Hi, My Marantz SR4200 goes into protect mode about 45min after cranking the volume up to party mode, ie above '0'. It is getting worse slowly. Ok at lower volumes. Something seems to be overheating, never used to do this when new... could it be a dry joint on output trany's.

There are 2 causes of the problem that you describe. One is the input signal is too high and is over driving the amp. The other is the output impedance is dropping due to short circuit etc. There is no adjustment on the protection circuit. It is possible that a weak sensor is present or a bad transistor etc, but you need special equipment to check that.
http://www.eserviceinfo.com/downloadsm/40697/Marantz_SR4200.html

Sounds like a bad speaker. Do you have more than one speaker hooked up to a single output?

Probably not. Marantz does not supply replacement boards, so you can't just put a new board into it to replace what was damaged.

The Amplifier was failing and that's why you were getting the crackling noise.

Most receivers have an Auto Protect that shuts the system down and goes into Protect mode at the first signs of failure or overheating, usually indication by 'Protect' on the display.

I'm presuming from your post that you never got any indication that the unit was shutting down to protect itself and has just failed, so I'm presuming that this facility isn't fitted on this model.

Depending on you Technical ability it could be an easy repair (replacing the complete PCB or some PCB components). Your only other solution is a visit to a service engineer.

Unplug all of the speaker wires. Switch it on. If it still says "protect" then the problem is internal within the receiver. If it stops going into protect mode with speakers disconnected, then the problem is possibly blown (shorted) and or incorrect speakers causing it to trip.

no it doesnt but it does have Optical Digital Output


http://reviews.cnet.com/av-receivers/marantz-sr4200/1707-6466_7-7052167.html

Check out the sound menu on the TV you might not have it switched to digital out, or have the wrong audio mode.

Check all your speaker wires carefully. Chances are good that a braid has crossed from + to - and causes the unit to protect itself. This is a very common problem! everyone's done it at some point. Check connections at both the receiver side and the speaker side. If you still have a problem, post a comment and I can help you troubleshoot further. Hope this helps.

Either there is a bad capacitor in the protection unit or you can find the wire that goes from volume control to protection unit and unplug it.
You can also try turning the volume all the way off before turning on, then slowly turn up from there

I use a Logitec Harmony 520 programmable remote. I pay 80$canadian.
http://www.logitech.com/index.cfm/440/371&cl=ca,en&hub=1?selectedcrid=440&selectedcid=371