Author Topic: RGB Mod on Core Grafix. Buzzing sound on 1084 monitor  (Read 214 times)

mamejay

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RGB Mod on Core Grafix. Buzzing sound on 1084 monitor
« on: June 02, 2011, 05:52:35 PM »
Hello Everyone,

Just wondering if someone can help.

I recently converted a Core Grafix console from a 5 pin din to a 8 pin din to allow for RGB output.
To amp the signal I just used basic set of transistors on each of the red, green, blue and Csync lines.
I only have a early 1084 monitor to test the RGB.
I created a scart lead for it.  The image quality is perfect.  I just get a buzzing sound VIA the audio.
If I use the standard 5 pin composite cable the audio is perfect.
What is causing this?  Is it something to do with my 1084 monitor and the audio inputs VIA the SCART connector?
I have created a new cable and triple checked the connections and everything is perfect.
Any advice?
Thanks

mamejay

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Re: RGB Mod on Core Grafix. Buzzing sound on 1084 monitor
« Reply #1 on: June 03, 2011, 12:00:55 AM »
More information now.
I have done more testing and it looks like if Csync is connected its the right channel audio that gets effected with the buzz.
This also happens when using the standard composite lead.
If i use composite video for the sync signal I get perfect audio but the picture is terrible.

Anyone?

mamejay

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Re: RGB Mod on Core Grafix. Buzzing sound on 1084 monitor
« Reply #2 on: June 03, 2011, 01:51:52 AM »
Strike everything.  I worked it out!!
My 8pin DIN I used had a bent pin that was bridging the right channel with the Csync.
All sorted now and working perfectly