README.md
KU-14194HB-RevB-KiCad




The rare KU14194HB C64 Motherboard schematics and layout. Retraced in and imported from SprintLayout.

Disclaimer: See DISCLAIMER.md

Original bodges

This PCB is a replica. It includes the mistakes that Commodore made.

It is necessary to cut a trace above R37 on the bottom side, and add a 1K resistor from R37 and up to a via.
See the images folder to where to cut and add a resistor.

Piggyback a 100nF capacitor over CR1.

Notice how the main crystal oscillator Y1 body is grounded with a wire.

In later designs 250407 Reb B I think, 4 piggybacked diodes were introduced to protect the serial lines when hotplugging the disc drive.
I haven't added these myself, but I see the value of having those. I might add instructions here later on how to add the diodes.

Questions


Feel free post questions in the issues section. I will provide more information here later.


BOM

I'm working on it. I've started on a bom with Mouser and Reichelt part no.

Change log


2020-01-23: V1.4 PCB improvements:


Expansion Port: Larger round solder pads for the shield. Same error in the original.
Expansion Port: Connector moved to center of shield. Some traces moved.
Left edge: Extended the PCB by 2.2mm.
Left edge: Increased track width of the power rails.
CAN shield: added two solder pads.
RF modulator: added solder pad.
Schematics: Rev 1.4. No change.

2019-11-12: V1.3 Fixes: Mostly missing values.


C88: "1000uF 25V" -> "470uF 50uF". Commodore said 1000 but used 470.
R31: "180" -> "1K". A mistake in the commodore schematics.
R52: "?" -> "330"
R53: "?" -> "100"
C86: "?" -> "82pF",
C36: "0.1" -> "20pF",
R22: missing trace. R22 = 0 Ohm. Parallel to C87 (NC). R22 doesn't matter.
C101: is a Y5U. VIC2's decoupling cap. Has a higher dielectric rating. Doesn't matter.
C70: 15pF 5%. This is a PAL only board. In later revisions, 16pF is used for NTSC.
2019-11-10 V1.2 Added missing C14 10uF 25V electrolytic capacitor

2019-10-15 V1.1 Layout: Fixed missing keying-slot in user port.
2010-10-05 V1.0 First release.


YouTube

A playlist of all the videos:

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In the wind

forum64.de: The board has some threads at forum64.de (German). May require login.
* ]]>KU-14194 Bestückungs-Thread]]>
* ]]>KU-14194]]> (long group buy thread)
* ]]>KU-14194 (Replika) ... wer schafft es als Erste/r? Aktuelle Sachstandsberichte ...]]>