CTM 644 vs CRT TV

[ced64k]

To save space I'm thinking about keeping only my 2001 21" Philips CRT TV for retrogaming.



I was wondering about the image quality vs an Amstrad CTM 644. Is it worth it to buy a scart rgb cable and power supply ? What do you think ?

[||C|-|E||]

Well, the Philips is going to be probably better in terms of image quality. It happens that the CTM 644 is nothing special, mostly a cheap color TV with RGB input and no tuner. I like to repair, keep and use original Amstrad monitors, but it is for nostalgic reasons...

[roudoudou]

CTM644 does not have distortions like TV-CRT, especially like Philipps, Sharp and even Sony

[||C|-|E||]

CTM644s have purity problems, shadowing, are very sensitive to magnetic fields...  Distorsion is not heavy, although I have seen it too. Don´t get me wrong, I like them, but they are far from being really good displays. However, I must admit that they are quite robust 

[tjohnson]

I would have though it would be worth a try see what the picture quality is like and decide if you want to stick with the Philips.

[ced64k]

I received the din to scart cable today. I have strange black pixels moving on top of the screen. The cpc is powered with the CTM644, I'm waiting for external psu. This tv is working nicely with other RGB game consoles. Any idea ?

[Bryce]

How long is the cable? And have you cleaned the monitor socket pins lately?

Bryce.

[ced64k]

The cable is only one meter long.

I noticied there is no problem at beginning. After 1-2 minutes the blacks pixels appears and take more and more place on the screen.

Here's a video:


https://www.youtube.com/watch?v=3J3NXHWwYTs

[Bryce]

And you're 100% sure that other retro computers/consoles connected via SCART don't exhibit this? That looks to be a problem with the TV, not the cable.

Bryce.

[ced64k]

Yes, Megadrive RGB for example:

[Bryce]

Does the cable have any components in the SCART connector? How is it wired?

Bryce.

[ced64k]

Here it is

It's a cable from ikonsgr74 on eBay.

[mr_lou]

I would also say that a CRT TV generally gives a better picture than the CTM644. But not all.
I tried a lot of different TV's before finding one I was satisfied with, and it was a Philips.

[chinnyhill10]

CTM644 does not have distortions like TV-CRT, especially like Philipps, Sharp and even Sony

They do have distortions in line with cheap portables of the period. You don't tend to see the worst of it as these problems usually occur on the edges and the CPC has a border. Screening isn't great either so if a magnetic field gets anywhere near them you can end up with permanent distortion.


A CTM monitor is just a cheap TV tube in a custom box with RGB input. Nothing special. Even on the CPC's release the press noted that the colour monitor struggled in 80 column mode and that was just from seeing the machine at the launch!


Got an Acorn CRT here (rebadged Phillips) of roughly the same vintage (1989) as many CTM's. Whole different beast. Just better in every single way.

[ced64k]

Weird update:

I get a perfect image with this switch  between the tv and the cpc :



But only if the Megadrive is also plugged to the switch and... power on 


If I unplug the Medadrive the image become b/w, same effect as if I didn't push the RGB button on the switch.

It's stange because if I remember there is no electronics in this switch.

[Bryce]

Sounds like you have a floating ground. Can you solder?

We can try something out, but first check whether the brown wire is properly soldered at both ends.

Bryce.

[ced64k]

Can you solder?

I managed to solder a GPIO header on a Raspberry Pi Zero and against all expectations it works, so I will say yes