[Heathkit] Puzzlement on HP-1144 A Power Supply

[TominNTX]

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
>