video but no sound on my colecovision

[metzger130]

I have a Colecovision and I get a good picture but the sound is nothing but fuzz or static type sound. I was wondering if I open it and clean it out if that will fix the sound or if it needs something more done to it. I tried to attach a video, but evidently I'm not allowed to on here. Hopefuly the description will be enough to get some help.

Thanks!

Rob

[NIAD]

Send Yurkie a PM as he does repairs as well as mods on the ColecoVision. His work is TOP NOTCH and we are lucky to have him in the community!

 

As far as your system, I doubt cleaning it will remedy this sound issue, which is probably either the sound chip or maybe the RF board, but it a good first step. BTW, have you tried a different RF cable? Don't ruin the front bezel label to get to the screws underneath in order to open the system as there is a better way that is detailed in the PINNED thread on the main CV&ADAM Forum page.

[metzger130]

I didn't think it would be the RF cable as it was hooked up to my 7800 and I also got a Intellivision at the same time and it plays perfectly.

[SiLic0ne t0aD]

Could be a bad RF module on the board, thats my guess.. Hard to tell without actually looking at it.

I'd get yurkie's A/V mod board and install that, see if it helps. Thats a must have mod for newer TV's and improves everything in general.

Definitely contact Yurkie on this one.

[metzger130]

How would the AV mod make the screen look good and actually get sound out of the system? If something is wrong with the audio chip, why would it make sound with the a/v mod?

[thecrypticodor]

Could be the Audio is out of alignment with the video there are two potentiometers in the modulator that your can try adjusting.

o

 

The CV is one of the easiest consoles to composite mod so you can do it your self for almost nothing following this schematic. Or you can test the audio spot mention in the schematic to verify whether or not the chip is at fault.

Edited February 25, 2014 by thecrypticodor

[Beatnik]

Could be the Audio is out of alignment with the video there are two potentiometers in the modulator that your can try adjusting.

 

 

Wish I had found this before I replaced my chip. Audio alignment is all I needed.

 

Thanks !

[bikeguychicago]

Could be the Audio is out of alignment with the video there are two potentiometers in the modulator that your can try adjusting.

o

 

The CV is one of the easiest consoles to composite mod so you can do it your self for almost nothing following this schematic. Or you can test the audio spot mention in the schematic to verify whether or not the chip is at fault.

Colecovision av mod.png

 

I was having the same video but no sound issue. After adjusting the pot, it works fine now.

 

It's great having a resource one can turn to for troubleshooting something this old (especially for those of us who didn't have on in the day).

[spellingmisteaks]

So yeah, there are two adjustment screws in the RF modulator: The one closer to the RF jack adjusts the audio channel frequency with respect to the video. Turn that one until you hear the audio loud & clear. The other screw acts as a sort of fine tuning. If there's static on the screen, turn this one until the picture clears up.

 

It's worth noting that they're not potentiometers, they're threaded ferrous slugs inside of coil inductors. You'll want to use a nylon adjusting tool to tweak these, because a metal-tipped screwdriver will affect the inductance, and make it harder to get them properly dialed in. They're also fragile and can crack easily, so be gentle.