I promised a friend that i will give him a C64 from my collection.
He used to have a bredbin C64 (with swedish keys) back in the days, so i took one of those from my collection for this project.

When powered up, it gave me a blue screen with a blue border, nothing more.
The Jupiter Lander cart worked when i tested with that.
(It does not use the ROMs on the C64, so if that cart works it can be one of the ROMs that has failed.)
The suspected IC was the Basic ROM.
I took it out and soldered a socket in its place.
Inserting a Basic ROM from my parts bin solved the situation.
(I also had to replace the SID because it too did not work.)

Testing with my diagnostic cart and harness gave a positive result, all good.

I connected it to one of my cassette players from my collection and tried to load a game.
This did not work, but after adjusting the tape head i got it to work.
Tested another game and it was fine too.
(Tested a two player game and it works fine.)

A C64 with cassette player : Check!
Still to go is a working power supply and a video cable so he can hook it up.

It seems that a lot of people had noticed that the original psu has a tendency to fail, outputting much higher voltage that fries the C64 components.
For like ten years ago i modded a psu for my C64 that i am using with a 2.4A cell phone charger inside for the +5v, and keeping the transformer for the +9v AC.
I will do the same here.
Just open the psu, remove the original circuit used for the +5v, and install the cell phone charger circuit instead.
I will pick up a suitable cell phone charger on Monday that delivers about 2.4A.
(The original delivers 1.5A, so 2.4A is more than enough for the C64.)
To be continued… 🙂