[sdiy] Prophet 5 -15v rail is shorting... Need advice

[Gil W.]

NEWS:

I finally managed to locate a heating MC14016 chip,
took it out and got stable +14.80v for five minutes.

Then, suddenly to voltage dropped again !!

Am I doing any wrong ? I'm currently running the voice
board without the CEM and CA chips, to avoid ruining
them. Is that safe ?

I can't see why ICs will get defected so easily. I
first thought that the 14016 sponteneouly went bad,
but now I have the feeling that something knocks them
up !!




--- ASSI <Stromeko at compuserve.de> wrote:

> On Freitag 09 November 2007, Gil W. wrote:
> > What I got is even lower +15v voltages. This one
> has
> > dropped the voltage to below 14v !! So can we
> conclude
> > from this experiment that simply the P6
> transformer
> > cannot handle the Prophet's load ?
> 
> Again, if the specifications you gave are correct,
> that's implausible.  
> However if you want to be sure, you can put both
> transformers in 
> parallel (and in phase of course) at least as an
> experient and see if 
> this improves things.  If it does it still does not
> mean that the 
> transformer is inadequate, but at least it would
> point to a problem 
> before the regulators.
> 
> > Btw, the voltages going to the regulators with
> this
> > (the second) transformer, are:
> > +21.20v
> > -23v
> 
> >From the schematics this sounds about right
> (assuming that is an RMS 
> value) and the regulators should have no problem
> with the headroom - if 
> the filter capacitors in front of the regulators are
> correctly 
> dimensioned.  Can you check the ripple on the
> regulator inputs?
> 
> 
> Achim.
> -- 
> +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb
> Andromeda XTk]>+
> 
> Factory and User Sound Singles for Waldorf Q, microQ
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>
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> 
> 
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