| [GMCnet] radio noise [message #337779] |
Thu, 11 October 2018 08:02  |
Dean Hanson
Messages: 114
Registered: May 2018
Karma: 2
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Bill;
I was having problems getting my rear battery to charge in the Avion and
thought I would have to run another isolated wire direct. Further
investigation found a 30 amp fuse that looked good was really burned out.
There is no noise from my converter but with the coached on shore power and
the new fuse plugged in, the rear speakers (with the radio off) both hum
like the sound of a battery charger. That drove me nuts until I found the
source. Something is in those speakers to make that happen.
Dean C. Hanson 75 Avion
Fremont, Ca. 94536
(510) 657-9600
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| Re: [GMCnet] radio noise [message #337786 is a reply to message #337779] |
Thu, 11 October 2018 10:06  |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Not in the speakers, in the amplifier connected to them. What you are hearing is the reverse leakage current through the transistor amplifier that powers those grounded speakers. Indicates a wave of AC current on the charge circuit or weak reverse voltage characteristics of the amplifier.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] radio noise [message #337790 is a reply to message #337786] |
Thu, 11 October 2018 13:27 |
NextGenGMC
Messages: 146
Registered: December 2017
Location: Washington State
Karma: -1
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Senior Member |
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I'm getting the same noise in all of my speakers. PO connected the stereo system to "Hot at all times" wire on the engine battery. Several times in the past my engine battery got drained completely (had to start using the booster battery circuit). I think the battery drain is related to the static noise in the speakers. For now, I just disconnected all of them and made a note in the "Fix this when you have time" list.
What is the best way to deal with this issue? Does it indicate a bad amplifier or the stereo system that needs to be replaced?
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
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| Re: [GMCnet] radio noise [message #337797 is a reply to message #337795] |
Thu, 11 October 2018 16:01 |
NextGenGMC
Messages: 146
Registered: December 2017
Location: Washington State
Karma: -1
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Senior Member |
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Do you know what is "acceptable" current bleed on a "typical" CD/Radio unit? My guess if it bleeds due to internal circuitry malfunction it will be above nominal stand-by amp flow.
Vadim Jitkov
'76 Glenbrook 26'
Pullman, WA
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| Re: [GMCnet] radio noise [message #337802 is a reply to message #337797] |
Thu, 11 October 2018 20:04 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Standby current needs to be less than 10 ma for a month long storage with enough power left over to start the engine. 20 ma will shorten that time to a week. YMMV, and weak batteries need not apply. Simple radios/cd players, etc. should be about 4 ma or less by themselves.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] radio noise [message #337817 is a reply to message #337802] |
Fri, 12 October 2018 17:22 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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In the current MFJ catalog, on page 32 are several choices for RFI suppression chokes. Looking at ham radio stuff again. They have a web site. Put 'rfi' in search block. Many different options, cheap enough to try. Any interest, I came bring some to International Rally in Florida.
Tom
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] radio noise [message #337838 is a reply to message #337817] |
Sat, 13 October 2018 16:34 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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Check Amazon also. RF chokes are there, as well as RFI suppression.
Tom
2012 Phoenix Cruiser model 2552
KA4CSG
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