APOB OSCar40 DIY
Projecttitel: APOB OSCar40 DIY
Status: DONE
Startdate: 11/2025
Duedate: 12/2025
Updated 02/2026
Manufacture link: Facebook group OSCAR40
IR HAM aka Apob is the developer , he offer assembled and DIY Versions.
Info:
this DIY project is a clone of the OSCAR Synth, its nearly a replica.
Its not for beginner, and my page isn't for reference or a true support.
there´s a disclaimer at the footage of this site.
Build Docs:
BOM:
the current BOM has few failures, a new Version is on the way.
for backup reasons, the old BOM:
the Resistor network designator/amount is wrong in the BOM.
Usermanual from APOB:
Costs:
case and PCBs 1250€
plus import/VAT 22%
mouser, digikey, tme 300€
eBay z80 and rare parts 50€
keyboard icon i-keyboard 4x 130€
Usermanual :
https://www.virtual-music.at/en/client/documents/OScar_UsersManual_VM.pdf
known issues:
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ID | Issue | Fix | date | fixed version |
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1 | traces are very close to the standoffs, which can in worst case make electrical shorts affect the joystick pcb
| use tape under the standoffs
| 12/2025 |
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2 | Quality Check cable | you have to check all cables and pinouts against the pcb silkscreen. (2 headers on my controlboard build are 180degrees rotated against the silkscreen - so I changed the wiring)
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3 | Quality Check soldering | check for solder bridges, check for missing or defect solder points |
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4 | Quality Check IC orientation | its important to avoid a wrong position, wrong orientation, bended Pins, |
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5 | Quality Check power | before you connect the PSU to the controlboard - measure -15/15V at the PSU out |
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6 | calibration | in case the sound is modulated - you have to calibrate the joystick “ function by: rotate the joystick in circles while turning on the device. The battery must be connected to the device /full or the “failure” is present on every restart of the device. |
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7 | important usage | as described in the user manual , the Trigger jack is for in and out : RING = Trigger Out , Tip = Trigger in |
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The DIY Kit contains the Case, Knobs, Potentiometers, Screws.
Note: remove on nearside of the ICON the screws, take the big screws at the side - you need them later !
The Synthesizer is basically digital based, the heart is the Processorboard with a Z80CPU and tons of ICs.