Doepfer

Help! Um, I was just programming away on my a100 and all of a sudden 
without cause or warning I lost all power!!!! where's the fuse? 
Anyone know what the heck might have caused this? Someone help 
please!!!????

Ben

Hi Ben,

> Help! Um, I was just programming away on my a100 and all of a 
sudden 
> without cause or warning I lost all power!!!! where's the fuse? 
> Anyone know what the heck might have caused this? Someone help 
> please!!!????

Take the plug out of the back of the case. Immediately above the 
where the plug fits is where the fuse is, you'll need to lever it out 
with a screwdriver or the like, from underneath. The fuses are not 
ordinary 13-amp plug types, but special 'time-lag' ones. (It would be 
as well to check the one in the plug too, to see which has blown.) 
Maplin sell the time-lag ones, so I'm sorry to say you will probably 
not get it going again straight away - use the time to try and 
establish what happened(!). If it's not an obvious wayward piece of 
metal shorting something across one of the boards, then it's hard to 
suggest what it might be - generally all modules have short circuit 
protection built in, because the very act of inserting patch leads 
tends to short things momentarily to ground, so it's unlikely to be a 
loose or dangling lead. You could try taking your current patch apart 
lead-by-lead to see if you might have wired up something in a non-
nice way (though again this Doepfer stuff seems pretty unburstable 
from that point of view, so I think this is very unlikely). The only 
time it happened to me is when I was using it power something on a 
breadboard - I connected an op amp the wrong way - and it blew the 
fuse in short order (chip still seemed to work though!).

Tim

Ok, I replaced the fuse in the power plug and all is good again, but 
Doug at En-port (u.s. retailer and representative) told me to use a 
fast blow fuse. You say slow blow type. Anyone else have input or 
know where I can find the spec? I looked on the doepfer site but it 
didnt' really say when I looked at the power supply manual page.
I'm going to wait until I get responses to get back to programming.
Time to watch a movie! :)
and yea. first things I did were to unplug power and patch leads... 
just makes a guy panic when his favorite synth tells him NO! 

thanks alot. 
ben

--- In Doepfer_a100@yahoogroups.com, "Tim Stinchcombe <timothy@t...>" 
<timothy@t...> wrote:
 
> Take the plug out of the back of the case. Immediately above the 
> where the plug fits is where the fuse is, you'll need to lever it 
out 
> with a screwdriver or the like, from underneath. The fuses are not 
> ordinary 13-amp plug types, but special 'time-lag' ones. (It would 
be 
> as well to check the one in the plug too, to see which has blown.) 
> Maplin sell the time-lag ones, so I'm sorry to say you will 
probably 
> not get it going again straight away - use the time to try and 
> establish what happened(!). If it's not an obvious wayward piece of 
> metal shorting something across one of the boards, then it's hard 
to 
> suggest what it might be - generally all modules have short circuit 
> protection built in, because the very act of inserting patch leads 
> tends to short things momentarily to ground, so it's unlikely to be 
a 
> loose or dangling lead. You could try taking your current patch 
apart 
> lead-by-lead to see if you might have wired up something in a non-
> nice way (though again this Doepfer stuff seems pretty unburstable 
> from that point of view, so I think this is very unlikely). The 
only 

> time it happened to me is when I was using it power something on a 
> breadboard - I connected an op amp the wrong way - and it blew the 
> fuse in short order (chip still seemed to work though!).
> 
> Tim

Hi Ben,

> Ok, I replaced the fuse in the power plug and all is good again, 
but 
> Doug at En-port (u.s. retailer and representative) told me to use a 
> fast blow fuse. You say slow blow type. Anyone else have input or 
> know where I can find the spec? I looked on the doepfer site but it 
> didnt' really say when I looked at the power supply manual page.
> I'm going to wait until I get responses to get back to programming.
> Time to watch a movie! :)
> and yea. first things I did were to unplug power and patch leads... 
> just makes a guy panic when his favorite synth tells him NO! 

Ah ha, I didn't realise you were in the States! However, I'm amazed 
it was the fuse in the plug. Since you use a lower mains voltage over 
there I don't know what typical ratings of mains fuses you get. In 
the UK we generally get 13, 5 and 1 amp fuses (for 250V AC). The fuse 
in the 'power receptacle' on the back of G6 case as I mentioned is 
rated at 250V and 100mA, i.e. 0.1 amps, which on the face of it 
appears to be *substantially* lower than those that might be in the 
plug. It is this fuse which is a 'time-lag' fuse - at least that is 
what it says on the box of replacements I got when I blew one of 
mine, and they look *identical* to the one I blew, even down to what 
looks like the manufacturer's stamp on them. I too cannot find 
anything in either the manual or the website, although when mine 
blew, I feel certain I found something somewhere, because like you I 
was extremely cautious (until I discovered the reversed op amp...)

So, none of this really helps anyway because all the fuse values are 
likely to be diferent where you are, although you could prise out the 
one in your case to see what it is marked as (?).

Tim

The fuses are not 
ordinary 13-amp plug types, but special 'time-lag' ones

time lag = SLO BLO = slow blow fuses.  You can get these at any 
electronics store.  In the US most hardware srtores will sell them 
as well.

Normal fuses (here referred to as FAST BLO are safer.  They go 
quickly - so if something serious happens chances are the fuse 
will go beforew the spike or whatever it is that's serging through 
the systems doesn't do damage for those short moments before 
the slo blo blows.
My suggestion:  just get a few of the correct value in fast blow.  
This way, if something happens and they go, you've got them on 
hand and back up in minutes.

Hi 

> My suggestion:  just get a few of the correct value in fast blow.
> This way, if something happens and they go, you've got them on
> hand and back up in minutes.
The fuse is only(!) there to prevent Powersupply hazards. If the
powersupply itself produces wrong voltages you have no chance - as far as I
remember the Doepfer powersupply does not have any fuses on the low voltage
side.

The slow blowing fuse makes sense, since the main current is drawn while
switching on the A-100 when the capacitors in the powersupply are loaded.
This short hogher current should be survived and do not harm the
transformer. But continuous too high currents might damage the transformer.
Only these currents will blow the fuse.

just my 2c'

Florian