Marantz 4240 faulty channel

[jackmot]

Hi!
I have a 4240 which the Front Left channel is giving me some problems.When you turn on the Marantz it starts making a cracking sound that completely blocks out all the audio from that channel. This sound does not change with volume or any configuration, the only thing that changes is that if you put the unit to 40W 2X (instead of 17W 4X) the sound also goes to the Front Right channel.
The sound may sometimes randomly disappear for a moment but eventually it comes back.
Thanks for the help guys

 

[catrafter]

Have you tried cleaning the rear panel LOCAL/REMOTE switch?

Also Never cycle the power mode switch with the receiver turned on.

Tom

 

[jackmot]

Yeah, I have tried that but the problem persisted
Thanks

 

[daveo50]

Take a look at your amplifier assemblies. They are the ones attached to the output transistor heatsinks. I had a problem with my 4230 that had a light scratching sound on power up then went away. I had the unit apart to fix another issue and I noticed that I had a small hum in the left front channel. Problem was a failed electrolytic. Find where the amplifier board is fed with power. Power goes through a resistor (I can't remember the value) then filtered with a 47uf capacitor. The 47uf capacitor had failed. Replacement removed the hum problem and the light scratching sound during power up also went away.

I know there are some differences between the amplifier sections of both the 4240 and 4230 but you may get lucky. Hope this helps.

And, Tom is correct - Do not switch the power settings when the receiver is powered up. Bad things can and usually happen if you do that.

Good Luck.

 

[jackmot]

Hey!
I´ll try to check those electrolytics when I get home. Is it possible that the problem are the output transistors? any prefered brand for those transistors?
BTW: I just changed the C804 because it was getting hot, hope that helps the problem a bit.
Thanks!!

 

[jackmot]

Hey!!
After many months I FINALLY figured out what was wrong.
Between the C002 and the C003 capacitor filters there was a bad soldering point.
if any of you guys have a similar problem I suggest you resolder the bridge between these 2.
Hope this helps someone.
Have a great day