CPC 464 - German -Schneider config

[JuergenBobo]

HI!! I have an CPC464 - German from Schneider. 
If I switch it on I can see the welcome screen , but the vertical sync seems to be incrorrect. I have done some measuremeants and I have no glue what it can be. It's an PT No.  Z70200 / MC0002B

MC6845P - vsync and hsync seems to be ok 
Gate Array - I test this chip in a different board and it works there!
RAMs - seems to be ok

I get the impression the 16MHZ clock didn't look nice. I would expect an nice square wave; but get more something like a saqtooth. But the system seems to work otherwise I wouldn't get the welcome screen (yellow text on blue).

Some additional information the z80 come from MOSTEK !! Yes, the 6502 supplieres. I know they produce Z80, too. But was surprised to see one. If you look the back side of the board ... it looks strange I get the impression it was solded completet by hand. Soldering point looks partial , well not nice. Distributed over the complete board. 

Any hint for the sync issue would be nice!


saludos
  Juergen

[eto]

is it original monitor? did you try to adjust the v-hold screw at the backside of the monitor?

[robcfg]

Hallo Juergen!

Can you post some pictures of the board? To see if it's been modified.

A short video of the problem would be good too.

Cheers,
Rob

[SkulleateR]

Mostek had a license to manufacture Z80 CPUs from Zilog 

[Prodatron]

the z80 come from MOSTEK !! Yes, the 6502 supplieres.

Maybe you are mixing up Mostek with MOS Technology. These are two completely different companies.
Mostek was the first, who produced Z80 cpus at all (before Zilog had its own fab). They never produced the 6502.

[JuergenBobo]

Thanks for the feedbacks ...

1. No I have no orginal monitor I use an old Thomson monitor which shows a perfect picture on my second CPC. Input is a SCART cable.

2. Yea possible I mixed MOSTEK and MOS ... sorry my fault. 

3. Board pictures are attached ... video I can send later.

thanks
 Juergen

[Bryce]

HI!! I have an CPC464 - German from Schneider.
If I switch it on I can see the welcome screen , but the vertical sync seems to be incrorrect. I have done some measuremeants and I have no glue what it can be. It's an PT No.  Z70200 / MC0002B

MC6845P - vsync and hsync seems to be ok
Gate Array - I test this chip in a different board and it works there!
RAMs - seems to be ok

I get the impression the 16MHZ clock didn't look nice. I would expect an nice square wave; but get more something like a saqtooth. But the system seems to work otherwise I wouldn't get the welcome screen (yellow text on blue).

Some additional information the z80 come from MOSTEK !! Yes, the 6502 supplieres. I know they produce Z80, too. But was surprised to see one. If you look the back side of the board ... it looks strange I get the impression it was solded completet by hand. Soldering point looks partial , well not nice. Distributed over the complete board.

Any hint for the sync issue would be nice!


saludos
  Juergen

Unless you have an extremely expensive scope you will not see anything close to a square wave 16MHz clock.

Bryce.

[GUNHED]

is it original monitor? did you try to adjust the v-hold screw at the backside of the monitor?

Just had exactly the same idea.