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[Sinclair]

Ok.

I have tried to change the title of this thread because it isn't very descriptive but it is not possible.
 
Well, I am ruling out possibilities.
 
I have extracted the VIDEO ROM chip and tried to read its contents set up my programmer to read a 27c64/2764 but the programmer has not recognized the chip. However if I configure it as 2732/27c32 if I read it but the information does not seem complete.
Is this normal?
 
If not so, would, I tell someone where to get content of this ROM to burn it on another chip and follow with the tests?
 
The VIDEO ROM numbers are 341-0650-A
 
Thank you

 

[bibilit]

Miguel,

you can find the content here:

http://www.synack.net/~bbraun/roms/

Good luck.

 

[Sinclair]

Thank you.

Finally got to read the ROM as W27c256.
 
I Wrote a new EEPROM with the content of the chip and the linked file above and the problem persists, the ROM working fine.

 

[techknight]

the ROM isnt the issue, it never was... 

 

[Sinclair]

Was only for discat things and because I was bored ;D

 

[Sinclair]

One more question:

This issue is compatible with VRAM?

 

[Paralel]

Yep

 

[Sinclair]

Yep

okey!

I would like to confirm this before I have to unsolder the VRAM chips and having to buy new ones.
 
It seems that there is a software of diagnosis called "MacTest is / 30 '' (http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Companies/Apple/Documentation/Apple%20Technical%20Information%20Library/a2til197.txt) that it can help diagnose this problem.
 
The question now is where I can get this disk image.
 
Thank you.

 

[bibilit]

Miguel,

I think the software you are looking for is for the Apple TechStep tool... was supplied to Apple technicians, but is a rare beast today:

 

[Sinclair]

Thanx Luis

Is rare found it but I'm sure that anybody has preserved.

Other diagnóstic tool is wellcome.

 

[bibilit]

Some are availlable around, including among the folks here at 68Kmla, but is quite expensive if you can find one.

Also, is working with cartridge type "ROM Packs" and you should have the one suitable for your computer.

You will find information here:

http://www.forcedperfect.net/hardware/other/techstep/

Never seen one for real by the way.

 

[Sinclair]

With the disk image that indicated above would suffice.

 

[Sinclair]

This work has served to rule out a failure of VRAM:

I guess the next step is to replace the video muxes F253, .. or am I losing my time and money?  

 

[techknight]

PALs PALs PALs.... 

I guess this context was lost in translation somewhere? 

 

[Sinclair]

In fact. As I told the translator translates, "FRIENDs, FRIENDs, FRIENDs"
 
If I'm not mistaken there are at least 5 custom chips ...
Would you be so kind as to be a little more specific?

 

[CC_333]

P.A.L. = Programmable Array Logic. Your translater shouldn't have any trouble with this!

c

 

[Sinclair]

Hahaha, of course, my translator and I know the meaning. I was just kidding
 
Thank you anyway.

 

[CC_333]

Of course. We're all friends here! :lol:

By the way: I meant translator. Not translater.

c

 

[uniserver]

after all its not like TK knows what he is takin bout or nothin  haha

 

[Sinclair]

I do not understand his slang phrase, but I guess the meaning.
Translators still have their limitations.
 
I Only try to exhaust all possibilities before having to pull my PCB because I can't no replace some components that are impossible to get.
 
This to You seem to have it easy and should also be the solution for you. 
On the other hand I should clinging to any possibility. 
Not know if you understand this.
 
So the next thing I will do is replace the video muxes and we will see what happens. The hope is the only thing to be not missed.