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.

I checked the electric circuit of my home and it's round 238-240 V.

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 ...

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 ?

Thanks for your help and sorry for bad english,
Max.

One thing, I'm no expert, but NEVER replace a fuse by a conductor.
This could damage your system and possibly,and more importantly, yourself.

On 3/2/07, damaged_meat <francois.maxime@gmail.com> wrote:
>
>
>
>
>
>
> 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.
>
>  I checked the electric circuit of my home and it's round 238-240 V.
>
>  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 ...
>
>  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 ?
>
>  Thanks for your help and sorry for bad english,
>  Max.
>
>

--- In Doepfer_a100@yahoogroups.com, achtung_999
<heinrich.himmelwasser@...> wrote:
>
> One thing, I'm no expert, but NEVER replace a fuse by a conductor.
> This could damage your system and possibly,and more importantly,
yourself.

Yes, that could be dangerous =) i wouldn't have done it ! 
I'm just wondering what part of the system would be damaged if you
remove this fuse, would it be the PSU only or the PSU and the modules ?

I tried 400mA time lag fuses, the system always works when there's no
module plugged. When i start plugging modules (any type of module) the
fuse blows again when i power up back the system. I guess (and i hope)
any module is damaged because when the fuse doesn't blow on power up,
they all work well.
That really drives me mad, i can't figure out what's wrong. The system
have been working well 3 weeks and suddenly it decided to blow the fuses !

Is there any test i could do to locate the bug ?
If there is not think i'm going to bring it back to the shop, before i
do something wrong or dangerous.

Hi damaged_meat

> 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.
> 
> I checked the electric circuit of my home and it's round 238-240 V.
> 
> 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 ...
> 
> 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 ?
According to http://www.doepfer.de/a100z_e.htm the Powersupply II uses a 
transformer with 1200mA instead of the 650 mA of the old transformer. 
Also the the torroid transformers used in the new powersupply draw more 
current when switched on. So I assume that 400mA are definitely not 
enough for the fuse.

I think Dieter will jump in here on monday...

Florian

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.

>  
> 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.
> 
>  
>     




[Non-text portions of this message have been removed]

> > 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

For the time beeing the 1.6A may be used as it will blow in case of a short
circuit in the mains wiring. But you should replace the 1.6A fuse a.s.a.p.
by 400 or 500 mA (time lag!).

Best wishes
Dieter Doepfer