Rotel RMB-1075 noise issue

Options
jflail2
jflail2 Posts: 2,868
in Electronics
Hey guys:

A buddy of mine has a Rotel RMB-1075 that he picked up for cheap. Apparently it was cheap for a reason, as when we plug in source cables, there is an instant, very extremely loud noise, like 100+dB static hum combined. If we unplug RCA cables = no noise.

Another friend suggested an AC input filter cap(s) may be bad, so I'm curious if anyone knows how we could go about testing that, and if bad, how difficult it is to replace.

The unit has no ground built into it - Polarized AC input.

Any input would be appreciated.

Thanks!

2007 Club Polk Football Pool Champ

2010 Club Polk Fantasy Football Champ

2011 Club Polk Football Pool Champ


"It's like a koala bear crapped a rainbow in my brain!"
· Share on FacebookShare on Twitter

Comments

  • SCompRacer
    SCompRacer Posts: 8,352
    edited April 2016
    Options
    I'd look at the RCA blocks ground into the circuit boards. I have a RB 985MKII which has a similar RCA input scheme. RCA blocks held to rear panel with screw, circuit boards attached to right and left side panel heat sinks. When it was shipped to me, the package was mishandled and chassis must have twisted, breaking a ground pin on one of the outer RCA blocks.

    Rather than search for an RCA block, I soldered a ground wire from board to RCA ground.

    An example of a board mounted RCA block.

    RCA-Connector.jpg
    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ * Signature Series Sonore Music Server w/Deux PS * Roon * Gustard R26 DAC / Singxer SU-6 DDC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *
    · Share on FacebookShare on Twitter
  • RamZet
    RamZet Posts: 792
    edited April 2016
    Options
    Ohhh Rotel!
    Try a ground loop isolater first, if I was part of the largest Rotel dealer/installers on the East Coast I would try this first because it works 7/10 times...so from what I have heard..

    Rotel is pretty cool too, give them a buzz and ask them!

    http://www.amazon.com/Raptor-GL15-Ground-Loop-Isolator/dp/B0009O19LQ/ref=sr_1_9?ie=UTF8&qid=1461623194&sr=8-9&keywords=ground+loop+isolator



    Edit*
    Is the thing bridged?
    (A lot of) Rotel amps have internal bridges, download the file for that amp and look to see if it has that feature.
    IF it does, they are just black pin covers that move from pins a b to b c.
    B&W CM9Classé Sigma
    · Share on FacebookShare on Twitter