WTB: Heath part # 442-48

[Kenneth G Dupuis]

Hi Chuck. I had the same problem with my SB-104A years ago but with the
12 regulator chip which is right next to the 5 volt chip on the
schematic. The Heath chip was not available and there was no garden
variety replacement, or so I thought. Take a good look at the schematic,
the 442-48 chip and transistor Q1 are really equivalent to a modern three
terminal 5 volt regulator chip to provide the +5 volts source output.
Remove the original Heath chip and substitute the three terminal chip
using old chip pin 2 as the 12 volt input, old chip pin 1 as ground ( the
case of the three terminal chip) and old chip pin 4 as the +5 volt
output. It might pay to remove transistor Q1 and bypass diode D206 to
eliminate the voltage drop.  When I did a similar exchange for the +12
volt regulator my SB-104A worked fine. The 5 volt chip is readily
available from Radio Shack and about a million other places. Check the
schematic for yourself in case I goofed on the directions. 73's Ken

On Thu, 16 Mar 2000 19:49:18 EST Chuck W4MIL <CEMILTON at AOL.COM> writes:
> Looking for this IC in order to restore +5v regulated to my SB104.
> Would
> consider purchase of the "B" board from an SB104 also.  Would like
> to
> purchase other SB104a parts.
>
> Any help on this is appreciated.
>
> Tnx es vy 73 de W4MIL
>
> Chuck
> Palm Coast FL
>
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