Research an electric schematic of the mother board for msx vg-8020

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By RetroTechie

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21-04-2010, 21:11

... and VG8235.
or NMS8220: looks like the 8020, but with darker gray colored case (more stylish IMHO), and is MSX2 but without built-in floppy drive.

By Leo

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21-04-2010, 21:15

Hi, in the case bottom is whoten vg8235/00 , but over the black cover' s slot-cartrige it's whoten vg8020: i think than the real name of the mother board is vg8020.
The color of case is silver, the color of the keyboard is black and its house production is philips.
Leo, what's your opinion ?

if your msx has not a disk drive than it is vg8020 .
it could be also a vg8220 (early msx2 that looks like msx1 , but quite rare ?

look this link which photo is the closetsto yours ? first ? second ?

http://msx.fab.free.fr/msx2/philips/philips.htm

By sp4

Master (214)

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21-04-2010, 21:58

Leo, my photo is the first and my VDP is TMS-9129.
Jipe, can you send me your vg8020/00 schematic at newbie75@libero.it ?
Thank you very much.

By RetroTechie

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21-04-2010, 22:24

Leo, my photo is the first and my VDP is TMS-9129
Okay, so that makes it an MSX1 (VG8020). Now: does it have a big surface-mount IC marked S3527 inside, or does it have some separate IC's marked 8255 (40-pin), and GI AY-3-8910 / Yamaha YM2149 (also 40-pin) ?

By sp4

Master (214)

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21-04-2010, 22:38

In opposit side of Z80 there is only the IC Yamaha s-3527.
It's a surface-mount IC quad in line.
Have you any schematic about it please?
It hasn't 8255 and other Yamaha chips.

By RetroTechie

Paragon (1563)

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21-04-2010, 22:54

In that case I think you're out of luck... what you'll have is a later model 8020, probably the VG8020/20 or VG8020/40 (are you sure the label on case bottom says "vg8235/00" Question). There is a schematic online for the 8020, but you'll find it's of the VG8020/00. Very different mainboard, so its schematic will be of limited use to you.

I suggest you grab schematics for the VG8020/00, and the NMS8220 here, and do some checking on your computer's mainboard to find out how the clock signal is routed exactly. Also the S3527 datasheet may come in handy.

P.S. Are you sure it's worth the trouble to repair an MSX1, especially a common/cheap model like the Philips 8020? I sure as hell wouldn't bother unless I was certain it's a 10 minute job... :hannibal:

By sp4

Master (214)

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21-04-2010, 23:06

I've never repaired an msx: it's the first time for me, but i've all elettronics tools and instruments for have the repairing.
I want to try, but i need absolutly the schematics.
RetroTechie, can you send me vg8020/00 schematics and other two version?(vg8020/20 and vg8020/40)
I want watch all three version for compare the difference.

By RetroTechie

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22-04-2010, 00:01

Click the link above for VG8020/00 service manual... Tongue I also have service manual for VG8020/20, but unfortunately in dead tree format only. The missing info you'll need is S3527 pinout, you can find this in S3527 datasheet or other service manuals. If you're going to repair it, exact routing of the clock signal is something you'll have to check anyway, schematic or not.

The only significant difference in 8020 models is S3527 vs. discrete 8255 PPI + soundchip (and maybe ROM contents for different country versions?). AFAIK differences between 8020/20 and 8020/40 are very minor, if any.

By Jipe

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22-04-2010, 18:15

sorry the only schematic of VG8020 is for a 00 and have not S3527 but you can inspire to VG8235/00 for the MSX engine part

By Leo

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24-04-2010, 14:08

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