CPC 464 black screen - LED on - no beep

[McArti0]

300Hz 

Now you need to know one thing.
The program that is in the ROM at the very beginning configures the CRTC and GA. If you want to see how the CPC works, functional but not configured. You can turn off the ROM by applying +5V to ROMDIS. (Pin22 ROM IC103 or top end R112). And turn On CPC

[willow3411]

300Hz 

Now you need to know one thing.
The program that is in the ROM at the very beginning configures the CRTC and GA. If you want to see how the CPC works, functional but not configured. You can turn off the ROM by applying +5V to ROMDIS. (Pin22 ROM IC103 or top end R112). And turn On CPC

OK thanks 
I will test this
For now I would like to understand and above all make my motherboard which has a black screen work.
ps: I confirm that I have 250Hz on pin14 of the GA
what can I do now?
I am disappointed...

[McArti0]

For now you are gathering knowledge to understand what you are doing.

You fixed the clock. You started CRTC and GA. Now you know that Z80 does not execute configuration code from ROM.

[willow3411]

For now you are gathering knowledge to understand what you are doing.

You fixed the clock. You started CRTC and GA. Now you know that Z80 does not execute configuration code from ROM.

yes

what I mean is that the measurements taken just before come from my functional motherboard

[willow3411]

For now you are gathering knowledge to understand what you are doing.

You fixed the clock. You started CRTC and GA. Now you know that Z80 does not execute configuration code from ROM.

yes

what I mean is that the measurements taken just before come from my functional motherboard

Hi,
I,m burned eeprom rom 40009 . It's not ok ....
Sorry i'm with m'y phone....
Willow

[willow3411]

@Bryce 
@McArti0 

now we should test the ROM right?
Do you want the measurements of the faulty motherboard?
THANKS

[McArti0]

Do you have a ROM programmer and can you check the correctness of the input in it? 

[willow3411]

Avez-vous un programmateur ROM et pouvez-vous vérifier l'exactitude de l'entrée qu'il contient ?

oui j'ai un programmateur t48. j'ai déjà flashé un 40009 mais ça ne marche toujours pas.
je dois le tester avec le programmeur ?

[McArti0]

Some device must tell you that the ROM contents were burned successfully.

[willow3411]

Some device must tell you that the ROM contents were burned successfully.

yes it is. no worries on that side

[willow3411]

anyway I even have a diagROM.
and even with it I have black screen.
Also with my Dandanator black screen.

[Bryce]

If that's the case, then something else is permanently holding an Address or Data bit high or low. Use the scope to see if there is any bit on those buses that never changes.

Bryce.

[willow3411]

If that's the case, then something else is permanently holding an Address or Data bit high or low. Use the scope to see if there is any bit on those buses that never changes.

Bryce.

hi @Bryce 

hi,
Which Buses do you want to talk about?
the frequencies measured on the GA, the Z80 and the CRTC?
is that right?
THANKS

[McArti0]

Lines D0,D1,D2...D7 at z80, 8255 or crtc.
And A0,A1.... A15 z80

[willow3411]

Lines D0,D1,D2...D7 at z80, 8255 or crtc.
And A0,A1.... A15 z80

hi @McArti0 ,

Ok so if I understood correctly the frequency must not be the same at each measurement (3 times in a row is it good?)

thanks

[McArti0]

Not freq. Any Changes.

[willow3411]

Not freq. Any Changes.

No understand.... sorry....

[McArti0]

[willow3411]

heu....

humor ?...  

[McArti0]

Yes but no..
if you see flat line , that signal is suspect to be dead.

[willow3411]

Yes but no..
if you see flat line , that signal is suspect to be dead.

I understood everything