A500 Video Malfunction

[Sasuke]

HI.
I was using A500 with 520 modulator, and everything worked fine. One day while the Amiga was running with the TV on, the image suddenly disappeared and the Amiga power LED went out.
Approaching the Amiga, I distinctly felt the typical smell of burnt electronic components coming from the modulator.
I immediately unplugged and threw away the modulator, now surely gone.

Then I buy a rgb / scart cable on retrohax.
By connecting the cable to the LCD TV and turning on the Amiga, a white screen appears on the screen for a few seconds, the power LED of the Amiga flashes, then it stabilizes, resulting in a black screen......... and the sequence repeats itself in continuous cycle.


Trying to connect the cable with the Amiga already on, the image of the hand with the disk appears on the screen, but in continuous movement downwards. Subsequently, if I disconnect and reconnect the cable, the image appears to me always in continuous movement, but with the message
RECOVERABLE ALERT. Clicking the mouse repeats the problem.

it must be said that the scart cable bought on retrohax is the first time I use it. Could it have been built poorly?
Or probable Denise chip failure?

P.S. Without the scart cable inserted the Amiga starts correctly.

[simon_m74]

try a composite cable out - its black and white, but a good test

[Sasuke]

How is an Amiga composite cable made?
Does it always have to be connected to the RGB port of the Amiga?

[jurassicman]

the composite is a yellow plug that looks like the red and white for the audio. The cable is usually scart to composite, so you have a scart plug on a side and 3 (yellow, red and white) plugs on the other side.
The composite plug goes near the rgb socket on the back of the A600.
It should give you a color image (but with lower quality compared to the rgb).
The composite has black and white output on the A500, as far as I know, and color output on A600 and 1200.

Here an example:


This is where the yellow plug goes:

[Sasuke]

The A500 has no composite video output, only RGB.

Do you think the problem I described could depend on the scart cable?
Or is it some faulty component on the Amiga motherboard?

[Turrican_3]

Originally Posted by Sasuke

The A500 has no composite video output, only RGB.

As correctly stated by Jurassicman, composite (b/w) output is actually present on the back of the A500. Just have a look near the regular RGB connector.

[amigasith]

Originally Posted by Sasuke

Trying to connect the cable with the Amiga already on...

WHAAT Please NEVER EVER do this again!

There are so many reports by people who killed either custom chips or other ICs in their Amigas by plugging and unplugging the video cable while the Amiga is turned on that it is probably pure luck that you haven't destroyed anything - or perhaps you already have? Either way, it is by no means a good idea to plug and unplug the video cable when the Amiga is powered on!

[giantclam]

I immediately unplugged and threw away the modulator, now surely gone.

Should've kept the A520 modulator to determine failstate

[Sasuke]

Great Simon! A thousand thanks.
By carrying out the test you suggested, with the composite cable the image is stable, but black and white.

Jurassicman,
I apologize, I hadn't examined the back of the Amiga ports carefully.

Now what could be deduced from this test?

Could it be a defect related to the SCART/RGB cable?
Or is the fault to be found in the RGB port of the Amiga?