GX4000 Original Power Supply Brick

[Xyphoe]

So I am aware of course of Gerald's topic (https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/(please-read)-gx4000-with-original-power-brick-and-c4cpc/)

But whilst I'm finishing up a video to celebrate 30 years of the GX4000 this September, I've been looking into the GX4000 original power supply - and if it was dangerous.
There's been rumours for years that it can blow a GX so I want to 'myth bust' this or not.

Personally I used one for years in the late 90's / early 2000's not knowing about this apparent issue. I don't any more of course, why risk ANY old power supply!

So I've had someone respected and others who know their electronics look into them. The guy I trust (who runs a very popular computer electronics YouTube) in particular took one apart and couldn't find anything particularly bad in them - looks pretty standard - transformer, bridge rectifier and big capacitor - and a fuse (which the original Spectrum supplies never had!), and looks like if the cap dies it will as normal short to the ground and burn until the fuse blows... but shouldn't affect the GX4000. He thinks the only way damage could occur to a GX4000 is if something caused the current draw to increase blowing the voltage regulator and then RAM etc on the GX. When I told him about the C4CPC that will do that - well that is of course interesting and fits in with his theory. But we're not sure how a standard cart would do that...

Has anyone else looked into and confirmed the problems/issues with the original power supply? We know about the C4CPC, but that's a new thing.

Thanks!

[Bryce]

I've never understood the fuss about the original GX4000 PSU. It's a robust well designed PSU. The failure that gerald described could have been caused by a faulty PSU, but could have been caused by many other things. How many original PSUs were sold? And just one "suspected" failure? That's an incredibly good result.I would have no issues using the original PSU.

Bryce. 

[Xyphoe]

I've never understood the fuss about the original GX4000 PSU. It's a robust well designed PSU. The failure that gerald described could have been caused by a faulty PSU, but could have been caused by many other things. How many original PSUs were sold? And just one "suspected" failure? That's an incredibly good result.I would have no issues using the original PSU.

Yea similar thoughts to me, I used one for years, as I know a lot of friends did. First I heard of them potentially being bad I think was from Larry Bundy Jr on YouTube, then I watched Chinnyvision's video on the GX4000 last night and he says in it that he had 3 GX4000's blow up on him in the early 90's due to the power supply!
So I wanted to get to the bottom of this and if indeed they were dodgy.

[robcfg]

Wasn't it about the original PSU plus the C4CPC cartridge?

[Xyphoe]

Wasn't it about the original PSU plus the C4CPC cartridge?

Yes but it's been rumoured for years they were dodgy and can blow a GX4000, long before the C4CPC.

[gerald]

Basically, the original supply is fine. It use a standard design and there is no reason for it to burn a GX4000.
My thread mainly
- highlight one of the fault that can damage the GX4000, but I a still wondering the use can that will cause it (ie blowing the reverse diode on the 5V regulator)
- recommend a modern 9V supply for the increased consumption due the the C4CPC. The original supply is rated to 500mA, which is more or less what a C4CPC loaded GX4000 will consume.
- 9V to also reduce the heating of the 5V internal regulator. (2W to dissipate instead of 3W @11V and 3.5W @12V)

Now I do not have any idea how the original PSU could be held responsible for GX4000 failure. For that one would need to do  proper analysis of the failure, but I doubt anyone did that back in time.
Since the original PSU is barely stabilized, any over-voltage on the mail can potentially could cause an equivalent over-voltage on the secondary side. Is than enough to damage the GX400 ? Who knows 
But for sure, the 220V/11V original specification translates to 240/12V on today mains, one more reason to use a modern regulated supply to reduce the overheating. 

Also the fact that the power switch of the GX4000 is placed after the internal 5V regulator may play a role. The regulator is powered as soon as you plug the supply, the GX4000 being ON or OFF.