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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: alexandrohipolito on September 06, 2010, 08:47:34 PM

Title: black key on A600 back
Post by: alexandrohipolito on September 06, 2010, 08:47:34 PM

What is the function to black switch on the to the a600? next to RF connector

Title: Re: black key on A600 back
Post by: Tenacious on September 06, 2010, 09:00:34 PM

Quote from: alexandrohipolito;578096

What is the function to black switch on the to the a600? next to RF connector

I think the 600 is the only Amiga with a built-in radio frequency modulator (the video can be sent to the tuner of an old-style television).  I believe the switch selects channel 2 or 3 to send the signal through.  Try it out if you have one.

Title: Re: black key on A600 back
Post by: meega on September 06, 2010, 10:33:34 PM

A1200 has a built-in modulator too.

In the US I think you are right, it changes the channel (frequency). In a UK/PAL machine I believe it selects low or high level output (there is a small screw to adjust the output frequency).

Title: Re: black key on A600 back
Post by: Amiga_Nut on September 06, 2010, 11:33:54 PM

Most Commodores had the switch too and so does the external, selects 5.5 or 6mhz sound frequency for the TV IIRC.

Title: Re: black key on A600 back
Post by: alexh on September 08, 2010, 10:52:18 AM

Yup, you're right. The H/L switch on PAL modulators adjusts the Audio subcarrier frequency.

PAL regions have different audio sub carrier frequency depending on which region.

H = 6MHz (UK, PAL-I)
L = 5.5MHz (Europe, PAL B/G)

Or maybe it's the other way around?

Anyhow it is the screw which adjusts the video UHF frequency on PAL modulators.