20 Most Recent Marantz SR-7400 Receiver - Page 6 Questions & Answers

Hi Neville. go to this link and its the manual this might help you out. Marantz SR6007 Owner Manual Troubleshooting Or this link might help you out. How to reset Marantz sr6007 to factory reset Google Search

I think your radio is as much computer as radio. Computers are everywhere and contain delicate CMOS circuitry - easily damaged by a power surge such as often accompanies a power outage. Surge protectors should be used to provide a measure of protection, although it is possible a software fault has been caused by the sudden interruption of supply.

That will have knackered the main power output device(s) located on the big heatsink. If they are transistors you should be able to tell which are faulty as a meter on the pins will give a full scale deflection, just like it was a piece of wire. There could also be physical signs of damage such as parts blown apart or burning.

Is the AMP grounded to the other components?

Is the amplifier being overloaded by the speakers, generally if they shut down like this its because the amp can't supply enough power to the speakers or there is an issue with the wires being to light gauge.

Here is the entire service manual with lots of troubleshootnig ideas...Good luck! Marantz SR6003 Service Manual

I'm an authorized service center for Marantz although I mainly work on vintage equipment, according to the manual the code your getting is for speaker impedance imbalance , but if you don't have speakers hooked to it then you have issues with one of the channels output stages, it may not be something you can fix yourself unless you have some fairly advanced electronic skills

It could be the amplifier but most likely it’s going to be either the connections or a power supply issue. Do you have anything plugged into the same outlet? What type of power strip are you using. The amp will usually go into a protect mode as to not damage anything before it would create the environment to cause a blown speaker. I know that with your model, along with multiple others, have had issues with the power board needing replacement.

Check power plug wires and replace the fuse and check if the unit has fuse on the rear and replace it.

If the device works on other speakers then it is probably working as it should. You need to check if the is an issue with the speakers that cause it to cut out. Make certain they are the right Ohms for the Marantz. Check the connections to them. It could be that a safety device is clicking in to protect them amp due to some overload problem, caused by the speakers themselves. It might even be one speaker that is playing up. Try testing one speaker at a time, by not having the other connected and the balance control only to the one connected.

http://irebuildmarantz.com/catalog/product_info.php?products_id=34 The symptom you describe could be a failing filter capacitor. It appears to be a common problem with this unit. The above link is a source of replacement parts, and or assistance in getting it repaired. Increasing the volume increases the voltage in the amplifier output circuits, which increases the stress on the filter capacitors. If one is breaking down it could cause a harmonic oscillation that would be a whistle. Hope that helps.

Thermal cutoff is operating. There is excessive heat being generated on the heat sinks of the Amp. This happens when there is a shorted output transistor or a speaker load changing.

hi charlie. not sure if this link will help you out,or you could try ebay. replacement volume control rm0254022 for marantz 2250b Google Search

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

If it is a twist type knob that regulates the volume control they can often brake so you will need to take it off to inspect it you can do this by pulling it directly towards you ( a small screw driver placed behind it can help to get it off ) then you will be able to check to see if it is broken or not or if you can then control the volume by turning the shaft that the knob was meant to be attached to , a small amount of epoxy glue should fix the knob back onto the shaft if this is the problem .