[sdiy] Elektron

Jean Bender lofideadbeat at gmail.com
Thu Jan 2 12:41:37 CET 2014

Well, i've measured again everything, but no way, i can't get any DC
current anywhere. I just can trace the AC voltage, which goes.. almost
every where !! It's really strange. I don't have +12v on C15, and no
VDC on C8 & C21...

I don't know how to check the schotky diodes. The current doesn't seem
to be rectified.. Maybe one of them is dead ? Or would the 10 000 uf
cap could cause such a problem if it was deffective ?

Thanks for the help !!


2013/12/31 Jean Bender <lofideadbeat at gmail.com>:
> !!!!! THANKS !!!!
> you gave me the informations i needed ! Well, now, just have to go
> back to my workshop and see what happens.. Thanks a lot, it will be
> really easier for me to try debbugging it !
> I understand what you mean about the analog ground. I thought about
> that when i took my measures and didn't understand anything.. So the
> pin out connector will help me !
> But for information, the unit is absolutely not powering up. No leds,
> nothing... And it's always been powered by the original elektron psu
> which is working !
> Cheers,
> Jean
> 2013/12/31 Mattias Rickardsson <mr at analogue.org>:
>> Sorry to hear about the sleeping Machinedrum...
>> How dead is it? Does it light up anything?
>> If it lights up but nothing starts, then it might be time to retire
>> the big capacitors in the PSU after a long and strenous life.
>> 6VAC is only to be expected at full current draw, so higher voltage is normal.
>> The digital section uses 4 schottky diodes to full-wave rectify the
>> AC. Then there is probably a 5 V regulator (LM2904T-5) and a 3.3V
>> regulator (LM317).
>> The analog section transforms the 6VAC up to 12VAC and half-wave
>> rectifies it and regulates to +/- 8V (with a 7808/7908). On the I/O
>> PCB there is an analog 5V regulation as well (LM317).
>> If you have disconnected the PSU PCB (which you should probably do
>> while measuring the PSU) then the regulated digital & analog voltages
>> are floating with respect to each other, i.e., you need to measure an
>> analog voltage in reference to an analog ground and vice versa.
>> Measuring between an analog voltage and digital ground could end up
>> anywhere.
>> There is a connector for 3.3V, another for 5V, and a 10-pin connector
>> with the following voltages:
>> -8VDC
>> 5VDC (MIDI)
>> +8VDC
>> Another thing to watch out for is if some component pins or some
>> heatsink has come in contact with the casing - this is not good and
>> can give similar problems.
>> Unless you find any clues so far, try measuring the voltage coming IN
>> to the LM317 (should be 6-8 VDC over for example C8, C21) and OUT from
>> the transformer (should be around 12 VDC over C15).
>> Good luck, and happy new drummachine year! :-)
>> /mr
>> On 30 December 2013 19:43, Jean Bender <lofideadbeat at gmail.com> wrote:
>>> Well, i've taken my measure with my multimeter. I switched from AC to
>>> DC as i know the lm** pinouts. I did that fastly this afternoon as i'm
>>> working this night and tomorrow. I'll go back to my workshop
>>> tomorrow..
>>> I should have taken some pictures or other regulators references..
>>> I'll send that tomorrow night or on Wednesday.
>>> The strange thing is even if powered, and with my AC current ok at the
>>> fuse output ( so just before the whole regulation unit), absolutely
>>> none of the regulator was heating. And they have pretty big power
>>> dissipation stuff !
>>> It's the first time i don't really understand a power supply, and as i
>>> don't have any schematics...
>>> Thanks for the help.
>>> 2013/12/30 Byron G. Jacquot <thescum at surfree.com>:
>>>>>Hi everybody !
>>>>>I've just bought an Elektron Machinedrum sps 1 ( first generation).
>>>>>The friend who sold it to me tested it before shipping, and it was
>>>>>Once i tried to plug it, it never started. I fisrt thought it wa sue
>>>>>to the external power supply ( it should give a 6v AC out), but no..
>>>>>except if 7,23v AC out is too bad..
>>>>>So i opened my sps1. The fuse is ok, the power connector also.. i can
>>>>>get my ac voltage at the fuse output.
>>>>>After that.. nothing. There are many regulators, but for most of them
>>>>>i can't figure how they work. I've just check a lm7808 and a lm317
>>>>>that don't deliver good voltages..
>>>>>And visually, no component seems to have burn..
>>>> There's likely nothing wrong with the AC supply.
>>>> External transformers are usually rated to deliver the stated Voltage at the stated current.  If you draw less current, the Voltage will be somewhat higher...7.23 seems about right for a 6VAC supply.
>>>> It's also pretty unusual that all of the voltage regulators would fail at once.  I'd suspect something that's common to all of them.  How are you measuring them?
>>>> If it was just shipped, perhaps a connector slipped out of place?
>>>> -Byron Jacquot
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>>> --
>>> Jean Bender
>>> Hak Lofi Record
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
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> --
> Jean Bender
> Hak Lofi Record

Jean Bender

Hak Lofi Record


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