AMIGA 1200 Video problem. Please help!! :)

[sir_bacharach]

Hi,
I have just bought Amiga 1200 with the following issues.

When RGB to SCART cable is used the image has a slight red hue.

When Composite is used the image has a strong yellow hue and is torn and moving (not useable).

When RF is used the image is similar to composite but the TV doesnt like the weakness of the image so flicks on and off.

I'm guessing the RGB is the signal at its rawest. So perhaps something between that and the encoder since the composite and RF are both poor.

Another thing is that I have removed the motherboard and found that someone had done some work on the modulator as the solder didn't look perfect. But could a dodgy RF modulator cause the other two outputs to be effected since the modulator is meant to be the last in line to output video?

Are there any caps or resistors you can suggest looking at?

I'm going to test the RGB to Scart cable on a working Amiga to see if the red hue is caused by a component in the cable as the RGB red hue may be coming from that rather than the actual RGB output itself.

I have a multimeter at hand and a soldering iron. I'm ready to go!!

Fingers crossed one or more of this fantastic community can help?

[amiman99]

It's been mentioned before, most A1200s have leaked CAPACITOR issues, so replacement should be done. Check for bulging tops on CAPS or liquid/residue around them.

Check if you have sound problems also, if you do, such as cracking, missing, low sound, then then it is confirmed that the caps have leaked and need to be replaced.

[sir_bacharach]

The caps are tiny little square nobbies on these boards arent they? Im used to caps being large cylindri al things. .

[amiman99]

Not that tiny, see this page: http://www.panasonic.com/industrial/images/electronic-components/4.1-capacitive-products/EEE-FT.jpg

[sir_bacharach]

Thanks, I think I will take a look at replacing these, I think I'll practice my soldering on some old useless PC parts until I feel confident.
 
I'm worried it might be the Video DAC. :S
 
Rob.

[paul1981]

Thanks, I think I will take a look at replacing these, I think I'll practice my soldering on some old useless PC parts until I feel confident.
 
I'm worried it might be the Video DAC. :S
 
Rob.

Amigakit sell A600 and A1200 Capacitor Packs:

http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=1137

I think there's a 50/50 chance it is indeed the caps causing your problem. I had an A600 that kept flickering into B&W and weird colours and that was a caps issue, so yeah, I'd get them changed. If it fixes the problem then it's one more Amiga saved from landfill or (shock horror) incineration. :cry:

[amiman99]

Verify the MB to see if the previous owner did not damaged it, before attempting any repairs.

[sir_bacharach]

Thanks paul. I will give it a go. It's worth a try. I suppose spending thr monrh is worth the experience of frying to fix it.

And thanks amiman. The previous work doesnt look to have damaged the mobo. Will see what I can do and will post my findings.

[mrknight]

Check out RetroGameModzs channel on YouTube:
http://www.youtube.com/user/RetroGameModz

He recently commented on a video where seomeone has a red tinted video output. It might be worth keeping an eye on that video.

Could it be your video?