BobbinThreadbare
Member
Hi folks,
Up for sale today: a PAL VIC 20 CR / cost reduced (C64 PSU compatible) motherboard in need of repair.
Asking £10 plus postage and paypal fees.
The board either boots to a black screen or graphical corruption. Running dead test+ shows that "RAM 0" and the colour RAM (i.e. all three 2114 SRAM chips) and the character ROM are bad. RAM 0 tests as bad consistently but the bits that are flagged as bad vary - sometimes only 1 bit, sometimes all 8. The colour RAM and character ROM are always flagged as bad.
Note that none of the chips that are flagged as bad are in sockets and the board has obviously been repaired before as (for example) only 1 of the 6522s is in a socket, the other is soldered directly to the board and all three 2114 chips are different. I'm not an expert but judging by the back of the board I think these may have been factory repairs / Commodore randomness?
When I got the board one of the VIC chip pins was bent. I've straightened the pin and put the chip in a turned pin socket so that if you need to remove the chip from the board you can lever it out using the socket without worrying about bending that weak pin again.
Photos:
Typical (non-black) boot screen (character corruption varies):
Whole board:
Bad SRAM chips - UD2, UE2, UE1 and bad character ROM - UD7
Video of dead test+ run - 2 mins long, switches from corrupted character ROM to RAM font at 1:08
https://photos.app.goo.gl/wTKCN8W2pzAgDpqq8
Dead test+ reference:
http://blog.tynemouthsoftware.co.uk/2019/02/vic20-dead-test-plus.html
Up for sale today: a PAL VIC 20 CR / cost reduced (C64 PSU compatible) motherboard in need of repair.
Asking £10 plus postage and paypal fees.
The board either boots to a black screen or graphical corruption. Running dead test+ shows that "RAM 0" and the colour RAM (i.e. all three 2114 SRAM chips) and the character ROM are bad. RAM 0 tests as bad consistently but the bits that are flagged as bad vary - sometimes only 1 bit, sometimes all 8. The colour RAM and character ROM are always flagged as bad.
Note that none of the chips that are flagged as bad are in sockets and the board has obviously been repaired before as (for example) only 1 of the 6522s is in a socket, the other is soldered directly to the board and all three 2114 chips are different. I'm not an expert but judging by the back of the board I think these may have been factory repairs / Commodore randomness?
When I got the board one of the VIC chip pins was bent. I've straightened the pin and put the chip in a turned pin socket so that if you need to remove the chip from the board you can lever it out using the socket without worrying about bending that weak pin again.
Photos:
Typical (non-black) boot screen (character corruption varies):
Whole board:
Bad SRAM chips - UD2, UE2, UE1 and bad character ROM - UD7
Video of dead test+ run - 2 mins long, switches from corrupted character ROM to RAM font at 1:08
https://photos.app.goo.gl/wTKCN8W2pzAgDpqq8
Dead test+ reference:
http://blog.tynemouthsoftware.co.uk/2019/02/vic20-dead-test-plus.html
Last edited:
