On a GX 4000 with NO MEMORY (Removed) does Geralds Ramtest Work ? ?( RESOLVED)

[Audronic]

Hi All


On a GX 4000 with NO MEMORY (Removed) does Geralds Ramtest Work ? ?


The machine has been through the wars.
Regulator DIED, Bridging Diode DIED
11 Volts on the 5 Volt Rail ?
The machine as I got it was drawing 3.5 Amps Hmmmmm..
Fixed the Regulator etc.
Removed the Z80 (Toaster) Repaced it and it went back to .3 amp a lot better.
The memory had been getting HOT before.
Snipped the Memory out and wondered " On a GX 4000 with NO MEMORY (Removed) does Geralds RamTest Work ? ? "


Any help would be appreciated.


Thanks.   Ray

[gerald]

Hi All


On a GX 4000 with NO MEMORY (Removed) does Geralds Ramtest Work ? ?


The machine has been through the wars.
Regulator DIED, Bridging Diode DIED
11 Volts on the 5 Volt Rail ?
The machine as I got it was drawing 3.5 Amps Hmmmmm..
Fixed the Regulator etc.
Removed the Z80 (Toaster) Repaced it and it went back to .3 amp a lot better.
The memory had been getting HOT before.
Snipped the Memory out and wondered " On a GX 4000 with NO MEMORY (Removed) does Geralds RamTest Work ? ? "


Any help would be appreciated.


Thanks.   Ray

Does it work ? Yes  But it will tell you that all the RAM is dead !

[Audronic]

@gerald


Ok Thanks.
I have not had anything on the screen, so I will have to assume that the MotherBoard is Terminal (no Pun intended)


Thanks.   Ray

[robcfg]

Well, what you see on screen is read from ram, so if you don't have any ram you won't be seeing anything, even if everything else works.

[Bryce]

Not quite right. The CPU tries to set up the CRTC even without any RAM present, so you should see something on the screen. If the screen is completely black, then something more (most likely the ASIC or DAC) has probably failed.

Bryce.

[robcfg]

That's interesting.


But besides a different border or background colour, what else could you see?


And if the default colours are black?

[Bryce]

I'm sure someone here has a CPC with socketed RAM. That someone could pull the RAM and tell us exactly what it produces. I think I recall it being a pink/purple mixture I got.

Bryce.

[CraigsBar]

* CraigsBar looks at @Shaun M. Neary I know the ram fix I did on his gx4000 used sockets.

[Bryce]

Unfortunately Shaun has left the Forum for now.

Bryce.

[GUNHED]

Great X-mass present, but in this case... maybe it's the best to trash it, because it looks like the ASIC is dead. Of course you can try to replace the RAM (with sockets of course to save the chips themselves). Wish you luck, but have doubts. 

[gerald]

@gerald


Ok Thanks.
I have not had anything on the screen, so I will have to assume that the MotherBoard is Terminal (no Pun intended)


Thanks.   Ray

Ramtest only test the RAM, but does not use it at all.
On a CPC without RAM you should see both the :
- in-progress screen : black  border, the screen should likely be red due to floating ram IO.
- the result screen  : blue border with raster indicating the individual bit status, screen should be cleared on working RAM (ie black). With faultily RAM you get garbage.
If you does not have the result screen 5sec, there is a problem somewhere else (supply too low, Z80, ASIC)

[Audronic]

Hi all who have contributed.


Thanks to Gerald for the definitive answer.
Thats exactly what I was after.


Thanks to Bryce for the recall about the Pink /Purple.


I think we can close this now.
Where is the AXE ( Or a non regulated 30 Amp Power supply) Oops where is the Fire Extinguisher.


Thanks all.     Ray