Rock Ola Amp hum
Q&A about all types of jukeboxes: Wurlitzer, Seeburg, Rock-Ola, AMI, and more.
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mb9513
Topic author - Senior Member
- Posts: 116
- Joined: Sun Nov 20, 2011 8:34 pm
- Location: Clinton, Iowa USA
Hi all, my rock ola 464 has a hum. so concluded filter caps were the problem. I know these jukes have goofy problem with grounds, so i went through all of those making sure they were snug. i have replaced ALL of the electrolytics in the amp and still have the 60 cycle hum. i have the total cap kit so am wondering, can a 60 cycle hum come from non electrolytic caps? i know that the seperate power supply has 3 caps in it can they also cause the hum? It has gotten so severe now that i cannot power it up for fear of damaging something else. This is one of the most frustrating problems i have ever encountered. getting ready to scrap it out if can't get solved. Thanks in advance. Mark
Mark, 60Hz hum is a straightforward issue.
Does hum vary w/volume control setting?
Does it go away when the pickup plug is removed?
What is the state of the wiring to the volume control?
Given that the power supply is full-wave you will have 120hz w/faulty filters. This is an audio level problem with either shielding or ground connections.
If damaging the speakers is a concern during troubleshooting, just put the cabinet speakers on a low wattage tap.
On this schematic: http://www.verntisdale.com/schem/461-70a.JPG -that appears to be position 1 or 2.
Rob/NYC
Does hum vary w/volume control setting?
Does it go away when the pickup plug is removed?
What is the state of the wiring to the volume control?
Given that the power supply is full-wave you will have 120hz w/faulty filters. This is an audio level problem with either shielding or ground connections.
If damaging the speakers is a concern during troubleshooting, just put the cabinet speakers on a low wattage tap.
On this schematic: http://www.verntisdale.com/schem/461-70a.JPG -that appears to be position 1 or 2.
Rob/NYC
"If we believe absurdities, we shall commit atrocities" -- Voltaire
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DoghouseRiley
- Senior Member
- Posts: 630
- Joined: Thu Apr 16, 2009 9:48 pm
- Location: North-West England
I'm digressing a bit, as lots of people with less knowledge than others read this board.
This probably will not apply here, but sometimes, what you might think is a hum from the amplifier can actually be from the one, two, or more ballasts, for the fluorescent light fittings.
This probably will not apply here, but sometimes, what you might think is a hum from the amplifier can actually be from the one, two, or more ballasts, for the fluorescent light fittings.
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I don't mind if you don't like my manners, I don't like them myself, they're pretty bad, I grieve over them on long winter evenings.
I also had this hum on my rockola 414 .
Turns out the cartridge was not centered in
It's holder do to to the play in the original
Two screws holding the cartridge centered.
Cartridge was touching one side of headshell.
Two new screws and cartridge alighned
Properly took care of hum. Just a thought
George
Turns out the cartridge was not centered in
It's holder do to to the play in the original
Two screws holding the cartridge centered.
Cartridge was touching one side of headshell.
Two new screws and cartridge alighned
Properly took care of hum. Just a thought
George
Hi
I also had a bad hum on a nsm jukebox where the music was totally inaudible, the problem area was a faulty tonearm cartridge,i'll pm you and forward an extract from an earlier rockola dealing with amplifier hum, might be of some use
regards
clones
I also had a bad hum on a nsm jukebox where the music was totally inaudible, the problem area was a faulty tonearm cartridge,i'll pm you and forward an extract from an earlier rockola dealing with amplifier hum, might be of some use
regards
clones
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