:15 AM
Subject: RE: [Elecraft] FUSE BLOWN AND NOW WHAT?

> Manuel,
>
> Given those readings, your diodes are OK.
>
> Check your Power Supply and its cable to the K2. With the K2 powered ON,
> what is the voltage at your power supply terminals? What is the voltage
> at
> the anode of D10? If the two are substantially different, then you should
> re-check your power cable for good solder connections at both ends.
>
> 73,
> Don W3FPR
>
>> -----Original Message-----
>> From: Manuel Wilches [mailto:[hidden email]]
>> Sent: Friday, March 31, 2006 11:48 PM
>> To: [hidden email]
>> Subject: Re: [Elecraft] FUSE BLOWN AND NOW WHAT?
>>
>>
>> Don:
>> Thank you very much
>> R seems to be higher than 500 ohms. I am not really sure...I get
>> all kinds
>> of readings...voltage readings seem to be more reliable with my DMM.
>> When I switch ON it is infinite (1)..I get a "1" in all ranges
>> I checked F1 and I get continuity when I switch it on
>> I checked voltages as follows:
>> Cathode of D10= 2.40
>> Anode of D10= 2.40
>> Cathode of D12= 2.31
>> Anothe of D12=0
>> However, the power supply is delivering 12.50 v but, when I switch ON my
>> reading is only 2.31/2.40 v at the input of the rig. This doesn't sound
>> right to me...it should be 12.5 v right?
>>
>> Is there a reliable way to test the diodes without desoldering them?
>> Thank you
>> 73
>> Manuel
>> LU5ON
>>
>> ----- Original Message -----
>> From: "Don Wilhelm" <[hidden email]>
>> To: "Manuel Wilches" <[hidden email]>;
>> <[hidden email]>
>> Sent: Friday, March 31, 2006 10:57 PM
>> Subject: RE: [Elecraft] FUSE BLOWN AND NOW WHAT?
>>
>>
>> > Manuel,
>> >
>> > It is only a guess, but I would expect that the auto-resetting
>> fuse in the
>> > K2 is open, and possibly Doide D12 is shorted, or both.
>> >
>> > With the K2 power switch in the ON position, check the resistance to
>> > ground
>> > from the cathode of D10, you should measure more than 500 ohms
>> - if it is
>> > less than 500, turn the power switch to OFF and check again,
>> this time the
>> > resistance should be infinite. If you have a low resistance with the
>> > power
>> > switch in the OFF position, look for a short to ground (or a
>> shorted D12).
>> >
>> > If you do find a high resistance with the switch off, then connect your
>> > power supply and measre voltages - first at the anode of D10, then the
>> > cathode - next check at the center contacts of the power switch. If
>> > you
>> > have voltage at the cathode of D10 and none at the power switch, F1 is
>> > likely open.
>> >
>> > Good luck and let us know what you find.
>> >
>> > 73,
>> > Don W3FPR
>> >
>> >> -----Original Message-----
>> >>
>> >> Hello everyone:
>> >> this time I have to come forward and confess with full exposure
>> >> in broad day
>> >> light. I made a terrible mistake!
>> >>
>> >> My KPA100 tested beautifully untill I got to the 20A power supply
>> >> test (page
>> >> 45). As I turned on the K2 (#8 step) nothing happened. I checked
>> >> and I had
>> >> blown a fuse (the one that comes with the kit). I switched off
>> everything
>> >> and went back to figure 32 (page 38)...I had reversed the wires
>> >> on j4 when I
>> >> soldered them on the KPA100 board.
>> >>
>> >> As I was taking my time to unsolder the cables, clean the pads etc. I
>> >> thought I could turn on the K2 on its own (as before) with my
>> low power
>> >> supply and nothing else attached to it. Well here comes the
>> >> suprise...I
>> >> cannot turn on the K2 at all. I have the 13,0 volts allright,
>> >> coming out of
>> >> my small PS but nothing happens. What did I blow away?
>> >>
>> >> J4 was plugged in P3, of course, when I blew the fuse.
>> >>
>> >> Your comments and recommendations will be very much appreciated.
>> >>
>> >> Thank you
>> >> 73
>> >> Manuel Wilches
>> >> LU5OM
>> >> CT4IK
>> >>
>> >>
>> >
>>
>>
>>
>> --
>> No virus found in this incoming message.
>> Checked by AVG Free Edition.
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>>
>>
>