PROPHET64 & MSSIAH Userforum

austingecko · 2008-04-16 03:35:00

I've been using one of my R/C external 2-axis, 2-port controllers thus far and finally want to make the POT mods internal. Before I get to the confusing part it seems some people have connected the ground Pin 8 and others have not. Is there any consensus as to which is preferred or better? I'm going to be using 4 identical 500k Linear pots fyi. Also I've read if I put a toggle switch between pin 7 I can enable/disable this mod altogether. Can I route both pin 7's from each port to one switch?

Also, one of these 2 POT Mod Pin Diagrams seems to be backwards or at the very least misleading. One shows pin 5 on the right and one shows it on the left which is confusing. Can someone please clarify this? If both diagrams show the DSUB 9-pin connector from the OUTSIDE OR EXTERNAL to the case then one is backwards.

UNLESS GETLOFI's diagram is a diagram of the C64 system board from the bottom. This is the only way I can make sense of this when comparing to Firestarter's diagram which seems to be labeled as looking at the 9-PIN DSUB connector externally from outside the C64. Is this assumption correct? If so, this diagram needs to be modified to include better descriptions and the labeling of Port 1 and Port 2 would also be helpful.

FIRESTARTER MOD DIAGRAM

GETLOFI MOD DIAGRAM

Last edited by austingecko (2008-04-16 03:45:52)

Kartoshka · 2008-04-16 12:31:17

your assumption is correct.

austingecko wrote:
this diagram needs to be modified to include better descriptions and the labeling of Port 1 and Port 2 would also be helpful.

here's your chance, AG!

gelofi shows you he actual, bottom Soldering Side of c64 MB.

firestarter shows you external pins of assembled c64 (if you test the mod via normal DISASSEMBLED 9-sub connector for example, before soldering)

same pins shown to you.
just get a multimeter in hand, and try them yourself.

pin 7 is the ground on both ports.

austingecko · 2008-04-16 19:21:24

Thanks Kartoshka! I will work on making a revised diagram to share with everyone.

Are you sure Pin 7 is the ground? The diagram I found online shows pin 8 as the ground. Pin 7 is listed as the +5V. Which leads me to my other question--some people are connecting the ground and some are not. Is one method preferred over the other?

Thanks again for your help.

Last edited by austingecko (2008-04-16 19:27:49)

Kartoshka · 2008-04-16 20:49:00

you cought me ...
pin 8 is the ground.
pin 7 is the +5v - and if you put between'em a momentary (always off) switch, it will function as reset button.

firestARTer · 2008-04-16 20:53:56

Some people don't connect the ground cause it is not as originally specified.
I am not sure, but both are working i think.

ACrIkeD · 2009-06-07 19:23:48

Yep Pin 8 is a ground and it determines the 0 value of the knob.

The current knob you made works too but it has less range than the one with connection to ground.

However the schematic shown in page 25... I can do nothing but say that connecting Pin 7 to pin 8 even with a knob can smoke your system up.
I agree with your concern in this matter.

The C64 pin 5 and 9 can connect to knob center ( Pin 1 ) while pin 7 ( Vcc +5V ) is connected to knob ( Pin 2 ) and pin 8 is connected to knob side ( Pin 3 ).
Then the potentiometer works as voltage divider from range of 0V to 5+.

Your knob schematics do also work. Knob works also as variable resistor from 0Ohm to 500k Ohm, U = RI ( V = Ohm * A )
If R changes so does U that is what is measured in C64. Yes it works however it does consume a bit more current to work.

Last edited by ACrIkeD (2009-06-07 19:26:35)

PROPHET64 & MSSIAH Userforum

#1 2008-04-16 03:35:00

Confused when looking at 2 POT Mod Diagrams Floating Around

#2 2008-04-16 12:31:17

Re: Confused when looking at 2 POT Mod Diagrams Floating Around

austingecko wrote:

#3 2008-04-16 19:21:24

Re: Confused when looking at 2 POT Mod Diagrams Floating Around

#4 2008-04-16 20:49:00

Re: Confused when looking at 2 POT Mod Diagrams Floating Around

#5 2008-04-16 20:53:56

Re: Confused when looking at 2 POT Mod Diagrams Floating Around

#6 2009-06-07 19:23:48

Re: Confused when looking at 2 POT Mod Diagrams Floating Around

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