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Jen SX1000 Servicing
The Jen SX1000 is a simple and fun hybrid monosynth, with
a digital oscillator, an analogue signal chain, and a rather
tasty 24db/oct low-pass filter.
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Price |
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| Master Oscillator Replacement + MIDI Interface
The core of the SX1000's voice is a digital chip that scans the keyboard and
generates the basic audio waveform. It is rather liable to die and almost
impossible to replace.
This upgrade replaces the voice chip with a plugin module that
revitalises the SX1000, and adds a MIDI input, with MIDI control
of note, pitch bend and filter cutoff.
You can read the Installation Manual
to see what is involved and for more details on the features of the
MIDI Upgrade.
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£125 / €150
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| Satin Silver Knob Kit
The original knobs on the SX1000 had coloured caps. Over time the
glue holding these caps on dries out and the caps fall off. The result is
a sad-looking Jenny.
I have managed to track down the original supplier of these knobs. While
they no longer make the coloured caps they can supply satin silver-capped knobs,
which I think make a very agreeable alternative (see
photo).
This kit includes a full set of 24 satin silver-capped knobs.
A 2mm screwdriver will be required for fitting them.
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£20 / €30
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Shipping is in addition to the above prices. Please contact me with your address
for postage and packaging costs.
For more details please contact me.
Note
- These items are to help out fellow Jen owners. I am not a service centre
or qualified service tech. I am a professional electronics engineer.
- Payment can be made by cash, cheque with card, or through PayPal.
The SX1000 is a fairly reliable machine. However, as well as the M110 dying
there are a few other common faults that are quite easy to repair.
- Broken glide oscillator
- Symptoms: You play a key, and the note sounds. Then you play a different key
but it sounds the same pitch. This fault even occurs with the MIDI retrofit.
Cause: Both the M110 and the MIDI retrofit need the glide oscillator
to move from one note to the next. If the glide oscillator has stopped working
then the pitch will not change.
Fix #1: The glide pot needs cleaning. First try turning
the glide control full circle a few times (first left, then right, then left, etc)
to see if that helps. Otherwise open the synth and squirt some switch cleaner into the
pot. If that fails, replace the pot.
Fix #2: The glide oscillator is a simple circuit based around
a single op-amp. It is located on the small PCB at the lower-left of the front panel,
together with the noise generator (MM3857N).
The original was a LF351. A good replacement is the TL071 or TL081. Both are readily
available from online suppliers or your local electronics store (e.g., Maplin in the UK).
Just remove the old chip and fit the new one, making sure it is the same way round.
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