• Please review our updated Terms and Rules here

First Commodore PET in Ukraine :)

M

monoxrom

Experienced Member
Joined
Apr 5, 2009
Messages
139
Location
Ukraina
Hello!
Please help me with Commodore PET 4016 computer..
I was buy this item on ebay. He was in bad shape but cheap.
I cleaned dust, wasp nest and made redecoration. Replace some electrolytic capacitors.
Today I have included it and heard the "greeting sounds" from beeper
But nothing on the screen :(

I would ask, how many volts should be a power of monitor? Because i have 5 volts on power transformtaor. I think this is not enough, yes?

And next some strange capacitor in monitor board. You can see him on 4 picture.
This capacitor is electrolytic but don't have polarity? Can i replace it to normal capacitor?
 

Attachments

  • p1.jpg
    p1.jpg
    91.6 KB · Views: 3
  • p2.jpg
    p2.jpg
    62.9 KB · Views: 3
  • p3.jpg
    p3.jpg
    72.3 KB · Views: 3
  • p4.jpg
    p4.jpg
    56.5 KB · Views: 3
My working 4016 has 21.5v going to the monitor (12" display), but is hooked up to 11 and 9 on the transformer. I checked my transformer and I also have +5 AC from pins 11 and 10.

So move the wire from terminal 10 to terminal 9, and then if you get nothing, check for output on the monitor connector J7.

The pin numbers go from left to right, with pin 2 missing as the key.

Using a meter set to DC you should see voltage on pins 3 and 5, if these are missing, you will not get the monitor to power up.
Here's a link to the schematics.

http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/univ/8032081-10.gif

Good luck!

Later,
dabone
 
Thank you dabone!
Computer starting! But new problem - keyboard not working :(
Maybe i need to clean keys contacts, but all keys not working? strange...
 

Attachments

  • p5.jpg
    p5.jpg
    49.7 KB · Views: 2
Take the keyboard apart and clean all the contacts on the circuit board with a eraser. I personally remove all the keycaps and scrub them in hot soapy water.
Makes a huge difference in appearance.

Later,
dabone
 
monoxrom said:
Thank you dabone!
Computer starting! But new problem - keyboard not working :(
Maybe i need to clean keys contacts, but all keys not working? strange...
Click to expand...
Congratulations!

Considering the amount of corrosion elsewhere it is indeed most likely that the keyboard needs a good cleaning; you might short out some of the row and column lines on the connector though, to confirm that it is actually being scanned.
 
Is the cursor blinking? If not, perhaps the PIA (6520) at UB2 is faulty. It generates the interrupt from the vertical drive signal on pin 18 of UB2 to blink cursor and read keyboard.
 
All ok with keyboard. Eraser and alcohol repaired all keys :)
Remains one question with capacitors. I still need to replace two standard capacitors in monitor
and one who don't have polarity.

I have received advice than i can replace nonpolar capacitor (12 mf 25v) like in this scheme (attached)
This advice is true?
 

Attachments

  • post.jpg
    post.jpg
    12.9 KB · Views: 1
You must log in or register to reply here.
Back
Top