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Need help !! Contiuous "DUB DUB " sound from Yamaha CA 600 phono out..!!!

Y

yamahita

New Member
Guys I bought a Yamaha CA 600 amplifier to listen to my records..but when I plugged in the RCA jacks to the phono inputs and set the selector to phono the speakers gives out a continuous DUB DUB DUB sound.. i can hear the record playing but the sound is somewhat distorted. This amp's got two phono inputs one for MM and one for MC with an impedance selector and they both have the problem. And yes the turntable is grounded. Can anybody please tell me what might be the cause !!!!!
 
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Start with the basics first - clean all controls, switches, etc. Do the non-phono inputs work, or are they making the same noise? What sound is coming out of the headphone jack?
 
Thanks for the reply Electone.. I cleaned it all but there's no improvement..non-phono inputs are fine..tape inputs are fine... and the sound is coming even through the head phones..there's no decent person around here to show it to...that's why i'm trying to find and narrow it down to the most possible cause so I can fix it myself and see!!!
 
No Rub-a with your dub dub.:D

Do you know if your TT works on anything else ? Cart misalignment ?
 
Ha HA !! I was waiting for a reply from you.. so many members seem to recommend you on yammies. Well.. I have two TTs and they work fine with other amplifiers I've got. I plugged in both of them and checked.. the sound is still coming !!!! :(
 
Well at least its narrowed down to just the phono circuit. BTW I have no idea what " dub dub" sounds like.Does this strange noise appear in both channels? Check your solder connections within the phono section. RCA input jacks included. I'll have to dig up a schematic.
 
Is your modem or wireless router anywhere in the vicinity? Was experiencing the same issue, thought it was the amp but low and behold those pesky little digital devices from U-Verse were mucking up the works. Moved them away and problem solved.

I went so far as to purchase an outboard phono pre but the issue still persisted.
 
Thanks Kingshead.. my router is placed well away from the listening area and it's usually switched off when I listen. The DUB DUB sounds like... think of it this way... you are playing music and at the same time you plug in a mic and continuously tap it with your finger..a continuous bassy thud.. :)...thanks again for spending your time on this guys !!
 
Yes it is coming from both channels...I gave it to a tech here to find out what's wrong.. he said he cleaned it.. but I'm not sure.. do you want me to clean it .. again?? just to be sure ??
 
Check R443 on the function board. Its suppose to be a 22Ω fusible resistor.Measure the DC voltage at both ends of that resistor. Should be around 50 vdc.
 
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Does it happen when the turntable is not in motion? If it's only in motion you may be picking up noise from the turntable itself, maybe a subsonic filter would help.

BillWojo
 
thanks BillWojo.. I'm sure it is not something mechanical because this doesn't happen when I use the turntable with my other amplifier. Thanks again.. think I'll have to check all the semiconductors associated with the phono circuit.
 
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