Doepfer

>  
> Hello,
> i just checked the previous posts about fuses and it also happens a lot to me,
> i would just like to make a question, tomorrow morning i¹m flying to madrid
> for a concert, i was just making my last revision and my last fuse blew :(
> i can¹t buy it anywhere before going and i don¹t know if i¹ll find a place to
> buy one there, the only fuses i found at home where 1.6A, can i use it
> instead? Is it too dangerous to do it?
> thankx in advance
> best regards
> andre
>  
>  
> 
> Max,
> 
> you find my comments written inline.
> 
> Best wishes
> Dieter Doepfer
> 
>> > Hi all,
>> > I have an amazing problem with my A100 system : it seems to be very
>> > capricious and it sometimes (about 1/2 probability) blows the fuse on
>> > power up. The case is a brand new portable suitcase (version 2). I
>> > tried different types of fuses (200 315 slow or fast, 500 fast), the
>> > 315 and 200 sometimes work, sometimes blow, the 500mA i tried blew on
>> > the first attempt but it was not a slow fuse so i guess it's normal.
> 
> In any case a time lag/slow blow fuse is required as it has to "survive" the
> transient pulse during power on. A fast or medium fuse will blow with a very
> high probability. The transient pulse is caused by the type of transformer
> (ring core/toroid, higher transient current than for standard transformers)
> and as all capacitors of the system have to be charged (e.g. each module
> contains capacitors across the supply voltages). A 315mA fuse (time lag !)
> should be sufficient from the theory (e.g. the specs from the transformer
> manufacturer) for 230V.
> 
>> > I checked the electric circuit of my home and it's round 238-240 V.
> 
> Maybe the slightly higher voltage cause the problem though the difference is
> not too much. You could try a fuse that has a bit more mA (e.g. 400 or 500
> mA). With this value you are still on the safe side as the fuse will blow in
> case of a short circuit or defective primary circuit of the transformer (as
> this is the job of the fuse).
> 
>> > The thing that really amazes me (i don't know if that's the right
>> > word...) is that the system sometimes work, and sometimes the fuse
>> > blows. I removed all modules and re-installed them all, nothing seems
>> > to be wrong inside the case ...
> 
> This may be caused by the exact moment when the power switch is turned "on".
> If the AC voltage at it's maximum the transient pulse is different compared
> to the condition that appears if the switch is operated while the AC voltage
> is close to zero. But normally the difference is absorbed by the time lag of
> the fuse.
> 
>> > Is there a simple solution to this problem (special fuse, higher
>> > current value) ? What is this fuse protecting ? What happens if you
>> > replace this fuse by a conductor ? Are there some things not to do
>> > that i should know about modules patching on power up ?
> 
> I'd recommend to use a (time lag) fuse with 400 or 500mA. As mentioned above
> you are still on the safe side with this value.
> 
>> > Thanks for your help and sorry for bad english,
>> > Max.
> 
>  
>     




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