Hello and welcome to the Polykit channel. Today's
video is a bit different. I'm looking into fixing an old Italian synthesizer drum module. It
is called Elka OMB3. I read somewhere OMB stands for one man band. I don't know if
that's true. I think it's from 1988 and in a pretty good shape – at least on the outside.
The module has two instrument and a bass section which can be controlled by MIDI. There are several
different instruments that can be selected. Instruments can be controlled on separate
MIDI channels or on a split keyboard. It also has predefined rhythms and arrangements which
accompany the player. The rhythm's got additional intro, ending and fill-in patterns. Volumes
of every section can be adjusted separately. As far as I know the module
is not even powering on. So first we take a look on the inside and
see what is going on. Okay let's open it up. There were no real obvious
problems on a first look. I checked the fuses and measured voltages
on the power supply board.
All seems fine. One of the voltage regulators obviously has been
replaced. So I looked it up in the datasheet. The datasheet states a 5 volt regulator but
it has been replaced by a 6 volt regulator. Hard to tell why someone did this. Maybe
there was no correct regulator at hand. So I'm going to revert this. I'm also going
to replace all the electrolytic capacitors. They're over 30 years old and this is
something that is going to fail eventually. In the service manual there is a notice
that it is advised to replace two resistors on the output stage to increase the
output level. This hasn't been done so I replaced both resistors as well.
It should triple the output volume. On the CPU board I replaced
the empty memory battery so it should be possible to store settings
again. I also replaced all capacitors here. After this I dared to connect it to mains
power but still nothing on the front panel. While measuring voltages on the regulator
I noticed that it dropped to one volt. This means that there is a short circuit
somewhere on the front panel board because beforehand I only measured without
it being connected to the CPU board.
And indeed while measuring between plus
5 volts and ground on the front panel it confirmed that there is a
short circuit on the board. So I took everything apart and also
replaced the capacitors on this board. It came out that one of the capacitors had a
resistance of 0 ohms and caused the short circuit. After giving everything a good clean and
putting it back together I tested it again and voila the module is powering on. So I hooked
it up to a MIDI keyboard. Let's give it a try. Okay, pretty cheesy! But I guess
this counts as a one-man band. The repair was a great success. Now the
instrument is in a pretty good condition. Also if you are interested in content like
this please subscribe to the channel and hit the like button. This helps a lot to keep
me motivated in doing videos like this. Alright, that's all for today.
Thanks for watching and bye for now.