Frequency Hum/Buzz Over Radio
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Joined: Aug 2009
Posts: 65
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From: Rio Rancho NM
Frequency Hum/Buzz Over Radio
So on my '77 resto-mod I have the common annoying hum. I know there is a transistor in the system to compensate for this annoying hummmm/buzzzzz, but through my restoration process, I am now not sure if I replaced the transistor at all, and in fact in the correct place.
Can someone out there please help by telling me where that transistor was normally placed by GM.
I recall removing a transistor like cylinder from the engine manifold area near the distributor due to a broke wire and now I am wondering if that was what I removed. Currently, whenever I rev the engine the hum/buzz increases as well.
Thanking you all in advance.
Can someone out there please help by telling me where that transistor was normally placed by GM.
I recall removing a transistor like cylinder from the engine manifold area near the distributor due to a broke wire and now I am wondering if that was what I removed. Currently, whenever I rev the engine the hum/buzz increases as well.
Thanking you all in advance.
Racer
Joined: May 2014
Posts: 420
Likes: 5
From: Springfield Missouri
The object you removed from near the distributor may have been the tach filter.
As far as the buzz you hear... I understand these cars came with ignition shielding to prevent radio interference. If you are missing that I suppose it could be the source of your problem. I say 'could' because my 76 doesn't have the shielding and I have no discernible buzz in my radio.
As far as the buzz you hear... I understand these cars came with ignition shielding to prevent radio interference. If you are missing that I suppose it could be the source of your problem. I say 'could' because my 76 doesn't have the shielding and I have no discernible buzz in my radio.
Team Owner
Joined: Jul 2004
Posts: 40,368
Likes: 787
From: Redondo Beach, California
The object you removed from near the distributor may have been the tach filter.
As far as the buzz you hear... I understand these cars came with ignition shielding to prevent radio interference. If you are missing that I suppose it could be the source of your problem. I say 'could' because my 76 doesn't have the shielding and I have no discernible buzz in my radio.
As far as the buzz you hear... I understand these cars came with ignition shielding to prevent radio interference. If you are missing that I suppose it could be the source of your problem. I say 'could' because my 76 doesn't have the shielding and I have no discernible buzz in my radio.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
What you removed was a capacitor. Often referred to as a filter. what a capacitor does is pass ac ripple to ground without grounding the dc portion of the circuit.
That ac ripple is the buzz you are hearing.
Replace that filter and it may clear up your problem. Otherwise you could try a capacitor attached to the power supply for the radio and the other end attached to ground.
Electrolytic capacitors can filter as well but are positive/negative specific.
That ac ripple is the buzz you are hearing.
Replace that filter and it may clear up your problem. Otherwise you could try a capacitor attached to the power supply for the radio and the other end attached to ground.
Electrolytic capacitors can filter as well but are positive/negative specific.
