HP-1144 Question

[Benton's Mail]

Gary,
It sounds like one of your power supplies is an 1144A. If memory serves - 
and it's been along time-- the -1 circuit board was used in the original 
1144 units, and the -2 circuit board was used in the 1144A. The -2 circuit 
board contained a Crowbar circuit to provide overvoltage protection should a 
compnent in the 1144 fail. The hole for Q4 that you describe was for the 
stud mounted SCR. This -2 board and components were also offered as an 
upgrade kit for the princely sum of $9.00 back in the day.

The two brown wires go to the Gate (G goes to small hole) and Cathode ( wire 
from chasis ground to Large hole) on the SCR.
Heath's part number was 417-823 which was a NL576A. To the best of my 
knowledge, these are no longer available, but any 20-25 amp category stud 
mounted SCR should work fine.
Hope this helps.
Cheers!!
Benton  wb5twc


----- Original Message ----- 
From: "Gary H. Harmon, Jr" <gharmon at IDWORLD.NET>
To: <HEATH at LISTS.TEMPE.GOV>
Sent: Monday, March 23, 2009 1:53 PM
Subject: HP-1144 Question


>I have several HP-1144 AC power supplies and one of them has a different
> PCB.  It's marked 85-1928-2 while all the others are a dash one.  This 
> dash
> two has a hole for a Q4 (looks to be a stud mounted rectifier).  There are
> also two loose brown wires; one is from connection "G" and the other goes 
> to
> chassis ground.  Any ideas?  Anyone have a schematic of this particular
> power supply I can get?
>
> Thanks.
>
> Gary H. Harmon, Jr. / K5JWK
> 6003 Archwood
> San Antonio, TX 78239-1504
> 210.657.1549h
> 210.884.6926c
> gharmon at idworld.net
>
> "Retirement means everyday is a Saturday, except Sunday."
>
>
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