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Ohio Scientific Challenger 1P Mods

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  Ohio Scientific Challenger 1P Mods by Bill Degnan - 01/08/2020 17:46
This OSI Challenger 1P came to Kennett Classic as a donation. It has some interesting mods installed including a "BREAK/No BREAK" mod and a "Tape" mod. Click image for larger view.


A "Sup-R-Mod" has been installed so that the computer can be attached to a black and white television on channel 33. Not any TV will work, only the old style sets without a certain type of synch (forget the details) such as the pictured Sony PVJ-51RU I picked up from a computer rescue last year. Click image for larger view.


NEXT: Open the system and work through the mods, try to find matching documentation, tweak and test. The BREAK/No BREAK works (prevents accidential softboot). I have not yet attached a cassette to the system. Stay tuned.

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  Detailed MOD Photos by Bill Degnan - 01/10/2020 12:28
Ohio Scientific Challenger 1P mods
Here's a nice view of the BREAK/NO BREAK wiring and toggle activation switch. With this MOD, one can disable an accidental softboot caused by pressing the BREAK key on the keyboard. Click image for larger view.


BREAK mod pic2
BREAK mod pic3

Ohio Scientific Challenger 1P mods
Here's the view from the underside mid-board edge conenctor. From this angle one can see the TAPE toggle (bottom right) and to the left of the large circular fan opening, the serial port. (Follow the purple/blue/green wires) Click image for larger view.


wiring pic2

Ohio Scientific Challenger 1P mods
Pictured is a view of the mod wiring from the underside of the the corner edge connector. From here you can see the SUP-R-MOD RF adapter, video port and cassette ports. Click image for larger view.

wiring pic4
wiring pic5
wiring pic6
wiring pic7
wiring pic8
wiring pic9

More photos (full motherboard, power, etc.)

NEXT: I should have most of the schematics, or I can pretty easily plot out the circuits for these mods for support purposes. One would have read articles describing these mods, with schematics, from old magazines like 6502 journal or MICRO, Kilobaud, etc.

When I get the chance I will post more info if I discover something useful that is not already out there.

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