Help fixing Vector-06c

[cyb2600]

Success! It now boots, but the colors seem inverted. The background is yellow and the lines are blue. I'll try connecting the resistors directly to the inverters as in the schematic, but last time I tried that I only got a white screen. I'll also try to load that test program, other RAM may possibly be bad. Thanks everyone for your help.

[KTSerg]

... I'll also try to load that test program, other RAM may possibly be bad. ...

Test RAM.
http://sensi.org/scalar/ware/649/

[cyb2600]

It looks like it found two more bad RAMs. D78 and D64?



Same result with second utility



EDIT: I replaced the two bad RAMs, it's booting fine now. I loaded a few games and they seem to work other than the colors being wrong.

EDIT 2: I rewired the resistors to the inverter as per the instructions and now I get a perfect picture.

[KTSerg]

...
EDIT: I replaced the two bad RAMs, it's booting fine now. I loaded a few games and they seem to work ...
EDIT 2: I rewired the resistors to the inverter as per the instructions and now I get a perfect picture.

Congratulations on your successful computer recovery.

Color test.
http://www.sensi.org/scalar/ware/770/

For what purpose did you buy this particular computer?

D9 - 556PT5 or 556PT7 ?
If 556PT6, then replacing the bootloader chip will significantly expand the ability to download programs (FDD, HDD, external RAM, external ROM, LAN, ... - you need special controllers).

[cyb2600]

D9 is a PT5, the 512 byte ROM. Are there instructions on how to upgrade this to a larger ROM? Since it uses two Chip Select lines I'm not sure if I could directly replace it with a 27256? I'd definitely like to use the "Combodevice" so I can load software faster and try out some Demos.

I used to collect old computers, and I bought this one and a BK-0010 off of E-Bay 10-15 years ago. I also got a "Nu Pogodi" Game & Watch clone and an Elektronika "Video 01" Pong clone. I don't recall how much I paid for them but they were pretty inexpensive back then. I wish I had bought an MK-85 back then when things were cheap. The BK-0010 worked fine but the Vector-06c didn't. Since I've been stuck at home during this quarantine I decided to finally fix it. In total 5 chips were bad - two flip flops and three DRAMs.

[KTSerg]

D9 is a PT5, the 512 byte ROM. Are there instructions on how to upgrade this to a larger ROM? Since it uses two Chip Select lines I'm not sure if I could directly replace it with a 27256? I'd definitely like to use the "Combodevice" so I can load software faster and try out some Demos.
...

I already gave a link to the instructions for replacing the ROM.
You can change it to any ROM, I wrote that now 27512 is installed on my computer, and previously I installed 290011. I installed a socket in the computer and change the microcircuit when necessary. I installed jumpers on the ROM, and several different programs were written into it at once.

cyb2600, write what kind of ROM you have, here they will tell you how to connect it.

[Advertiser]

[cyb2600]

I have blank 27256 and 27512, I can use either.

[KTSerg]

I have blank 27256 and 27512, I can use either.

There are a lot of options for improvement.

ROM pin mapping.
https://s8.hostingkartinok.com/uploa...b5d7c3d99c.png

I suggest installing a 28-pin socket on the board to install the ROM.
Pins: 1, 2, 20, 21, 23, 24, 27, 28 - bend the leads, do not solder them into the board, isolate them from the board contacts.
Connect pins 26 and 28 (A13 always "1").
Connect old pin 21 - new pin 20.
Connect new pin 21 and D1 pin 17 (A10).
Connect new pin 24 and D1 pin 18 (A9).
Connect pins 23, 2, 27 to jumpers to select a program (for 8 program of 2K).

Рrograms will need to be written to the ROM from the addresses:
A14="0":
2000h
2800h
3000h
3800h
A14="1":
6000h
6800h
7000h
7800h

It is not necessary to connect free address pins (23, 2, 27) with jumpers, you can connect them to the power supply or the case, and write only one program to the ROM.

The corner at the first contact of the socket will need to be cut, since chip D1 will interfere.

Поправьте описание доработки, если онлайн переводчик накосячил.

[svofski]

cyb2600, congratulations on restoration of your new awesome computer! I hope you're going to spend some quality time with it.

A friend of mine is developing a ROM adapter for tidy ROM replacement. It's a work in progress at the moment:
https://github.com/desaster/vector06c-rom-adapter

[cyb2600]

Thanks. The modification looks easy enough to do own my own, although the adapter certainly would be tidier. Is there a reason to load multiple BIOSes? Or do you put something else in the extra ROM space?