Capacitor couple your audio out

[boardjunkie]

I was testing a CV I repaired tonite and noticed when I plugged the audio cable in with the console already on, I got a "pop" in the sound. It sounded to me like DC on the audio output, and sure enough my meter showed around 5vdc there. I looked up the datasheet for the sound generator chip and it *does* need to be cap coupled to remove the DC voltage. A 10u 16v part should be plenty good enough. You can go bigger, the value isn't critical. Negative side goes to the audio out connector (pos side to the chip).

 

Just FYI.....

[Ikrananka]

I was testing a CV I repaired tonite and noticed when I plugged the audio cable in with the console already on, I got a "pop" in the sound. It sounded to me like DC on the audio output, and sure enough my meter showed around 5vdc there. I looked up the datasheet for the sound generator chip and it *does* need to be cap coupled to remove the DC voltage. A 10u 16v part should be plenty good enough. You can go bigger, the value isn't critical. Negative side goes to the audio out connector (pos side to the chip).

 

Just FYI.....

What is the downside of NOT having this capacitor, apart from the pop when connecting audio when the CV is turned on? Was this probably omitted by Coleco as a cost saving measure?

[boardjunkie]

I was testing a CV I repaired tonite and noticed when I plugged the audio cable in with the console already on, I got a "pop" in the sound. It sounded to me like DC on the audio output, and sure enough my meter showed around 5vdc there. I looked up the datasheet for the sound generator chip and it *does* need to be cap coupled to remove the DC voltage. A 10u 16v part should be plenty good enough. You can go bigger, the value isn't critical. Negative side goes to the audio out connector (pos side to the chip).

 

Just FYI.....

What is the downside of NOT having this capacitor, apart from the pop when connecting audio when the CV is turned on? Was this probably omitted by Coleco as a cost saving measure?

 

 

This applies to the seperate video/audio output mods only. The audio to the RF box is cap coupled. But the popular internet modders don't know to cap couple the audio for the line level output, they're just running cable straight to the output connector, which is the wrong way to go about it. It states right in the datasheet for the sound generator chip that the output *needs* to be cap coupled.

 

If you don't do this, you have 5vdc on the audio out all the time and your TV/stereo does not want that, it just wants the audio signal. So depending on the input design of whatever you route the audio to, you may risk damage leaving it direct coupled. A higher end stereo amplifier may be direct coupled from front to back, and DC voltage on an input will cause it to go into protect mode thinking there is a problem with the output section. If it is not protected, you'll have a DC voltage on your speakers which *will* damage them. I'm really surprised no one has caught this before. Its pretty important.....