1 Feb
2011
1 Feb
'11
12:07 p.m.
Tony Duell wrote:
That seems a very common failing with various micro manufacturers - I wonder
why? Despite system design being done in-house, was PSU design typically
I ma pretty sure the C128 brick is a Commodore design.....
But yes, Astec PSUs turned up in all sorts of machines, and often
official schematics were unavialable. The TRS-80 Model 3 manuals (and I
aussem the Model 4 one too, it uses the same PSU) contains a schematic
which I assume has been obtained by somebody at Radio Shack
reverse-engineering the Astec PSU board - an making a right mess of it.
The scheamtics at drawn coudlnt do anythign useful!.
On the otehr hand, there;s the Sharp MZ700 manual. The user manual for
this home comptuer starts off telling you how to plug it into the mains
and into a TV set. Then there's the normal introduction to BASIC with
cartoons, etc. Than a section on amchine language programming. Then full
schematics of the machine and options -- including the SMPSU board. And
finally a commented lisitng of the monitor ROMs. Odd manual...
Odd, the
C128 and A500 bricks are easily opened an serviced. I seem to
Well, they did hide the case screws under little plastic caps, but that
is a minor problem...
There were no schematics for the PSUs in the appropriate service manuals
either, which was also a minor problem. outsourced to a different company? That might explain
the lack of PSU
schematics. Or did micro designers consider the logic servicable, and yet
Posibly safety-related. It's difficult to do serious harm to you or
somebody else with a 5V supply at th typical current available in a home
micro. It's ratehr easier to do serious harm with the mains. On ther
other hand, PSUs which start with a mains transfomer (whetehr the
regualtors are linear or switchers) are pretty safe to work on.
Hp did the opposite in some of their 'service manuals' They were
essentially boardswapper guides with no schematics of the logic at all,
but you did get full PSU schematics. Go figure.
-tony