Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: shooey on March 27, 2013, 11:44:40 AM
-
Hi,
I have an Amiga 500 which I haven't used in a long time, and have been trying to get it working. It boots up fine, but the problem is, I can hardly see the display.
I've tried connecting the RF output into an aeriel socket and tuning in on analogue, and I've tried the video output into a scart socket (capable of RGB) using a fully wired scart adapter, and I've tried the video output into the yellow socket of 3 phono plug connection. I've actually tried all those things on 2 different TV's.
In all cases the picture looked like it wasn't tuned in properly, and on one of the TV's it was rolling.
I've seen in other posts, that rolling can be a sign of NTSC, but I can think of no reason why it would be NTSC as it's an English Amiga and I'd never fiddled about with the settings that I can remember.
Can anyone suggest anything that I can try, or is it likely that the TV modulator no longer works properly?
*apologies for all the incorrect terminology used above, but you can hopefully figure out what I mean*
Thanks
-
Hi,
I have an Amiga 500 which I haven't used in a long time, and have been trying to get it working. It boots up fine, but the problem is, I can hardly see the display.
I've tried connecting the RF output into an aeriel socket and tuning in on analogue, and I've tried the video output into a scart socket (capable of RGB) using a fully wired scart adapter, and I've tried the video output into the yellow socket of 3 phono plug connection. I've actually tried all those things on 2 different TV's.
In all cases the picture looked like it wasn't tuned in properly, and on one of the TV's it was rolling.
I've seen in other posts, that rolling can be a sign of NTSC, but I can think of no reason why it would be NTSC as it's an English Amiga and I'd never fiddled about with the settings that I can remember.
Can anyone suggest anything that I can try, or is it likely that the TV modulator no longer works properly?
*apologies for all the incorrect terminology used above, but you can hopefully figure out what I mean*
Thanks
If you've tried 2 different TVs and you've done RF, composite mono (the yellow phono connector on the left side at the back), and RGB via scart and they all look fuzzy it sounds like you've got a fault.
First thing to check is the Power Supply, then I guess its time to open the Amiga up and look to see if you can see any damage. It could be a capacitor problem but my first thought is the power supply.
EDIT: Also note, if this is a 500+ there will be a leaked battery inside that needs removing and cleaning up and will have damaged the board. If you have a memory expansion in the trapdoor that could also have a leaked battery which may or may not have damaged the expansion and or the motherboard - try removing expansion and retest if there is one.
EDIT2: You mentioned you've tried RGB - do you mean you've got an amiga to scart lead which plugs directly into the port where the modulator normally goes? You've tried that as well and get a fuzzy picture? Post a photo of the screen if you can so we can see what the fuzziness looks like.
-
You need to clarify what you mean when you say you used RF. Amiga 500s do NOT have an RF output as default. You only get that when you have an A520 connected to the RGB port.
Is that what you meant?
-
You need to clarify what you mean when you say you used RF. Amiga 500s do NOT have an RF output as default. You only get that when you have an A520 connected to the RGB port.
Is that what you meant?
Sorry - when I said 'TV modulator' I meant A520 - I didn't know that's what they were called.
So yes, I have an A520 connected, and have tried the RF and video outputs of the A520.
Anyway, thanks for both replies. GadgetUK suggested a few things to try, so I will do that, and also post some pictures so you can see what the fuzziness looks like.
Thanks
-
So, did you try the monochrome video output on the actual A500 itself into the video input of your monitor/TV?
It's the little, lone RCA jack beside the RGB video port.
If that works then your A520 may be faulty.
-
Hi,
I did have an memory expansion in under the one of the flaps underneath and have tried removing that, but it's made no difference. Here are a few pictures...
Thanks
-
Remove the A520 and try the A500's monochrome video output connector.
-
So, did you try the monochrome video output on the actual A500 itself into the video input of your monitor/TV?
It's the little, lone RCA jack beside the RGB video port.
If that works then your A520 may be faulty.
Hi,
No - haven't tried that. Didn't even know you could - I thought 'mono' was referring to audio! Will give that a go...
Thanks
-
Please let us know how it goes....you can't leave us hanging! ;-)
-
Hi,
Absolutely perfect picture via mono socket. So I guess my A520 is faulty. Thanks very much for all the help.
Cheers
-
Hi,
Absolutely perfect picture via mono socket. So I guess my A520 is faulty. Thanks very much for all the help.
Cheers
Awesome! Dont throw that modulator away, either I can take a look at it for you, or stick it on EBAY as faulty.
-
Thanks Gadget. Will have a think what to do, but may get back to you on that...
-
Thanks Gadget. Will have a think what to do, but may get back to you on that...
There are a couple of potentiometers inside the A520 that may just be dirty. Mark their positions and try twisting them back and forth (with a small screwdriver) then return them to their original positions. If you have any contact cleaner spray it inside the potentiometers.
It might be that's all that is wrong with the A520.
You can probably find out what these potentiometers do on the internet somewhere.
-
Thanks. Will give it a go. Nothing to lose...
-
Hi,
Absolutely perfect picture via mono socket. So I guess my A520 is faulty. Thanks very much for all the help.
Cheers
Use SCART.
-
There are a couple of potentiometers inside the A520 that may just be dirty. Mark their positions and try twisting them back and forth (with a small screwdriver) then return them to their original positions. If you have any contact cleaner spray it inside the potentiometers.
It might be that's all that is wrong with the A520.
You can probably find out what these potentiometers do on the internet somewhere.
Hi ral-clan,
Wonder if you'd be kind enough to expand on your what you'd said above?
If we look at the photo here:
http://amiga.resource.cx/photos/a520,4
Which bits are we talking about? Within the metal square on the right hand side, the white thing in the middle looks like it has a screwdriver type hole in it. Or is it the two things either side of that?
Thanks
-
Hi ral-clan,
Wonder if you'd be kind enough to expand on your what you'd said above?
If we look at the photo here:
http://amiga.resource.cx/photos/a520,4
Which bits are we talking about? Within the metal square on the right hand side, the white thing in the middle looks like it has a screwdriver type hole in it. Or is it the two things either side of that?
There are actually four potentiometers in the metal box as shown in that picture. The white plastic thing, the two on either side, and one more roundish one to the south-east of the right potentiometer. They all have slots in the top that you can adjust with a fine screwdriver. You can do this while the Amiga is turned on, but you would normally use a plastic screwdriver. I have done this myself with a metal screwdriver wrapped in electrical tape around the handle. I don't think there are any voltages in there that are dangerous, just the chance of slipping with the metal screwdriver and shorting something on the board. Perhaps you can make yourself a sort of slot type screwdriver from an old plastic knife or chopstick or something if you don't want to risk using a metal screwdriver.
I'm not sure which "pots" do what function, but on other computers and video games they normally adjust the TV channel fine tuning for the RF output, the colour saturation, perhaps luminance and some other related stuff. You would mark their original positions with a fine felt tip marker, and then with the Amiga on and the A520 opened up but plugged into it, you would make gradual adjustments to the potentiometers to see what happens to the picture.
You can also spray contact cleaner into them if you are able, and then wiggle them back and forth with the screwdriver to clean out any oxidization. You'll need something like TV-tuner contact cleaner or other electrical contact cleaner spray that uses one of those fine red straws to focus the spray. This is actually something you could try first with the Amiga off to see if it fixes the problem.
Again, I don't know exactly what these particular potentiometers do, as I haven't seen a service manual, so take my advice with a grain of salt, but they are there to be adjusted by a service person or in the factory.