Commodore PET CBM 4016 ASSY 8032080 RIFA burn and more

[daver2]

The 4032...

I have now finished for the day - watching TV and vegetating!

Can we resume tomorrow?

As you have 2 banks of DRAM on the 4032, we can swap the banks over with two simple wire changes...

Dave

 

[DrAlis]

Sounds like a plan. Enjoy TV & chill

 

[daver2]

Sorry, I have got distracted today.

There is a fairly recent Commodore PET post that I made about swapping over the two banks of RAM - if you don't mind going hunting...

Dave

 

[Hugo Holden]

I made over 20 scope recordings of the DRAM support circuitry in this article pages 6&7, which might be a useful comparison if you are checking the DRAM support circuits with your scope:

www.worldphaco.com/uploads/DRAM%20MEMORY%20TEST%20SYSTEM%20FOR%20THE%20DYNAMIC%20PET%20COMPUTER.pdf

 

[DrAlis]

Awesome materials, Hugo! I ran out of spare time, so further analysis will be postponed some days and I shall report back. Dave, I looked for the relevant Post on bank switching but did not succeed so far.

 

[daver2]

I'll post a new schematic tomorrow.

Dave

 

[daver2]

First off, you need to find these two resistors (R41 and R42 - both 27 Ohms):



Find which end of the resistors that G7 pin 6 and G7 pin 12 connect to.

Dave

 

[daver2]

Disconnect ONE end of the identified resistors (R41 and R42).

In the image below I have identified that the ends connected to G7 be disconnected. You could choose the other side of the resistors if that is more easy.

Remove one end of each of the resistor leads from the board.



Dave

 

[daver2]

Cross-connect the resistor legs (that you have removed from the PCB) and the pads:



Dave