Spectrum 128K (toast Rack) displaying white as yellow issue
Hi,
I have a chance to buy a Spectrum 128 (toast rack) model which the owner says is working fine except that when it is hooked up to a Amstrad Monitor that comes with it displays white as yellow.
Is it likely to be a problem with the monitor or the Spectrums rgb output?
He also says that as he doesn't own a CRT TV anymore he can't test it on RF! :-o
Regards
I have a chance to buy a Spectrum 128 (toast rack) model which the owner says is working fine except that when it is hooked up to a Amstrad Monitor that comes with it displays white as yellow.
Is it likely to be a problem with the monitor or the Spectrums rgb output?
He also says that as he doesn't own a CRT TV anymore he can't test it on RF! :-o
Regards
Post edited by AceGrace on
Comments
This is a claim I see often on ebay and other sites which I do not understand as both my flat screens will tune in speccy. Not brilliant piccies but good enough for testing.
Sorry no use answer for your actual question!
I'm guessing it could be a problem with the blue colour channel either at your monitor or your ZX. Hard to be sure without putting the hands on them, but I'm taking it from there and telling what I'd do.
First, connect the Speccy to the monitor with another RGB cable with exact pin out. I don't know if the Spectrum and the monitor are pin-compatible, problem could be this. If you don't have a spare cable, skip this.
Second, connect your Speccy to a regular TV and see how the image comes out. There are two ways you can do that.
1. You may want to try to tune it in to UHF channel 36 first and though the picture won't be great, it'll be useful enough to see if the colours are fine.
2. For a better picture and therefore a more positive conclusion, connect it to the composite video input of your TV as follows: RGB connector PIN 1 is signal, pin 2 is ground. Google for images of "zx spectrum rgb pin out".
3. Whatever the choice you make on how to connect it to the TV, press the BREAK key and reset the Spectrum. A test screen will show text and colour patterns. Google for this image for reference too.
If the colours are fine, your ZX is ok, the fault might be:
1. your RGB cable. replace it and give it a try.
2. your monitor blue channel, perhaps something as simple as the connector or internal contacts. Perhaps not.
If the colours aren't ok, then you have an unfortunate fault at your Spectrum, which appears to be with the BLUE colour as green+red gives you yellow, but it would be white if there was blue to add to them. The fault, again, can be something as simple as the connector.
The blue colour in the RGB connector is pin 8, it's located exactly at the center of the connector. Clean and check it.
In case cleaning it wouldn't solve the problem, follow the track from pin 8 inside the Spectrum. Take an overview and see if you have anything suspicious. Measure the diode at the pin 8 output.
Next step would be checking the rest of the video circuitry around the TEA2000. That would make this message way longer. I think you have food for thought for now. Hope this can help and anyone more experienced can add to it or fully discredit it with better explanations as I want to know more.
Regards
Likely as not, the tube is on the way out and the blue gun has gone dodgy.
Looks like the colour problem definitely is the monitor.