Re: hi res pic of 2001-8 power supply smoothing cap wiring

If it's long enough I suppose they could have run a separate ground wire to the metal monitor case as they did on some of the later models.
  ----- Original Message ----- 
  From: Santo Nucifora 
  To: cbm-hackers_at_musoftware.de 
  Sent: Thursday, November 07, 2019 6:28 PM
  Subject: Re: hi res pic of 2001-8 power supply smoothing cap wiring






  On Thu, Nov 7, 2019 at 6:11 PM Mike Stein <mhs.stein_at_gmail.com> wrote:

    "I checked 8 2001-8s from 10051 to 41072 from 4 wire in the earliest to 6 wires in the latest."
    -------------------------------------------------

    Curious; any idea what the 6th wire is for? I've only seen 4 or 5 wires.

  Mystery solved for me.  The fourth black wire goes nowhere :)  This is a PET 2001-8 Professional computer at serial 41072 which is pretty late, i think.



  http://vintagecomputer.ca/wp-content/uploads/2019/11/Pet-2001-PS-wiring-03.jpg





    It's pretty straight forward; the two brown wires (transformer terminals 4 & 6) are the 16V AC or so that go to J8 pins 1 and 5; terminal 5 (centre tap and ground) on the transformer goes to the negative cap terminal and from there to pin 3 and also optionally to chassis ground (all black).

    Pin 4 is rectified unfiltered 8V DC from the PC board and goes to the positive cap terminal and from there back to the board filtered on pin 2, both red. Accessory boards with on-board regulation often connect here.

    Note that the plug J8 can plug in either way.

    Keep the J8 pins clean; it is notorious for overheating and burning the pcb if it gets some oxidation etc. that increases contact resistance.

    m

      ----- Original Message ----- 
      From: Santo Nucifora 
      To: cbm-hackers_at_musoftware.de 
      Sent: Thursday, November 07, 2019 4:50 PM
      Subject: Re: hi res pic of 2001-8 power supply smoothing cap wiring


      I checked 8 2001-8s from 10051 to 41072 from 4 wire in the earliest to 6 wires in the latest.  I can confirm all blacks are on one terminal and all reds on the other.




      On Thu, Nov 7, 2019 at 4:42 PM Bill Degnan <billdegnan_at_gmail.com> wrote:

        http://vintagecomputer.net/commodore/2001-8/2001-8_sn20343.jpg



        20343


        I too have black wire(s) on the filter cap as you describe coming around from an unseen origin.  Is it as simple as all of the red so on one side, black on the negative? I am looking through what I have for the schematics for this model, until then I am just guessing.


        Bill


        On Thu, Nov 7, 2019 at 4:36 PM Santo Nucifora <santo.nucifora_at_gmail.com> wrote:

          I also have another model of 2001-8 that has an extra black wire clustered with the other black wires on the filter cap.  It goes to the power socket under the transformer so I can't see where it goes but I would assume the negative terminal?


          What is your serial number range?  The one I took pics of was 100895 so that one is kinda early.




          On Thu, Nov 7, 2019 at 4:27 PM Bill Degnan <billdegnan_at_gmail.com> wrote:

            Unfortunately I don't think we have the same model, here is what I have not mine but same transformer)
            http://www.8bit-homecomputermuseum.at/repair/bluepet/bluepet.html 


            Bill 



            On Thu, Nov 7, 2019 at 4:18 PM Bill Degnan <billdegnan_at_gmail.com> wrote:





              On Thu, Nov 7, 2019 at 3:46 PM Ville Laustela <ville.laustela_at_gmail.com> wrote:



                Here are two crops from my old photos, perhaps these are of some use:
                https://postimg.cc/VSR5yLqp
                https://postimg.cc/GHW4Gf37


                —
                Ville




              These photos are from a newer model, but thanks anyway.
              Bill