RF shield and picture

[Protek]

My A500 is currently missing its upper RF shielding and when it's on, there is a wide shadowy section on the display scrolling slowly upwards. The shadow is quite sharp contrast to the default grey background color of WB2.11. How much if at all does the absence of the RF shielding affect this effect? I've got an LCD TV and the A500 is connected via RGB cable. My A1200 doesn't have the same effect using the same cable and display even though it is also missing its upper RF shield.

[_ThEcRoW]

I have all of my amigas without the rf shielding, and never had any problem with it. The a500 and a1200 ones that still are in his original cases, are without the shielding and work perfect. There is maybe another thing thats is producing that weird behaviour. Since you are using an a500, the problem maybe its on the a520 modulator. Does the shadow still applies when using the monochrome output of the 500?.

[Protek]

Sorry, don't have an A520. :-) Using RGB cable. I can give the monochrome a shot. Can this be something Denise related?

[rkauer]

 The RGB cable is the more probable culprit.

 Substitute it for a shielded cable.

[Protek]

rkauer wrote:
 The RGB cable is the more probable culprit.

 Substitute it for a shielded cable.

I could give that a try since I have another that I've made out of shielded Scart cable. That's considerably shorter too.

[sim085]

Hi, I am not talking about the tip shield over the motherboard but the shield on the back of the A500+. Without that one I have the same problem as you. Similar to you I have do not use the A520 but some (custom made by my cousin) RGB converter. Without it my picture on the screen is very black, with it everything is normal.

Hope this helps
Regards,
Sim085

[Protek]

sim085 wrote:
Hi, I am not talking about the tip shield over the motherboard but the shield on the back of the A500+. Without that one I have the same problem as you. Similar to you I have do not use the A520 but some (custom made by my cousin) RGB converter. Without it my picture on the screen is very black, with it everything is normal.

Is that shield external? Do you have any pictures?

[sim085]

I do not have a picture but I can try and explain better

As much as I know there are two (2) metal shields. There is the most obvious one which sits on top of the motherboard and there another one which is between the motherboard and the back of plastic case. It is this second metal shield which without it I had this weird affect. My cousin told me it could be because of interference generated by the motherboard. That metal shield stops those type of interference from reaching that RGB converter. This metal shield obviously came out of the box with my A500+.

Regards,
Sim085

[Protek]

Ok, so it's the bottom half of the RF shielding, on which the mobo rests. Yeah, I've got that still in place.