Marantz 2220B garbled sound from right channel

[Winks]

Hey everyone,
I am new here and I just acquired a Marantz 2220B. The body is clean, all the lights work, the blue looks correct, and have no static when I turn any knob or switch. The amplifier sounded amazing when I tested it out and purchased it. Unfortunately, this all changed when I got her home and started to use it. The right channel started to produce a garbled sound that was unclear and progressively got worse as I increased the volume. I had tried to do a little detective work as I disconnected the right speaker from the main line and connected it to the right "remote" output, same distorted sound. I had then plugged in a set of headphones to the front jack, and she played clear as a bell with no sound issues.

Does anyone have any ideas of what may be wrong with my Marantz and how I may fix the problem?

Thanks

 

[Winks]

FYI the DC readings are 6mV Left and 15mV right

I had also tried a second set of speakers and obtained the same distorted sound so I know its the amp

 

[ChrisMarantz]

The 2220 is a capacitor-coupled receiver, so the DC offset reading must be taken with a dummy load connect to the speaker terminals. (no speakers connected)

Is there distortion on all inputs including the tuner?

I would clean the selector switch and tape monitor switches first, just in case it's something simple.

The problem could also be from dirty and worn contact in the relay on the amplifier board

 

[Winks]

Hi Chris,

Sorry not sure what you mean by dummy load. The distortion is present in all inputs. I had pulled the bottom plate and cleaned all of the switches and pots with Nu-Tone Control cleaner (could not fine Deoxit locally but was told its the same stuff) and still no luck.

Going to have to find out how to check the relay.

Also don't know if this helps but I notice that the audio volume on the tuner is louder then my other inputs.

 

[bktheking]

8ohm 100w+ resistor is a good dummy load. Measuring DC offset on a cap coupled amp is a waste of time. I'd have to study the schematic but chances are the headphones are tapped at the outputs, in other words, after the relay (update-tapped at the main/remote speaker switch). Wouldn't shock me to learn you have a blown output. Easy enough to test, swap the outputs between right and left channel- pay attention to the PNP/NPN arrangement and reinstall the mica's. Make sure you give the unit enough time to discharge before attempting (30 mins or so)

 

[wmgwizard]

If its anything like my 2238 you may find a shorted transistor and burned resistor.

I had distortion and reduced output on one channel just like you.

You have to lift the amplifier module from the main chassis and look carefully for a burned resistor feeding one of the small transistors connected to a small black heat sink on the lower corner.

About $4 in parts and an hour or so and my 2238 was singing as sweet as ever.

Good luck with yours, keep us updated on what you find.

 

[bktheking]

If a resistor is cooked that would be an issue swapping outputs (test them out of circuit to avoid further damage) - the resistor cooks cause the outputs shorts and draws more current- the resistor becomes a fuse essentially.

 

[bktheking]

On the 2220b i'd attempt to test the .47 ohm transistors - 2 watts, most of the stock ones were green. There are also 10ohm transistors connected to the drivers that i'd test.

 

[wmgwizard]

The resistor in my unit was R758, a 10ohm unit. It failed because the transistor H724 shorted. I believe it was a driver transistor, before the outputs.

 

[Winks]

Thanks for all the help guys but I think I may be in a little over my abilities on testing these items. I had pulled the top cover and found the amplifier board (pictures attached) nothing looks burned on it except the purple capacitor seems to have leaked something. I tried unscrewing the board and get a better look but was unable to budge it too far as it had many wires restricting motion. I think I am going to have to search for a good and reasonable repair person in the Toronto area.
Thanks again

 

[Dr Tinear]

I worked on a direct-coupled Heathkit AR-19 with a similar problem. It sounded fine when it was first turned on, but the sound from one speaker got distorted and garbled after a few minutes of listening. It turned out that the output transistors on that channel were electrically leaky. The drivers were okay, so I replaced the outputs on both channels and have had no further trouble with that receiver.

 

[Thumper]

If it's anything like the 2245/70, the headphones are tapped off of the main amps, so if the headphones sound fine, I'd think it might be the speaker switch? Push that sucker in and out about 50 times and see if anything changes.

BTW that purple cap didn't leak - that's glue holding it to the board.