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#1 2010-05-29 19:27:47

oliq
Bloody beginner
Registered: 2010-05-29
Posts: 7

Blank Screen when pots installed

I've wired up 4 pots as per this diagram: http://www.getlofi.com/uploaded_images/Prophet64PotMod-766055.JPG

When I turn the machine back on I just get a blank screen (black). Strangely when I remove the pots the c64 works fine.

Any ideas how I can sort this?

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#2 2010-05-29 22:38:07

DjFluorescent
Space Invader
From: Texas,USA
Registered: 2010-01-16
Posts: 136

Re: Blank Screen when pots installed

Are you ABSOLUTELY sure you have the connections correct? I ask this because this particular diagram doesn't show the numbers of the pins, and you could have easily got things backwards.... you need only be using pins 5,7,8, and 9.


**** COMMODORE 64 BASIC V2 ****
64K RAM SYSTEM  38911 BASIC BYTES FREE.

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#3 2010-05-30 13:46:57

oliq
Bloody beginner
Registered: 2010-05-29
Posts: 7

Re: Blank Screen when pots installed

Yes, def got them right, I've checked about 3 times and continuity tested pins from the back of the board to the actual port. =s

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#4 2010-05-30 15:04:44

DjFluorescent
Space Invader
From: Texas,USA
Registered: 2010-01-16
Posts: 136

Re: Blank Screen when pots installed

You might need scooby doo for this mystery.... I'm stumped


**** COMMODORE 64 BASIC V2 ****
64K RAM SYSTEM  38911 BASIC BYTES FREE.

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#5 2010-06-06 20:58:30

ACrIkeD
Bomb Jack
From: Finland
Registered: 2009-06-05
Posts: 30
Website

Re: Blank Screen when pots installed

Because that shematic is wrong.


D-E03 - ( Deep Electronic 03 ) Experimental Electronic Engineering. Digital audio sounds like a grand old woman falling down the stairs.

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#6 2010-06-06 20:59:33

ACrIkeD
Bomb Jack
From: Finland
Registered: 2009-06-05
Posts: 30
Website

Re: Blank Screen when pots installed

Pin#/Cable Color/Function

Pin 1.      White.              Up ( Tact Switch )............................................
Pin 2.      Yellow.             Down ( Tact Switch )........................................
Pin 3.      Green.             Left ( Tact Switch )...........................................
Pin 4.      Brown.             Right ( Tact Switch )........................................
Pin 5.      Gray.               Y Vertical ( Acceleration Knob 475k / 500k )......
Pin 6.      Red                  Function / Fire ( Tact Switch )............................
Pin 7.      Blue.                Emiter +5 / Vcc ...............................................
Pin 8.      Black.              Collector / Ground?..........................................
Pin 9.      Purble.             X Horizontal ( Cycle Speed Knob 475k / 500k )


All the Tact Switches were connected to Pin 8.
When you pressed the tact switch it simply connected the source Pin(1,2,3,4,6) to Pin 8

All acceleration potentiometres took power from Pin 7. Pin7 to  Knob Pin2. 
Pin 5 or 9 were connected to Knob Pin 1. ( Center )
Knob Pin3. Return was to Pin 8.

Knob Pin* The pin number given to knob shematics.

C64
\ O1  O2  O3  O4  O5 /
\  O6  O7  O8  O9  /

Some usefull information I guess.


D-E03 - ( Deep Electronic 03 ) Experimental Electronic Engineering. Digital audio sounds like a grand old woman falling down the stairs.

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#7 2010-06-06 21:03:53

ACrIkeD
Bomb Jack
From: Finland
Registered: 2009-06-05
Posts: 30
Website

Re: Blank Screen when pots installed

Check your wiring. There is a bug.


D-E03 - ( Deep Electronic 03 ) Experimental Electronic Engineering. Digital audio sounds like a grand old woman falling down the stairs.

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#8 2010-06-06 21:05:26

oliq
Bloody beginner
Registered: 2010-05-29
Posts: 7

Re: Blank Screen when pots installed

Thanks for your help, but I find that really confusing. Any change you could do a diagram to help me understand?

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#9 2010-06-06 21:16:45

ACrIkeD
Bomb Jack
From: Finland
Registered: 2009-06-05
Posts: 30
Website

Re: Blank Screen when pots installed

The Diagram is wrong because.

Pot 1. Is controlling Joystic Down Button Pin 2. ( Instead of pin 5.)
Pot 2. Is controlling Joystick UP Button Pin 1. ( Instead of pin 9. )
Pot 3. Is controlling Joystick Down Button. ( Instead of pin 5. )
Pot 4. Is controlling Joystick UP Button. ( Instead of pin 9 )

Eh. No wonder things go smoking.


D-E03 - ( Deep Electronic 03 ) Experimental Electronic Engineering. Digital audio sounds like a grand old woman falling down the stairs.

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#10 2010-06-06 21:22:04

ACrIkeD
Bomb Jack
From: Finland
Registered: 2009-06-05
Posts: 30
Website

Re: Blank Screen when pots installed

Move the pot 3 dark green wire - "3 steps up" to pin 9.
Move the pot 4 light green wire - "4 steps up" to pin 5.

The same thing to other port.


D-E03 - ( Deep Electronic 03 ) Experimental Electronic Engineering. Digital audio sounds like a grand old woman falling down the stairs.

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#11 2010-06-06 22:13:52

oliq
Bloody beginner
Registered: 2010-05-29
Posts: 7

Re: Blank Screen when pots installed

Thanks, I'll give that a try- seems odd that other people have got it to work using that diagram if the pins are totally wrong as you say. Certianly didn't work for me that way though!

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#12 2010-06-12 00:03:24

Hesed
Wonderboy
From: Dd/Pa
Registered: 2006-11-10
Posts: 173
Website

Re: Blank Screen when pots installed

sorry ACrIkeD but the schematics are right because are meant from the back of the c64 board so if you sold directly on the board.

So the pin are correct as you says, again no solution on burned c64!

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