Weird colour problem

[Flonky_Tash]

Hello!

It's been a while since I've posted on here, but i'm back!

My CPC 6128 has just started being strange. There seems to be an issue with the colour. For example, on the basic screen, the yellow text is now displaying a as pale blue.

This has only just started happening, which was when I noticed the colours were incorrect all of a sudden during a game of The Addams Family.

Not sure what more I can add to this description of the problem, any help and advice will be very much appreciated.

Thanks!!

[gerald]

My CPC 6128 has just started being strange. There seems to be an issue with the colour. For example, on the basic screen, the yellow text is now displaying a as pale blue.

You're missing the RED component.
First check your video cable.
Then issue may be on the CPC (gate array), or the monitor.

[TFM]

Sounds like one of the R, G or B wires has no contact. Try to clean plugs.    Else measure if signals go through the cable. 

[Flonky_Tash]

Thank you very much such quick responses!

As far as I'm aware, it's not an issue with the monitor or cable, as I use it with an MP-3 with another popular UK 8-bit machine (don't judge me) and the colours are fine.

So I am thinking the issue is most likely in the CPC itself. How would I go about checking the gate array if that's possible?

[TFM]

Maybe it's one of the solder spots on the PCB, maybe broken or 'cold'. IMHO it's not the GA else you would probably see more severe effects.

Well, at least you know that everything CRT is ok, so open the CPC and take a look at the PCB.

Also check if colors like Red, Green, Blue are 'invisible' when using commands like:

INK 1,2 (Blue)
INK 1,9 (war that Green?)
INK 1,6 (Red)

Maybe that helps to locate the missing signal.

[ZbyniuR]

If yellow look like pale blue, it's not look like missing signal.

Yellow without green look red, or without red look green. So that have to be something else. Maybe cables on pins are in wrong order, or some of them are  connected with each other.

Check
BORDER 18   - schould be juicy green
BORDER 6 -   red
and BORDER 2 -  blue

And let us know effect.

[Bryce]

Thank you very much such quick responses!

As far as I'm aware, it's not an issue with the monitor or cable, as I use it with an MP-3 with another popular UK 8-bit machine (don't judge me) and the colours are fine.

So I am thinking the issue is most likely in the CPC itself. How would I go about checking the gate array if that's possible?

It's most likely just a bad connection on the monitor port of your CPC. Clean the contacts. I've never seen a gate array cause a problem like this, the GA either works completely or it dies completely.

Bryce.

[Flonky_Tash]

Thank you for your suggestions guys
Once I get home from work later I will check everything and try and give those connections a good clean. Strange that the colours just suddenly went. Doesn't seem to be any loose/broken connections that's for sure. No cold solders either as I haven't taken a soldering iron near the machine.

What would be the best way to clean the contacts on the monitor port? Being ever so careful not to damage anything or make things worse!

[Bryce]

Use any contact cleaner or isopropanol to clean the contacts.

What has "I haven't taken a soldering iron near the machine" got to do with it having cold joints or not? It could still have cold solder joints even if you'd never opened the case.

Bryce.

[Flonky_Tash]

Ahh okay then, sorry I guess I don't know too much about soldering 

I will let you know how it goes later!

Thanks!

[Bryce]

A cold joint or dry joint is when the solder joint becomes brittle and cracks or disconnects from the contacts it's meant to be connecting. It usually happens when the contacts haven't achieved a high enough temperature to bond to the solder or if the soldering temperature was too high. It can happen with both hand soldering and industrial scale soldering.
In DC signal circuits this can result in a complete disconnect, in AC signal circuits it can have the effect of a capacitor in series with the signal which can have all sorts of effects depending on what frequency the signal is. 

Bryce.

[Flonky_Tash]

Okay, I have tested the colours with the commands "BORDER 18, BORDER 6 and BORDER 2" and are fine and look normal as they should. But the text is still pale blue. I have also cleaned the contacts with ispropyl alcohol and still get no luck.

Any suggestions on where to go from here?

[EgoTrip]

Are you sure you're not using a Commodore 64?

[ZbyniuR]

Are you have original ROM or modify?

Try  CALL &BC02   or   INK 1,24   
If after this  PEN 1  still is pale blue, I give up.

[Flonky_Tash]

It has the original ROM. Nothing inside has been changed at all since I bought it a few years ago.

However, I have just won another CPC 6128 off ebay yesterday, which is working just fine So I am going to be using that for the time being.

I will get back to this colour problem another time. Thank you everyone for your suggestions It is very much appreciated!

[Flonky_Tash]

Well, I found out what the issue is. It is actually the gate array chip.


So as I mentioned previously, last week I got a new CPC 6128 from ebay. So, as an experiment, I took out the 40010 chip from the new machine and put it in the other one with the colour problem. Turned it on and now the colours work as they should! 


To confirm this, I placed the faulty chip in the new machine and yep, it's definitely the problem.


Thank you again for people's advice


I don't suppose anybody knows where I could possibly get a hold of a new 40010 chip?

[gerald]

I don't suppose anybody knows where I could possibly get a hold of a new 40010 chip?

On Cent Pour Cent - CPC News store 

[Flonky_Tash]

Wow, excellent!


Thank you very much Gerald! 

[Docent]

On Cent Pour Cent - CPC News store 

At €9,223,372,036,854,775,808.00 The FDC there is seriously overpriced

[TFM]

At €9,223,372,036,854,775,808.00 The FDC there is seriously overpriced

A bargain compared to the pieces on ebay. 

[EgoTrip]

At €9,223,372,036,854,775,808.00 The FDC there is seriously overpriced

Wow did hyper inflation kick in overnight?