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Need Help With My Rockola 484
I just picked up a Rock-Ola 484 from guy a guy that told me that the machine was tempermental after you moved it and that for him over the years, after it was moved, it would make a loud humming sound for about 5 minutes or so after the first plug in. I moved it all in to my house and it did do that loud humming sound the first time I plugged it in and it went away. The problem is that it is still sporadically making this loud humming sound when it's truned on and a lot of times, right in the middle of playing a song from one of the 45's. Any ideas of what the problem is or how to stop this? Thanks...
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#2
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Need Help With My Rockola 484
On Nov 26, 9:25*pm, sbiceps77
wrote: I just picked up a Rock-Ola 484 from guy a guy that told me that the machine was tempermental after you moved it and that for him over the years, after it was moved, it would make a loud humming sound for about 5 minutes or so after the first plug in. *I moved it all in to my house and it did do that loud humming sound the first time I plugged it in and it went away. *The problem is that it is still sporadically making this loud humming sound when it's truned on and a lot of times, right in the middle of playing a song from one of the 45's. *Any ideas of what the problem is or how to stop this? *Thanks... -- sbiceps77 Where does the hum come from? Speakers? Or is it mechanical. Rob |
#3
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It seems to be coming from the speakers...
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#4
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Need Help With My Rockola 484
On Nov 27, 2:13*pm, sbiceps77
wrote: It seems to be coming from the speakers... 'Rob in NYC[_2_ Wrote: ;663015']On Nov 26, 9:25*pm, sbiceps77 wrote:- I just picked up a Rock-Ola 484 from guy a guy that told me that the machine was tempermental after you moved it and that for him over the years, after it was moved, it would make a loud humming sound for about 5 minutes or so after the first plug in. *I moved it all in to my house and it did do that loud humming sound the first time I plugged it in and it went away. *The problem is that it is still sporadically making this loud humming sound when it's truned on and a lot of times, right in the middle of playing a song from one of the 45's. *Any ideas of what the problem is or how to stop this? *Thanks... -- sbiceps77- Where does the hum come from? Speakers? Or is it mechanical. Rob -- sbiceps77 Ok, if the hum is coming from the speakers it points to either power supply filtering or poor ground connections. Is the hum a deep bass note -same as when you touch the center connection of an RCA cable that is connected to an amp. 60hz. If so you might try wiggling the various connectors that go into the amp chassis and see is that causes any change. Does this type of hum occur if you unplug the pickup or move it's wire. Or is it a somewhat nasal higher pitch, this would be 120Hz From your description it seems that the hum can occur even when the machine is just sitting there, plugged in but no playing. That points to amp power supply. Again, try moving wires and bumping the chassis of the amp to reveal a loose connection If there are any filter capacitor cans on the amp, try tapping those. We are looking for a loose connection or poor solder joint. If nothing definitive comes of this you will have to remove the amp and, depending on your comfort in dealing with electronics, secure a schematic and trouble shoot or find someone willing to take it on. I don't have a schematic for Any R-o's but Vern Tisdale has one for the 478-481 series and they may be the same or "close enough". http://www.verntisdale.com/schem/478-81.JPG Part 1 http://www.verntisdale.com/schem/478-81a.JPG Part 2 with power supply section. If this is the same in yours, I notice an edge connector on the "Power supply P C Board assembly" These connectors are often the cause of problems. If you are able to open the amp, you might try removing this boards and cleaning the copper edge connector with either contact cleaner or just rubbing alcohol then reseating it.. But It sounds like a simple change of filter caps is in order. Rob |
#5
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Thanks for the help, I will give it a go. Also, it is a dull, deep bass hum, not high-pitched at all...
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