HELP 442 626

[TChesek@Epix.Net]

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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Products bought, sold or traded here is the responsibility of the
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