A very bad thing has happened....

[jean-charles maillet]

>I disconnect everything and check my power supply output, it's +15v
>and +1v (should be + / - 15). Ug. This is my small, .8amp supply, I use it
>because it's the only thing that fits into my super compact roadcase
>modular. So I go and get my big 3amp, International Power supply and hook
>it up to just one of the ASM-1s - all by itself. It still doesn't work, but
>worse yet, now this power supply is screwed up too - in the exact same way!
>+15v and +1v. Realizing I should have done this first, I check the ASM-1
>for shorts.

>I did this by checking the resistance between the various power
>supply connectors at the edge of the board, and all of them were well over
>2K.
>
>I don't get it, if there's a 2K load there - what screwed up my power
>supply?

this is a faulty test, your DC tester doesn't test at 15volt with all your
circuits running the way you had it before, if there's a bipolar amplifier
in your circuit with a shorted complimentary class-AB gain stage you won't
find out this way.

>
>Anybody have any ideas? Anyone know if the power supply just needs to be
>reset somehow (I'm going to call them tomorrow morning, but I need the
>synth this weekend, so I've gotta decide ASAP if I should have a new supply
>fedexed).
>What are the chances that I just fried all the 70 or so bi-polar op-amps in
>the synth????

chances are not, because all the leaky module is doing is pulling current
away from all other modules.  Normaly, audio circuits don't get damaged
running at lower voltages, because total dissipated power is roughly
proportional to supply voltage.

>How can I figure out whether another power supply will be
>fried if I plug it into the module - if not by measuring the resistance
>across the power supply inputs?  Yes, I checked +v to G, -v to G, and +v to
>-v.....
>
>
>- Any help would be greatly appreciated....
>
>- CList

I'd say there's likely no choice but to disconnect all modules from power
source (both +Vcc and -Vee), fix power source and reconnect one at a time
with fuses and ammeter in bias circuits to monitor current (don't assume
currents will be same).  If you don't find a unit sinking abnormal levels
of current then sit down and have a drink.

Once you've found which board is shorting out then you have to find which
part is shorting out the board (fun! ... sometimes helps to work in the
dark and wait for culrpite to glow red)

When fixing your old power supply bear in mind that you most likely fried
your regulator (look here first to save time), also look at bias resistors
around regulator for discoloration.  Sounds like you need to up the current
rating of your power source, either change to a higher current rating
regulator (same voltage -15) or connect a pair of the same in parallel with
47-Ohm resistors between outputs to allow for slight voltage offsets
between regulators.  You only need one set of bias caps and resistors to do
this - probably the hardest part is fitting proper heat sink depending on
room.  This is cheaper and barely more challenging than buying new bias
circuit.

Or build your own from scratch, nowadays it's a trivial thing ... go get
yourself a bunch of industrial 7815 and 7915's, a bunch of caps and
resistors, you're rockin' ... hell, wire a whole bunch in parallel ... go
crazy with cheapness ... it werks ...   :)~~

jc