Where is the PSU fuse in a Doepfer case?

[felix le chat]

Hello,

I have the Doepfer 6u case and after about 1 year of use it stopped working (no module works).

Actually I was calibrating the ES-1, here is what I did:

1. power off
2. unscrew the ES-1 (left connected to the power bus
3. power on
4. nothing works anymore


So where can I find the PSU fuse?

Flc

[Reality Checkpoint]

I seem to remember that the fuse is in a tray above or below where the power cord enters the case. (At least that is with the power to the rear models).

Don't quote me though!

[felix le chat]

My case is nearly full of modules so I cannot see the PSU anymore; I do not understand if the fused is accessed by removing the rear PSU socket or by removing some modules

[levka]

The fuse is in the small space that is located above the 110/220 V power cord connector and below the on/off switch on the back of the case (outside)

You may need to pry a minuscule lid open with a small screwdriver.

[tIB]

^ this. Its just below where the kettle lead attaches. remove the lead and prise out the little fuse tray.

[felix le chat]

thanks a lot, I found it
so the fuse is blown and I need to replace it

but why did it blow? it never happened before actually


also, there is something I don't understand
why the psu is 1200mA and the required fuse "only" 400mA (the original fuse is a "L 250V T 400mA")?

Flc

[tIB]

they blow, I had one blow, got a new case, powered on and it blew...bought a load and expecting to have problems and been fine ever since for over a year. Probably worth checking connections of anything in case something has worked its way lose or something.

[felix le chat]

Also, I tried to check the total current draw of my modules, but only a few manufacturers give the current draw in the specifications.

Is there an Eurorack current draw database anywhere?

I have 21 modules, the case is 1200mA, really not sure if it's ok

Flc

[Reality Checkpoint]

Also, I tried to check the total current draw of my modules, but only a few manufacturers give the current draw in the specifications.

Is there an Eurorack current draw database anywhere?

I have 21 modules, the case is 1200mA, really not sure if it's ok

Flc

Doesn't the eurorack modular planner (see sticky at top of the page) have a power consumption figure for each module in it?

[daverj]

but why did it blow? it never happened before actually

here is what I did:

1. power off
2. unscrew the ES-1 (left connected to the power bus
3. power on
4. nothing works anymore

It sounds like you may have shorted the power supply connection in the ES-1 by letting it touch against a panel or some other piece of metal. If the +12 or -12 on that module shorted to ground, that would probably have blown the fuse.

also, there is something I don't understand
why the psu is 1200mA and the required fuse "only" 400mA (the original fuse is a "L 250V T 400mA")?

1200ma is the output rating (actually it's 1200ma of +12 and 1200ma of -12)

The fuse that blew is on the input, which is 110v or 220v AC. When the transformer converts the high AC voltage into a lower one, it also converts a low amount of current into a higher amount. So the current in to the power supply is lower than the current out.

[felix le chat]

Doesn't the eurorack modular planner (see sticky at top of the page) have a power consumption figure for each module in it?

Yes, but for most of the modules I have it quotes a current of 0 mA, which is not possible.

I really like this modular planner and I hope it will be updated in the future, because it could easily be the best Eurorack hub / database for accessing all information about any particular module (size, approx. price, depth, current, + links to user manual, manufacturer page, example videos and appropriated Muffwiggler/etc discussions).

Flc

[felix le chat]

It sounds like you may have shorted the power supply connection in the ES-1 by letting it touch against a panel or some other piece of metal. If the +12 or -12 on that module shorted to ground, that would probably have blown the fuse.

This should explain it indeed. I did this quite in a hurry and it's likely that some ES-1 connections touched the metal rail of the case.

1200ma is the output rating (actually it's 1200ma of +12 and 1200ma of -12)

The fuse that blew is on the input, which is 110v or 220v AC. When the transformer converts the high AC voltage into a lower one, it also converts a low amount of current into a higher amount. So the current in to the power supply is lower than the current out.

Yes, I was simply stupid or tired and forgot that the 1200mA current was quoted for a tension of 12V -- of course it's different in 220V

Flc

[felix le chat]

Problem fixed - a local electronics shop had the appropriated fuses and I bought 20 of them for 3 euros.
Everything works again correctly now

Thanks a lot everybody for your help

Flc

[levka]

...
also, there is something I don't understand
why the psu is 1200mA and the required fuse "only" 400mA (the original fuse is a "L 250V T 400mA")?

Flc

fuse is rated at 220V input voltage, output is rated at 12V

[jy]

Hello all,

I've had three fuses blow in the last month or so on one of my doepfer 6u cases (bought brand new 5 months ago) After the second fuse blew i tried to experiment with powering up procedures - i.e. everything else (controller, rack effects, etc) switched on first and lastly the cases (everything is powered via a surge-protected multi-socket extension) this has worked fine for a while - today i accidentally tried to power up with one of the cases on and it immediately blew again - surge box does not trip - anybody care to speculate on what i am doing wrong - i've got the correct rated fuses for UK voltage (slow blow) - should i just resign myself to making sure i always power up correctly or is this a symptom of something more seriously wrong with my case that could potentially damage my modules?

[daverj]

Have you added up the total amount of current that your modules are drawing? Is it close to the limit of the power supply?

I can think of two potential reasons for a fuse to blow:

1 - the total power draw is at or over the limit of the power supply

2 - Something that is plugged into one (or more) of the outputs of modules going to devices outside the modular case is causing excess power to be drawn at power up because the outside device is itself not yet powered up and it's circuitry is causing a short or heavy load on the output from the module. This in itself would not cause the fuse to blow, but if the modules add up to an amount of current close to the power supply limit, then this could push it past the limit.

[jy]

thanks for the advice daverj

although i don't think i'm anywhere near the total power limit - i'll spend some time doing my current draw sums tomorrow - and probably remove all the modules and systematically put them back in one by one and see at what point (if any) the problem reappears.
I'll report back sometime during the weekend.