Author Topic: Oh No! My 464plus (with Internal Upgrades) has developed a fault.  (Read 5953 times)

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Offline gerald

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with internal 128 and xmem 512, artifacts.
They appear pretty constantly, but with most ferocity when testing row 7fc4
Artefact also on 7ec4 test ?
A video is welcome for the 128 internal + 512 external.
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Offline CraigsBar

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It would be better to keep them powered but have the CAS tight to 5V instead of beeing connected to the ASIC. If you remove the power and keep them in circuit, they may get damaged or perturbate the bus.


OK so if I follow this correctly. I have to switch pin 16 CAS on the IC between CAS on the Socket and +5 v


When It's connected to CAS on the socket it'll be 128k
When connected to +5v it'll be 64k


Is that right? and I Obviously have to do that for both of the 2nd bank IC's.


Craig

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Offline CraigsBar

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Artefact also on 7ec4 test ?
A video is welcome for the 128 internal + 512 external.


Ok 2 videos,


First up 128k all internal - no artifacts.
128k - YouTube


Then all 576k with xmem - artifacts.
576k - YouTube
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Offline gerald

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Then all 576k with xmem - artifacts.
576k - YouTube
It looks really different from Remax CPC sympthoms where artefacts are only interferences with the display scan. They disappear once there is no more access to the external RAM.
Here it looks like a real corruption of the video memory (and maybe other some location too). I only think about probing the RAM and the extension bus to understand the real problem.
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Offline CraigsBar

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It looks really different from Remax CPC sympthoms where artefacts are only interferences with the display scan. They disappear once there is no more access to the external RAM.
Here it looks like a real corruption of the video memory (and maybe other some location too). I only think about probing the RAM and the extension bus to understand the real problem.


Well Good news folks, the issue seems resolved!!


OK The only changes I have made are...


1. Cartridge swap (Parados cart swapped for c4cpc)
2. Replaced the fan in my ATX power supply, now it is not so loud I am using that for the xmem and HxC instead of 2 Iomega Zip Power bricks


and that is it. I guess the ATX Power supply provides a better, cleaner, more consistant 5v 2a than the Iomega brick did.


I set Symbos running through the Starfield screensaver for 2 hours tonight and not a single artifact was present. I have now run the full memtest dsk again, All blocks are green and lso no artifacts.


My 464plus is back and healthy with 128k and no problems. I am a Happy Chappy :)


Craig
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Offline Bryce

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Cool.

As mentioned before (in several other threads), using two PSUs in parallel is a really bad idea. Although the MX4 has a separate power socket, you should use a PSU powerful enough for everything and connect it to both the CPC and the MX4 input.

Bryce.
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