Marantz 4140 Noisy LR Channel


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Staff member
QQ Supporter
Since 2002/2003
Oct 18, 2002
College Grove, TN
This 4140 amp was gone through "thoroughly" 7-8 years ago. Caps and such were replaced and LED lighting installed. Tone boards are pretty shot and hard to find at that time but I keep them flat anyways. The good times are impacted now by spitty transistor(s) or resistors similar to the Marantz 4270 thread from May 2022 I saw here a couple nights ago. When I changed to bridged (2CH) mode, it merely shifted all that noise into the LF speaker.

The facility I used back then is no longer interested in doing service work outside guitar amps, FX and PA systems. While I figure out how and where to get this serviced, I started thinking about my Marantz (bought new in 1977 and always trouble-free) 1040 stereo amplifier helping out for the time being. So I confirmed location of the 4140 rear pre-main jumpers and removed them. Then I disconnected the speaker leads for the rear channels. I placed the 1040 atop the 4140 and attached the rear speaker leads. Then I connected a cable from the 4140's rear Pre Outs to the AUX input of the 1040 amp. I played some FLACs thru the Oppo BDP-93 and within a minute or two I had sweet quad sound again.

I love some of this old equipment so much; the upkeep to have it in good running order is a price I must pay. Last week I was so happy that both my Moog Taurus pedals (T1 & T2 models) were working 100%, then the Marantz noise reared it's ugly head. Such is life and I'll do what it takes because when it works good, there's nothing like it. Here's a picture of the rescue on Marantz Mountain. <G>

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