On Sun, Nov 14, 2010 at 12:24 PM, Tony Duell <ard at p850ug1.demon.co.uk>wrote:
I have a critical ( late 80's microprocessor controlled ) piece of test
gear
no longer supported. The power supply is dead and
after sawing through
it's
exoskeleton I was meet with a large epoxy block
the size of the original
box. I don't intend to fix said power supply but rather to figure out
what
voltages it provided and use a modern switcher. I
know I need +12 and +5
as
there is a generic floppy drive and the logic /
processor uses +5. Any
ideas
how to strip the epoxy other than digging through
it with implements of
mass
destruction ? Any and all help is appreciated.
Itmight be easier to work out what the PSU needs to be than to dismantle
the origianl one.
Firstly, what is the instrument (People here have some amazing stuff, and
ity's possible somebody else has the same unit and can measure the output
voltages.
If not, then how many output wires are there? Presumably there are 3 for
the ground, +5V and +12V supplies. Is there a -12V (e.g. for an RS232
port) that you could identify?
What about the analogue side? This may well need a floating supply (that
is, one with a semarate ground rail, not the same as the logic supply
ground). Op=amps (if there are any) are likely to use something like a
+/-15V supply.
-tony
Tony,
It is a B & K Model 2102 Audio Analyzer. I'm certain it does have a negative
supply for the RS232 ( no Maxim chip back then ). P/S has two " Molex " type
connectors; one 9 pin male and one 12 pin female. It has a ridiculously
complex inter-connect so it will run at any " reasonable " input
voltage user selectable ( I don't care about the input voltage(s).
Definitely OP-Amps so I'm checking Voltage ratings on the bypass caps for a
clue on the analog plus and minus voltages. I hate digging thru epoxy. It's
like trying to recover peanuts from elephant poop. Thanks for the ideas
Tony.
Best regards, Steven