DDI1 Clone disaster

[eto]

Either inside the Zaxon DDI device

This particular device is really just a DDI1 clone and does not contain any RAM. 

Could it have been caused by the DDI1 clone?

I'm not an expert (let's wait for Bryce to confirm) but I would be surprised if the DDI could cause that. The internal RAMs are not directly connected to any lanes on the expansion bus.

But you should check the voltage that the CPC receives from the monitor if that's close to 5V or if it's maybe too high.

[angelcaio]

Either inside the Zaxon DDI device

This particular device is really just a DDI1 clone and does not contain any RAM.

Could it have been caused by the DDI1 clone?

I'm not an expert (let's wait for Bryce to confirm) but I would be surprised if the DDI could cause that. The internal RAMs are not directly connected to any lanes on the expansion bus.

But you should check the voltage that the CPC receives from the monitor if that's close to 5V or if it's maybe too high.

5.16V

[angelcaio]

Everything's going wrong!!!!
I took my M4 to load Gerald's test ROM onto it.
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/quick-and-dirty-ram-test-for-cpc
I powered on the M4 board via USB, without connecting it to the CPC. Using the web interface, I loaded RAMTEXT.ROM into ROM 0 and enabled the lower ROM. I connected it to my CPC-464 and booted it up.
all green appears on the screen, border and paper as same and now the M4 doesn't even respond to pings or access the web.
Even disconnected from the CPC and powered by USB.
Only the blue LED next to R6 remains lit.
When the USB is connected to power, the green LED next to R14 flashes briefly and then turns off.

[angelcaio]

Everything's going wrong!!!!
I took my M4 to load Gerald's test ROM onto it.
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/quick-and-dirty-ram-test-for-cpc
I powered on the M4 board via USB, without connecting it to the CPC. Using the web interface, I loaded RAMTEXT.ROM into ROM 0 and enabled the lower ROM. I connected it to my CPC-464 and booted it up.
all green appears on the screen, border and paper as same and now the M4 doesn't even respond to pings or access the web.
Even disconnected from the CPC and powered by USB.
Only the blue LED next to R6 remains lit.
When the USB is connected to power, the green LED next to R14 flashes briefly and then turns off.

I have deleted all files ion M4  directory of SD Card and the M4 board it works again. Phew, what a relief!
Any advice on how to properly load the diagnostic ROM?

[pelrun]

I loaded RAMTEXT.ROM into ROM 0

That "Lower-rom slot" field is the ROM slot you have to put the replacement lower-rom image into. So you should have put it into ROM 31, not ROM 0.

[angelcaio]

Lower-ROM enabled and the TEST ROM in slot 31, but it doesn't work until I press reset on the M4, while a screen appears with the paper and a dark green border.
My fault, I didn't notice this before. 

Now it shows this. It seems the faulty chip is the last one. Is this the most significant or the least significant?

The service manual mentions eight 64 Kbit chips, from IC117 to IC124.

I don't know which one I should change.

Any idea?

Note: The ROM that finally worked for me is this one:

https://amstrad.es/forum/viewtopic.php?p=87827#p87827

Thanks

[St-BeidE(DE/GB)]

...
The service manual mentions eight 64 Kbit chips, from IC117 to IC124.

I don't know which one I should change. ...

What brand is it?
In case its μT- Ram, i suggest you to change all at once. The question is not, if the RAM will fail,
but when it will.

Stefan 

[eto]

Note: The ROM that finally worked for me is this one:

Get the Amstrad Diagnostics Lower ROM: 
https://github.com/llopis/amstrad-diagnostics/releases/tag/v1.3

IC numbers are then documented here: 
https://github.com/llopis/amstrad-diagnostics/wiki

[angelcaio]

Thank you very much, I won't have access to 464 until next weekend.
I'll try this then