CX4000 busted? [SOLVED]

Splashman · 16:55, 03 November 18

Hello everyone,
I have recently received a CX4000, which was guaranteed by seller to be in working condition, but I can't get it to run no matter what.

I'm using a 12V 1.5A center plug supply, common scart cable to Sony BVM with sync switch and Burning Rubber cart.
All I get is a flickering picture and no sound/buzz. The best result I can get is by activating H/V delay, showing only a grey screen with a black/orange bar.

Before I declare the thing dead and busted, I'd like to know what I can do for troubleshooting. First of all, what's up with the syncing, and how come the software doesn't run?
I do own a C4CPC if that helps.

gerald · 18:01, 03 November 18

Some basic test before using the C4CPC

Did you use a 9V supply input (the one close to the scart plug) or the 5V ?If you used the 9V, make sure you used the right power plug, then check that the 5V regulator is working. You will need a multimeter for this.
You can check it by opening the GX and test it on the power switch. The being 5V regulator before the power switch you can check it without switch the GX ON. If you have more than 5.25V there or less than 4.75V, than the regulator may be faulty and this may damage the C4CPC.

If the 5V is OK, just grab the ramtest.cpr in this thread (1st post) and put it in one free slot of the C4CPC, then start on this slot.
http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/quick-and-dirty-ram-test-for-cpcIt will give you a basic idea of the GX state.If it starts and you have a visible border/screen then it may only be a RAM issue. The test will report it.
If you have nothing, then the either the Z80 or the ASIC is dead. In the case of the ASIC, then there is nothing to do except getting a new GX4000.

Splashman · 19:28, 03 November 18

Alright, the voltage regulator seems okay (I hope?)

After trying the ramtest, I finally got to see a proper composite picture (though it's still very wobbly on RGB).

Blue frame and all red bars. Fixable?

gerald · 19:51, 03 November 18

Quote from: Splashman on 19:28, 03 November 18
Alright, the voltage regulator seems okay (I hope?)

After trying the ramtest, I finally got to see a proper composite picture (though it's still very wobbly on RGB).

Blue frame and all red bars. Fixable?

Fixable ? Yes !

You need to replace the 2 RAM devices (KM41464AP-12 or equivalent)
See the picture on the http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/(please-read)-gx4000-with-original-power-brick-and-c4cpc post