Marantz 4400 trips protect circuit sometimes.

[Robisme]

A guy that I sold a receiver to asked me about another one he has. A Marantz 4400. He says it works great then all of a sudden there is a pop in both channels then it goes into protect. Sounds to me like dc getting to the outputs. Odd it's in both channels. Does the 4400 have independant amp boards like the 4300?
Could this be a power supply problem?.
Later it will be fine again, then it repeats the problem.
Any thoughts will be helpful.
Thanks.
Rob

 

[EchoWars]

If the pop is present in all channels, it suggests a power supply issue. I'd think about overhauling the regulator.

 

[Fred Longworth]

Since you said "both channels" and since the 4400 is inherently a quad unit, that suggests you may be operating the unit in bridging mode.

Be aware that in bridge mode neither side of the speaker is grounded to chassis; rather a speaker is hooked between two power amp outputs running out of phase.

EchoWars indicated that the power supply is likely the problem. I agree. That is the point of commonality. Most likely you have a transistor failure.

Fred Longworth

 

[EchoWars]

Isn't troubleshooting via crystal ball exciting?:yes:

 

[Robisme]

I am not sure what mode he is running it in. Seems like every time I sell a receiver I did some work on, the buyer has questions about another piece of gear they own. I try to help out best I can and you guys are a great resource. But like you said, crystal ball. I will relay the info you supplied.

Thanks again.

Rob

 

[davef350]

Sell me a 4400 at a resonable price and I promise to never contact you if there is a problem!!!
Don't you think the Sansui 9090 or 9090DB are most terrific receivers?

Even though this is the Marantz forum I have to say from my limited experience with both I would have to go with one of those Sansui models.

Dave

 

[jblmar]

Isn't troubleshooting via crystal ball exciting?:yes:

Just looked in my crystal ball and saw the Protection Circuit board as the possible source of your problem. Common to all four channels. I had the same problem with my Marantz 300DC. Played fine, then...BOOM!! Out of both speakers. Turned out to be a bad solder on the board. As the amp heated up, the solder joint issue occured.


Ron