Commodore 64 8-pin video connector. Is there +5V or not?

[oracle_jedi]

Hoping someone knows this and has a quick answer, otherwise I am going to have to pull the 64s out of the closet and rig up a test.

 

 

I've seen at least 4 different pin outs of the C64's 8-pin din video connector.  

 

A +5V supply is shown variously on pins 8, 7, 5 and not at all.

 

I know very early 64s had the 5-pin connector.  Not talking about those.  Strictly regarding the 8-pin variety - is there a +5V supply and if so, where is it?

 

 

 

 

 

 

[+OLD CS1]

A good question.  The schematics for 250649, 250425, 250466, and 240441 show 5V at pin 8, while 250407-04 show N/C for pin 8.  I did not look any further.  Soooo, if these schematics match reality, then some models have 5V at pin 8, some do not.

 

Reference: https://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/

 

I would say that if you need 5V for an external device, get it from the cassette port like myriad components from the era do.

[hofster]

Beware that the pinout images you get if you do a web search have different pin numbering patterns. That's likely why you see contradictory information on which pin number is which signal.

[carlsson]

I wonder if this was a leftover from the 5-pin DIN connector on the VIC-20 which has 6V (or perhaps it is 5V) at maximum 10 mA intended to drive the RF modulator. Since the C64 has the modulator built-in, eventually perhaps they figured out there was no reason to route a voltage through the A/V port any longer.

[hofster]

I don't think so. 5V is on one of the top pins that don't exist on the 5 pin connector.

[hofster]

5 minutes ago, hofster said:

I don't think so. 5V is on one of the top pins that don't exist on the 5 pin connector.

Well, the general idea might well be a leftover from the VIC-20.

[oracle_jedi]

7 hours ago, OLD CS1 said:

A good question.  The schematics for 250649, 250425, 250466, and 240441 show 5V at pin 8, while 250407-04 show N/C for pin 8.  I did not look any further.  Soooo, if these schematics match reality, then some models have 5V at pin 8, some do not.

 

Reference: https://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/

 

I would say that if you need 5V for an external device, get it from the cassette port like myriad components from the era do.

 

Thanks for sharing that.

 

I am trying to replicate the work of @puppetmark and create a simple s-video/luma to RGB adapter, using an LM1881, so I get some more use out of my Atari SC1224 monitor.  I got a first version done, but I wanted to improve it by using an 8-pin din connector that works for both Atari 8-bits and Commodore 64/Plus4 machines.  If the Commodore has +5V on pin 8 then it wont need an external +5V which would be convenient.

 

I checked one of my C64s though and no +5V on pin 8

 

 

 

 

Edited May 13 by oracle_jedi

[+OLD CS1]

6 minutes ago, oracle_jedi said:

I checked one of my C64s though and no +5V on pin 8

If you are doing this just for yourself, it should not be a big deal to attach 5V to pin 8, provided it is N/C in your system.  If you are doing it for a wider range of users, then a lot of us would have no problems with doing the same.  Not as convenient as a single, all-in-one module, for sure, but still worth the effort for some.