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#1
11-02-2006, 10:15 AM
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Question on buzzing sound at low volume...
Hi, quick question for the AK braintrust:
On one of my tube sets, if the volume is turned all the way down or is set low, I can hear a buzzing sound. It can be worse with white lettering on the screen. If the video is off-tuned to distortion, but the audio signal is still tuned in (ie on a UHF station), the buzz goes away. It seems worse with more white on the screen, but not that much worse. Is this situation adjustable with the AGC control? Thanks! 
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#2
11-02-2006, 11:56 AM
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If this is a Zenith there is a control on the back labeled "buzz" which can be tweaked. I don't think RCA ever had such a thing. There is no harm in tweaking the AGC.
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Bryan
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#3
11-02-2006, 12:10 PM
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Hi Bryan,
It's the Sylvania you see here (1967).....pretty unoffensive, but wondered if it could be easily fixed....(I already adjusted the vertical height a bit since the photo was taken). So just turn the volume all the way down and turn the AGC knob to see if has an effect in lessening the buzzing sound, simple as that, no warnings or guidance needed? (I'll also look to see if it has a "buzz" knob). thanks
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#4
11-02-2006, 02:27 PM
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YOu need to perform a sound alignment on the set. see your service manual or sams. This is a common problem with old sets on a modern signal. Before you do that you can try sticking an attenuator before the antenna input.
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Jordan
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#5
11-02-2006, 06:33 PM
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Hi Jordan,
You're right--I just tweaked the AGC and found it does lower the buzzing sound, but at the cost of a bright, crisp picture. I ended up adjusting it a little and probably lost a little of the buzz with no picture quality loss. No skills in the alignment area....did drop the power on the signal amp though and found no difference--could this substitute for putting an attenuator inline? Just glad I didn't break the thing....these old sets are quite temperamental. thanks
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#6
11-02-2006, 07:24 PM
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If dropping the signal amp power still does nothing, buying an attenuator wouldn't help much either. If the set is still wearing its original electrolytics, I would start in the sound section. However, more than likely even if you do change out the caps, the sound stages will need to be aligned ayways. If you have a sams folder for this set, it will have detailed instructions on how to properly align the sound sections.
__________________
Jordan
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#7
11-03-2006, 09:12 AM
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Update:
After I adjusted the AGC a little and found some improvement in the sound, I shut the set off. When I turned it on later, it seemed even more improved. I had tinkered around with a few switches in the back such as CRT bias and something I can't remember but the settings were "soft" and "normal". I returned them to their original settigs, as they didn't seem to do much but add brightness I didn't need. No folders on the set. I was happy to get some improvement at all. It's sailing along pretty well now. Thanks for the advice.
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