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#1
November 21st 04, 06:10 AM
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constant hum
Hi All,
My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick. 
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#2
November 21st 04, 06:29 AM
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unhook everything from the amp accept the speaker and whatever it uses
to power on , if it still hums it was not fixed right .
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#3
November 21st 04, 05:18 PM
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More than likely the caps in the power supply are not in the best of
condition. If you had a re-cap job performed on the amp the technician may have used old caps which were dry. Star by asking him if the eletrolytic caps were replaced. There are other options but this is the most obvious place to start. Jim "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick.
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#4
November 22nd 04, 01:02 AM
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Rick:
One of the overlooked problems is mechanical hum from fluorescent lamp ballasts and power transformers. Disconnect the speaker(s). If the hum does not go away, look at these items. If it does, then it is likely the main filter capacitors in the amplifier. -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick.
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#5
November 22nd 04, 01:29 AM
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You're not so crazy George. I shoulda' thought of that.
"Crazy George" wrote in message ... Rick: One of the overlooked problems is mechanical hum from fluorescent lamp ballasts and power transformers. Disconnect the speaker(s). If the hum does not go away, look at these items. If it does, then it is likely the main filter capacitors in the amplifier. -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick.
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#6
November 22nd 04, 07:34 PM
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What crazy (?) George didn't mention is on the older Seeburg amps, the
amp. HV is shut down when the machine is not playing so it CAN'T be the amplifier creating the hum!!! Either the Latch Solenoid or the fluorescent ballasts... John :-#)# On Mon, 22 Nov 2004 01:29:53 GMT, "Jim Murphy" wrote: You're not so crazy George. I shoulda' thought of that. "Crazy George" wrote in message ... Rick: One of the overlooked problems is mechanical hum from fluorescent lamp ballasts and power transformers. Disconnect the speaker(s). If the hum does not go away, look at these items. If it does, then it is likely the main filter capacitors in the amplifier. -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick. (Please post followups or tech enquires to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."
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#7
November 22nd 04, 11:42 PM
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John:
I didn't mention that, as I have seen 'boxes in home use which have the amps wired to be hot all the time, and an external power switch added, to eliminate the tiny start delay. Not that it makes much difference, but somebody thinks it does. And, I don't have a good marker for models which have it and which don't. -- Crazy George Remove N O and S P A M imbedded in return address "John Robertson" wrote in message ... What crazy (?) George didn't mention is on the older Seeburg amps, the amp. HV is shut down when the machine is not playing so it CAN'T be the amplifier creating the hum!!! Either the Latch Solenoid or the fluorescent ballasts... John :-#)# On Mon, 22 Nov 2004 01:29:53 GMT, "Jim Murphy" wrote: You're not so crazy George. I shoulda' thought of that. "Crazy George" wrote in message ... Rick: One of the overlooked problems is mechanical hum from fluorescent lamp ballasts and power transformers. Disconnect the speaker(s). If the hum does not go away, look at these items. If it does, then it is likely the main filter capacitors in the amplifier. -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick. (Please post followups or tech enquires to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."
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#8
November 23rd 04, 07:52 AM
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yes, that's correct, my amp hi-voltage does shut down after the last
record plays. I believe only the heaters (filiments) are left on. Either way, I still get hum from the speakers (I dissconnected one and the hum left from that one). I'm off the next couple days and can try the various suggestions you all have made. Rick. "Crazy George" wrote in message ... John: I didn't mention that, as I have seen 'boxes in home use which have the amps wired to be hot all the time, and an external power switch added, to eliminate the tiny start delay. Not that it makes much difference, but somebody thinks it does. And, I don't have a good marker for models which have it and which don't. -- Crazy George Remove N O and S P A M imbedded in return address "John Robertson" wrote in message ... What crazy (?) George didn't mention is on the older Seeburg amps, the amp. HV is shut down when the machine is not playing so it CAN'T be the amplifier creating the hum!!! Either the Latch Solenoid or the fluorescent ballasts... John :-#)# On Mon, 22 Nov 2004 01:29:53 GMT, "Jim Murphy" wrote: You're not so crazy George. I shoulda' thought of that. "Crazy George" wrote in message ... Rick: One of the overlooked problems is mechanical hum from fluorescent lamp ballasts and power transformers. Disconnect the speaker(s). If the hum does not go away, look at these items. If it does, then it is likely the main filter capacitors in the amplifier. -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick. (Please post followups or tech enquires to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."
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#9
November 23rd 04, 03:41 PM
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Rick:
Interesting. Be sure of that fact before proceeding further. DIsconnect all speakers. If the hum goes away, then you have some sneak path, sometimes incorrectly referred to as a ground loop in the speaker wiring. Finding that will require careful examination of the wiring of the speakers and the output transformer and associated terminal strip(s). I hope you have a correct and complete schematic. Good luck! -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... yes, that's correct, my amp hi-voltage does shut down after the last record plays. I believe only the heaters (filiments) are left on. Either way, I still get hum from the speakers (I dissconnected one and the hum left from that one). I'm off the next couple days and can try the various suggestions you all have made. Rick. "Crazy George" wrote in message ... John: I didn't mention that, as I have seen 'boxes in home use which have the amps wired to be hot all the time, and an external power switch added, to eliminate the tiny start delay. Not that it makes much difference, but somebody thinks it does. And, I don't have a good marker for models which have it and which don't. -- Crazy George Remove N O and S P A M imbedded in return address "John Robertson" wrote in message ... What crazy (?) George didn't mention is on the older Seeburg amps, the amp. HV is shut down when the machine is not playing so it CAN'T be the amplifier creating the hum!!! Either the Latch Solenoid or the fluorescent ballasts... John :-#)# On Mon, 22 Nov 2004 01:29:53 GMT, "Jim Murphy" wrote: You're not so crazy George. I shoulda' thought of that. "Crazy George" wrote in message ... Rick: One of the overlooked problems is mechanical hum from fluorescent lamp ballasts and power transformers. Disconnect the speaker(s). If the hum does not go away, look at these items. If it does, then it is likely the main filter capacitors in the amplifier. -- Crazy George Remove N O and S P A M imbedded in return address "Rick Force" wrote in message om... Hi All, My 222 has a low level constant hum. Volume setting has no affect and the amp is in the muted condition. Is this some kinda grounding problem? Amp was just serviced. Where do I look? This has a 2 blade ac cord. Thanks, Rick. (Please post followups or tech enquires to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."
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#10
November 23rd 04, 07:16 PM
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This is starting to sound like a filament shorted to a cathode and/or
grid of an output tube...that is the only way I can see a hum sneaking into the speakers on a Seeburg amp with no B+... John :-#)# On Tue, 23 Nov 2004 09:41:10 -0600, "Crazy George" wrote: Rick: Interesting. Be sure of that fact before proceeding further. DIsconnect all speakers. If the hum goes away, then you have some sneak path, sometimes incorrectly referred to as a ground loop in the speaker wiring. Finding that will require careful examination of the wiring of the speakers and the output transformer and associated terminal strip(s). I hope you have a correct and complete schematic. Good luck! (Please post followups or tech enquires to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."
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