Fw: [HEATH-TEMPE] HELP 442 626

[TChesek@Epix.Net]

I neglected to mention in the last step which states "Connect other side of
that trimmer pot to circuit ground" that this connection is the Pin 4 hole
in the circuit board.

So when you are done Pin holes 1,2,4 have connections. Pin hole 3 no
connection. LM317T is a 3 pin regulator.

Tom

----- Original Message ----- 
From: "TChesek at Epix.Net" <tchesek at epix.net>
To: "Morry" <morry.ham at VERIZON.NET>; <HEATH at LISTSERV.TEMPE.GOV>
Sent: Thursday, May 18, 2006 8:32 PM
Subject: Re: [HEATH-TEMPE] HELP 442 626


> That chip is a 78MGT4C and obsolete. I recently repaired a HWA-2036-3 12
> volt power supply for a HW-2036A 2 meter FM Transceiver. I do not have the
> schematic for the HP 1175 PS but you can get the schematic for the
> HWA-2036-3 from http://www.tech-systems-labs.com/heath_schematic.htm and
> compare it to yours. That same chip was bad in my power supply also. I
went
> to Radio Shack and bought a LM317T  (RS part 276-1778) adjustable voltage
> regulator. I removed the 78MGT4C which is a 4 pin package and replaced it
> with the LM317T as follows:
>
> Pins 1 & 2 of the LM317T go to the same locations of where pins 1 & 2 were
> for the old regulator. Pin 3 of the LM317T is NOT connected to the circuit
> board and the Pin 3 hole in the circuit board stays empty. (I have the Pin
3
> leg of the regulator bent into the air)
>
> Place a 240 ohm (I used a 220) resistor across pins 2 & 3 of the LM317T.
>
> Connect one side of a 5K ohm (I used 10K) trimmer pot to pin 3 of LM317T
> also.
>
> Connect other side of that trimmer pot to circuit ground.
>
> That is all that I did and it works like a champ. Let us know how you make
> out.
>
> Tom K3TVC
>
>
>
>
>
> ----- Original Message ----- 
> From: "Morry" <morry.ham at VERIZON.NET>
> To: <HEATH at LISTSERV.TEMPE.GOV>
> Sent: Thursday, May 18, 2006 3:16 PM
> Subject: [HEATH-TEMPE] HELP 442 626
>
>
> > I'm trying to repair a Heath HP1175 PS  recently given to me. It is in
> > need of the 442-626 chip
> > I hve searched the archives etc and can't seem to find any help. I hate
> > to discard this supply.
> > Is their any help for me out their????????????????????
> > Mny tnx in advance es Best 73 Morry K3DPJ
> >
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