Doepfer

This seems to be a recurring issue around here.

I just installed two modules into my G6 frame to completely fill it
and the fuse blew on power up. I double checked all of the module
connections and there were no errors there and the total current
required by the installed modules is under 600mA so I think it is just
one of those transient power on spikes that seems to happen. 

I'm running the 240V PSU2 which specifies a 250mA slow blow fuse and I
know Dieter has mentioned that 300mA or maybe even 400mA would be OK
to use however I'm having trouble locating slow blow fuses in such low
current ratings, the lowest I can find here is 500mA. I know that this
is twice the specified current rating but would these be considered OK
to use given that in the case of a short to ground they will still blow?

Cheers,
Adam-V.

Hi Adam

> current ratings, the lowest I can find here is 500mA. I know that this
> is twice the specified current rating but would these be considered OK
> to use given that in the case of a short to ground they will still blow?
The Fuse is used to prevent high currents if a shorting happens inside 
the Transformer. If this happens currents far above 0.5A will happen and 
the fuse will blow nevertheless.

And once again: these fuses do not shield the modules from problems on 
the secondary (DC) side of the powersupply.

Florian

> I'm running the 240V PSU2 which specifies a 250mA slow blow fuse and I
> know Dieter has mentioned that 300mA or maybe even 400mA would be OK
> to use however I'm having trouble locating slow blow fuses in such low
> current ratings, the lowest I can find here is 500mA. I know that this
> is twice the specified current rating but would these be considered OK
> to use given that in the case of a short to ground they will still blow?
>
> Cheers,
> Adam-V.

Even 500 mA will be OK as the fuse will blow in case of a short circuit in
the mains section (that's the main reason for the fuse). I think we will
increase the fuse value once more though we never had a blown fuse in the
company or during exhibitions, work shops or similar. But of course we
cannot ignore the repetitive reports about blown fuses. Maybe the mains in
Germany behaves a bit different compared to other companies (e.g. slightly
different voltages or transients - I don't know).

Best wishes
Dieter Doepfer

hello all,
i had a taste of of blown fuses myself!
from my experience it happened when playing with laptop guys, 
specifically when they plug they're tranformer to the same power strip, 
normally there's a a visible short circuit that my suitcases don't like 
at all!
it happened a couple times in live situations with crowded stages...
my 5 cents
best
_ag

On Mar 21, 2007, at 4:24 PM, <hardware@doepfer.de> wrote:

> > I'm running the 240V PSU2 which specifies a 250mA slow blow fuse and 
> I
>  > know Dieter has mentioned that 300mA or maybe even 400mA would be OK
>  > to use however I'm having trouble locating slow blow fuses in such 
> low
>  > current ratings, the lowest I can find here is 500mA. I know that 
> this
>  > is twice the specified current rating but would these be considered 
> OK
>  > to use given that in the case of a short to ground they will still 
> blow?
>  >
>  > Cheers,
>  > Adam-V.
>
>  Even 500 mA will be OK as the fuse will blow in case of a short 
> circuit in
>  the mains section (that's the main reason for the fuse). I think we 
> will
>  increase the fuse value once more though we never had a blown fuse in 
> the
>  company or during exhibitions, work shops or similar. But of course we
>  cannot ignore the repetitive reports about blown fuses. Maybe the 
> mains in
>  Germany behaves a bit different compared to other companies (e.g. 
> slightly
>  different voltages or transients - I don't know).
>
>  Best wishes
>  Dieter Doepfer
>
>

Thanks for all the input guys.

I think you might right about this problem being environmental Dieter.
We run 240V @50Hz here in Australia but this can fluctuate. Maybe I
just switched on at the wrong time.

I'll try a 500mA Fuse and see how I go.

Cheers,
Adam-V