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Loud, Low Hum When Marantz Turned On

Kevbo

Kevbo

Member
I have been using my Marantz 2240B for about two years now with little issue (all have been fixed). And today, which was just another morning for me to turn it on to listen to music while working, a loud, low-grade hum is coming from the speakers. Music still plays fine, but there is the hum on top off it all.

The hum is also present in the headphones, even when I turn the mains off.

I am not great with electronics, so I'm not sure where to start looking. Is this a ground issue? Any thoughts would be appreciated! Thanks.

~ Kevin
 
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Power supply as stated above and main filter caps might be suspect too. What exactly was "fixed" when it was serviced?
 
Does the hum occur on all inputs ? FM/Phono/Tape/Aux
Do you use a turntable and if so is the ground wire connected ?
 
Fairlane said:
Power supply as stated above and main filter caps might be suspect too. What exactly was "fixed" when it was serviced?
Click to expand...
I serviced it with my dad, replacing all the bulbs, restringing the tuner, and I had an issue with one of the speakers going out after a few minutes. Turns out I needed to really clean the Monitor button. That was advice from someone on here after a lot of trial and error, and that worked perfectly. I have also Deoxed all the pots about a year ago.
 
mikey99 said:
Does the hum occur on all inputs ? FM/Phono/Tape/Aux
Do you use a turntable and if so is the ground wire connected ?
Click to expand...
A turn table is connected, and the ground wire is also connected to the back of the Marantz from the turn table. I use the Marantz every single day, and today was no different than any other day, except the hum is now there. The equipment wasn't moved, touched, anything to have caused this.
 
Yeah it is time to replace the basics Kevbo.

Lots of real experts on here to help you through if you decide to take it on yourself.

Can you test the preamplifier from the amplifier section to at least narrow it down possibly?
 
Does moving the balance control cause the hum to come from only one speaker ?
Knowing that might help isolate to preamp or main amp. Also you might try removing
all the input cables and antenna to see if that makes any difference.
 
mikey99 said:
Does moving the balance control cause the hum to come from only one speaker ?
Knowing that might help isolate to preamp or main amp. Also you might try removing
all the input cables and antenna to see if that makes any difference.
Click to expand...
Moving the balance control does nothing. The humming is still coming out of both speakers. Removed and replaced all cables, and humming is still there.
 
Fairlane said:
Yeah it is time to replace the basics Kevbo.

Lots of real experts on here to help you through if you decide to take it on yourself.

Can you test the preamplifier from the amplifier section to at least narrow it down possibly?
Click to expand...
I will definitely need to take it on myself.....I'll see if my dad is up for another weekend project with me. :-) Please excuse my ignorance, but how would I test the preamp over the amplifier section to narrow it down? That questions may tell you exactly how little I know about electronics like this. Computers, I can rip them apart and put them back together blindfolded, however.
 
Fairlane said:
Yeah it is time to replace the basics Kevbo.

Lots of real experts on here to help you through if you decide to take it on yourself.

Can you test the preamplifier from the amplifier section to at least narrow it down possibly?
Click to expand...
And as far as "replace the basics", are we talking capacitors and whatnot? Would this only be for the PSU, or around the whole board?
 
Your unit has pre-out main-in jumpers. Do a quick search to see how to test them independent from each other.
Do you have another amplifier?
 
I took a peek at that website. Looks like the caps are kind of "no-name" brands. I suggest Mouser or Digi-Key, whichever is closer. They have great search tools. I'm a fan of Nichicon caps and for power supplies I like the PW and HE series but others may work out. A general rule is to keep the same capacitance value (the uF number) and use the next highest voltage range if it works out. For example, if the circuit has a 50V rated cap, I use a 63V part. Sometimes Marantz cut it close on their voltage selections!
 
Be aware that the values on the schematic may not be what is in your unit. I did a quick rundown on the electrolytic caps in the 2240B manual. The values on the left are in uF/vDC. The part numbers are from Mouser.

220/63: 647-UPM1K221MHD6
100/50: 647-UPW1J101MPD
22/35: 647-UHE1H220MDD
330/50: 647-UPM1K331MHD6
470/16: 647-UHE1E471MPD
10/50: 647-UPW1J100MDD
47/16: 647-UHE1E470MDD
220/10: 647-UHE1E221MPD
 
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