Rumbling from Amp Rowe R-84

[MO Hillbilly]

Finishing up working on my Rowe R-84.  Mech. is now working great and recently received my computer control center back from Bruce at A & B Jukebox Repair.  They are great to work with! 

However, Just plugged in the amp and it makes a rumbling noise when you turn up the volume on the juke when a record is playing.  This is reminiscent of the old turntables that were ungrounded or sitting on a speaker?  Is this feedback or vibration?   I have four unshielded wires going to the cartridge.  This is the way it came to me.  Should these wires to the cartridge be shielded?  Grounding issue?  When i disconnect cartridge wires from the amp, I can turn up the volume with no bass rumble?  FYI, running an M44 Shure cartridge.  Thanks for you ideas.

[ami-man]

If you remove the input from the amplifier when it is playing does the rumble go away?

Regards
Alan

Alan Hood
ami-man
UK

[MO Hillbilly]

Hi Alan:
Thank you for your reply.  Yes, I can max. out volume with no rumble.

[MO Hillbilly]

Hi Alan:
Does this sound like an input or amp issue?  With record playing, I can remove the input and the rumbling goes away?  The tone arm wire is currently not shielded.  Would/could that cause the issue?  Thanks.

[ami-man]

Hello Mo,

The phono cable from the mechanism to the amplifier is normaly a dual screened cable with both screens going to the middle of the 3 pin phono connection into the amplifier.

Regards
Alan

Alan Hood
ami-man
UK

[MO Hillbilly]

Thanks Alan.  I will check that cable to make sure it's in good repair and hooked up correctly.

[MO Hillbilly]

Well, I decided to recap amp on this R-84.  I’ve done this several times on Rockolas, but not a Rowe.  Seemed straight forward with no real problems.  However, now I have no sound at all.  I do have the “thump” when I plug in amp.  I’ve checked the vol. control and cartridge input.  Any way to check mute circuit?  What else might I check?  Thanks.

[ami-man]

Which capacitors have you changed?

Regards
Alan

Alan Hood
ami-man
UK

[MO Hillbilly]

Hi Alan:
All electrolytic on the preamp and both driver boards.  I am double and triple checking them for polarity and cold solder joints.  Thanks for any further advice!

[ami-man]

Hello Mo,

I know its a daft question but have you got the volume control plug the right way around, are there wires in connection 1, 2 & 5 or have you made up a test volume control using pins 1, 3 and 5 (pin one is linked to pin 5 and goes to one side of a 10k log pot and pin 3 goes to the wiper on the pot.

Regards
Alan

Alan Hood
ami-man
UK