Elektor Formant Modular

<wizard of oz mode on>

You don't need a MODULE... what you need is a dummy LOAD.

(no offense) Do you know how to use Ohms Law ???

I ask because you can calculate a number of resistive loads, and
wattages...
that you can use to safely test a power supply without blowing up
modules.
If not, contact me off/on list and I'll help you.

First of all, with the positive probe of your VOM on "0 volts" and the
negative probe on the -15V you should read "15 volts"   I'm assuming
that
you have the old meter with a pointer. Most modern ones do not care
which
lead is where, they will still read OK.

It seems like you are still missing a -15V supply.  If so fix THAT
first...

You might have two problems, a broken power supply AND a broken module.
But if the PS is not working, you will never get the module going
either.

Let me know about the load resistors.  You want to calculate some value
that
will draw some current from the supply, but not a huge amount. You need
to check
the wattage of the resistors as well.  Wirewound or Carbon Comp
resistors are very forgiving of short overloads... film resistors are
less so.

over:

H^) harry

markfrancombe wrote:

>  OK I have tidied up my Old Formant PSU, Hurrah.. looks nice, stuck my
>
> (misunderstood) voltmeter on the wires and I get +15 where it should
> be +5 where THAT should be.. 0 on well um.. zero.. but.. how do I
> know it the -15 is working? (tried reversing the red and black
> probes.. no effect).. Anyway seems to be working... so
>
> I connect up an ADSR. Now thos of you that remember, I blew one, I
> think, connecting to my Blacet PSU... Now I know I blew it.. dead..
> so I chnge the IC's (yes I had cleverly bought a bunch of spares..)
> now when I connect (and please bare in mind that THIS ADSR used to
> work on THIS PSU) I feel the IC's and sure enough.. one is heating
> up ... I pull the plug.
>
> What do I know? My ADSR is blowing (maybe on ALL PSU's) particularly
> on one IC? Maybe the old ones are OK? (apart from this one)
>
> Questions?
>
> Well, How can I find out why this is happening.. believe me Ive
> stared at the circuit long enough looking for breaks and blobs etc...
>
> maybe its time to try a different module? a VCO perhaps?
>
> Next time I plug it in Im going to use a resistor to cushion the
> voltage
>
> Kris, you said you may have some way of telling if modules worked?
> you said...
> I think I have some test sequences in my report if you want
> I'll send you it ..
> er.. yes please!!
>
>
>
>
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