[Heathkit] Puzzlement on HP-1144 A Power Supply

[Donald Spoon]

Thanks!  I had found the first two references, but the last one was 
exactly what I was seeking!
This will be a great help now as well as complete the documentation for 
what I have.  Thanks Again!

Further info to the group:  It looks like it IS in the SB-104 after 
all!  After finishing a QSO on 40 Meters today and tuning up for a new 
freq for a Net later on, the SB-104 started making a loud arcing sound 
from the left rear area around the PS plug and Aux Plugs. No smoke and 
no flashes seen in daylight, but I bet I can find it after dark!  It was 
REALLY loud!  I was using the older PS too!  I guess the blowing fuses 
were trying to tell me something, and it just now made itself 
evident...  Now I have something to focus upon!

Cheers,
-Don Spoon-
K0APK

On 5/23/2011 3:30 PM, TominNTX wrote:
> Don,
>
> This looks like it might help:
>
> http://www.ki6yfq.com/manuals_schematics/Heathkit/other/HP-1144-MOD.pdf
>
> It's the Heath Mod Kit that adds the crowbar.
>
> You may have to go to the main web site first.
>
> I Googled heath hp 1144a to find several references.
>
> https://puck.nether.net/pipermail/boatanchors/1997-July/000443.html
>
> Here is a 1144A schematic URL
>
> http://www.hifi-manuals.com/Download/Heath-Company/HP-1144-A-schematic
>
> Good Luck,
>
> 73 Tom KC5INU
>
> Remember, the government cannot give anything to anyone that they have
> not first taken away from someone else.
> ------------------------------
>> Message: 6
>> Date: Mon, 23 May 2011 02:01:24 -0500
>> From: Donald Spoon<drspoon at sbcglobal.net>
>> Subject: [Heathkit] Puzzlement on HP-1144 A Power Supply
>> To: Heathkit<heathkit at mailman.qth.net>
>> Message-ID:<4DDA0644.8030601 at sbcglobal.net>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> I happen to have two Heathkit HP-1144 Power Supplies... just by a quirk
>> of fate.  The one that I had been using for the last 6-8 months started
>> blowing the 20 Amp fuse in the + 13.8 Volt supply line whenever I
>> pressed the "Tune" button on my SB-104.  It had done this once or twice
>> before, but a fuse replacement "fixed" it and I continued using it.
>> This time the condition seems permanent.
>>
>> On a whim, I tried the other (older) Power Supply, which worked fine,
>> and didn't blow fuses!  The SB-104 acts normal in every way with this
>> older PS.  Upon closer inspection, I discovered the one blowing the 20
>> Amp fuse was the HP-1144A model with the crowbar circuit, while the
>> other one that worked was the older HP-1144 without the crowbar.  As
>> luck would have it, the only documentation I have (including schematic)
>> is for the older one...  so I am at a loss as to where to start to
>> diagnose the problem.
>>
>> I have given the failing PS a good visual inspection and have reset the
>> voltage to 13.8 Volts as required.  I can vary the output voltage, and
>> the SB-104 will work without problems in the receive mode,  Once I push
>> the "Tune" button the fuse goes.  I think trigger for the crowbar is
>> overly sensitive.
>>
>> Where to start?  Has anyone run into this problem before and can give me
>> some pointers?  Does anyone have a readable schematic of the "A" circuit
>> that could be shared with me?
>>
>> All advise welcome!
>>
>> Cheers,
>> -Don Spoon-
>> K0APK
>>
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