NEC PC-6001 MK II

[tomeucapo]

Hello at all!

Recently I acquired old NEC PC-6001 MK II japanese microcomputer based on Z80. I try to figureout what is issue on microcomputer because when power-up computer the screen garbage appears and do nothing else. Screen of columns of 9 on whole screen.
I start try to figureout issue, checking all RAM ICs, some glue logic TTL ICs, Z80 processor, but I don't had any detailed schematics of that board. I tried to find on bitsavers or archive.org (only found user manual with very basic block diagram of computer).

I had bad news, because that model had some NEC custom ICs like video generator and NEC custom gate array that concentrate main glue logic

P.D.: I check all voltages +5, -12 and +12VDC are OK! All ROMs I readed and checked with my EEPROM programmer check with original image CRC and are equal.

Any ideas? Somebody knows where to find detailed technical schematics?

Thanks for advance

 

[krebizfan]

There was a thread here from 8 years ago which included a link to schematics. https://forum.vcfed.org/index.php?t...the-old-nec-pc-6001a-around-here.59461/page-4
I don't know if there is a newer place for the schematics.
I know those do not refer to exact same model but maybe it will provide a starting point.

 

[zu2]

A quick search for “PC-6001mkII 修理” (in Japanese) brings up a lot of useful information. It looks like many video problems are due to shorted tantalum capacitors that have aged.

 

[tomeucapo]

A quick search for “PC-6001mkII 修理” (in Japanese) brings up a lot of useful information. It looks like many video problems are due to shorted tantalum capacitors that have aged.

Thanks! Its my first action to take, replace all tantalum caps!

 

[tomeucapo]

There was a thread here from 8 years ago which included a link to schematics. https://forum.vcfed.org/index.php?t...the-old-nec-pc-6001a-around-here.59461/page-4
I don't know if there is a newer place for the schematics.
I know those do not refer to exact same model but maybe it will provide a starting point.

Thanks for information, but i try to find any info on our forums and found also that thread but 6001A is totally different that 6001 MK II. 6001A had all glue logic with TTL ICs and MK II use some NEC custom ICs to do glue logic and VDP.

 

[zu2]

Thanks for information, but i try to find any info on our forums and found also that thread but 6001A is totally different that 6001 MK II. 6001A had all glue logic with TTL ICs and MK II use some NEC custom ICs to do glue logic and VDP.

There is a reverse-engineered schematic of the PC-6001mkII available here:

mk2回路図(1): Ｐ６つくろうブログ

mk2回路図(1): Ｐ６つくろうブログ

The “.CE3” extension appears to be from a Japanese schematic editor called bsch3v:

水魚堂の回路図エディタ

Hope this helps!

 

[tomeucapo]

There is a reverse-engineered schematic of the PC-6001mkII available here:

mk2回路図(1): Ｐ６つくろうブログ

mk2回路図(1): Ｐ６つくろうブログ

The “.CE3” extension appears to be from a Japanese schematic editor called bsch3v:

水魚堂の回路図エディタ

Hope this helps!

Awesome! Is better than nothing
Now I continue to figureout where is the issue with schematics better!

Thanks for all