20 Most Recent Marantz PM7200 2-Channel Amplifier Questions & Answers


One common explanation is the capacitors fail after a number of years. The lineage of these electrolytic caps usually last about 10 years or so with regular operation.

This is a disappointment and many PC's, top of the line receivers such as yours 10-15 years old are plagued with these failing capacitors.

Suggest if you are DIY replace all electrolytic. If not look for a electronics repair local and get an estimate.

the repair manuals are available.
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The capacitors does not have to leak to fail. Also check for open/cracked solder joints around the power supply and power amps.

I have repaired several PC's and receivers for these defects with only an inspection lamp and multi-meter.

Purchasing a used replacement of the same age will likely require similar repair. Some older units are more reliable?

Good solder skills are critical and if you DIY practice on scrap boards before attempting.
hope this helps?

Marantz PM7200... | Answered on Dec 15, 2016

Tip

Fixed amp won't turn on and click noise.


The amplifier would sometimes not turn on, when it did there was a loud click from one channel of the amplifier.

Reason.

Inside the amplifier there is a protection board that plugs into the amplifier, the design uses 3 x 25V 47uF capacitors charged up by 22K and 220K resistors.
As the amplifier ages with time, a parasitic resistance across each capacitor gets less and less, this means that the capacitor can not charge fully up and reach thresholds, in the **** design of a delay circuit. The parasitic capacitance is affected by the room temperature making the fault intermittent.

The pop sound is caused by DC offset, it was 25mV, this was nulled using a trimmer on the amp pcb to stop the click-pop sound, this offset could of damaged a loudspeaker.


on Jan 14, 2016 | Marantz PM7200 2-Channel Amplifier


The class A switch adjusts, via an optocoupler, the bias on the output transistors.
I would check the standard bias and class A bias adjustments.

Marantz PM7200... | Answered on Mar 22, 2014


Could be a power supply failure or a Power "On" switch failure.

Kev

Marantz PM7200... | Answered on Nov 24, 2013


Biggest cause an overload in the power supply or main output stages. Your perhaps looking for a shorted device. It might be burnt or damaged!

Marantz PM7200... | Answered on Nov 20, 2012


It's probably being governed by it's designed in desire to survive and avoid damaging speakers.

Generally speaking, an amp attempts to protect itself from heat, shorts, overloads and operator exuberance by refusing to turn on or stay on.

Overloads can be from excessive periods of high output or marginally low impedance loading by the speakers; and shorts would be wiring issues or a speaker blowing up.

You should be able to feel if it's hot. WHY is it overheating? Make sure it has sufficient ventilation on all sides and that vent holes are not blocked by dust balls. Ensure the fan (if equipped) is running as designed (some only operate on demand). Clean dust and debris from it.

If the amp comes back on after cooling, you're lucky. They only have so many self-protection cycles in their lives so continuously resetting or cycling their power without addressing the cause can do more harm than good.

If it protects immediately on a cool power up you should disconnect the speaker connections and try it 'naked'. If it comes up then diagnose which lead(s) are shorted. If it does not come up the problem is internal and should be left to an experienced and competent hands-on tech.

Check for loose speaker connections at the speaker as a possible root cause for intermittent shutdown.

Marantz PM7200... | Answered on Jun 23, 2011


Try wiggling the speaker cables where they connect into the PM7200. If it crackles get the shop to check for 'dry joints' in the unit. It is quite normal for things to look ok and to work perfectly in the workshop, but that is not a good test. Dry joints are quite difficult to spot and any soldered joint 'looks' ok, but if the soldering temperature is a bit off, usually on the low side where the solder is only just about hot enough to melt, it will result in a what we call 'dry joint'. It is not unfrequent to get this problem with production line processes as there are many factors on the assembly line that can effect the tip of the soldering unit. It can be as simple as someone getting up out of a seat and changing the air flow that then causes the soldering tip to cool slightly. We are taking 'parts' of a degree temperature changes. The shop should have equipment to test the conductivity of soldered joints. A light hand during testing is a prerequisite!

Marantz PM7200... | Answered on Mar 15, 2011


http://www.retrevo.com/support/Marantz-PM7200-manual/id/511bh847/t/2/
http://www.fixya.com/support/t409652-marantz_pm_7200
The top link is for a manual for your model. The second link is a Fixya link concerning "no power". I'm not sure why you are looking for fuse but, have to assume it's a no power issue.
http://livesupport.maybenow.com/Marantz
The above link is a support link for Marantz. Hope this helps.

Marantz PM7200... | Answered on Mar 10, 2011


hi,
First of all check the power at the socket to which you have connected the amp.If you are not aware of electronics, then do not go for a test with an amp like KI signature.
it will have a fuse in its inside. its only blow off if there is some fault inside the its circuitry. consult someone who is well equipped for the same.
ok

Marantz PM7200... | Answered on Feb 06, 2011


So something is making a hum inside the unit? Well the answer is to listen to what is making the hum, with your ear (a drinking straw held to your ear will help locate where it's coming from). Once you have found the part "huming" replace it. See if that cures it.

Marantz PM7200... | Answered on Jan 22, 2011


Try looking at the rear of the amplifier to see what the speaker load should be...it will be measured in Ohms...you will then want to look at the speakers to see what the impedance is on the speakers...if it is LOWER than what is on the back of the amplifier, then you have an impedance mismatch which is causing the amp to go into protect... If the speakers are in fact the proper impedance then you probably have a bad speaker...you can test this out by disconnecting one speaker and trying it,,,and then the other and so on...another thing to try would be to obtain another pair of speakers with the proper impedance to see if they work...now if you try all this and the amp still cuts out..them there probably is a problem inside the amp...I specialize in Vintage Audio so try these things first...if you have questions feel free to email at jcameo7270@yahoo.com

Marantz PM7200... | Answered on Dec 30, 2010


You can check the fuse with a battery and a bulb. Take the fuse out and use it to make a circuit with some wire, the battery and bulb. If the bulb doesn't light it has gone.
Apart from that other things to check are the power switch, to see if it works and the transformer.
It might be worth buying a cheap Ohm meter, if you haven't got one. You can check most of the parts in the power supply with it. By the way if the fuse has blown, buy a few as you might find it could blow again when you try it again. If it does you are looking at a device (such as a transistor) that as shorted and acting like it was a piece of wire. Which is easily found with an Ohm Meter!

Marantz PM7200... | Answered on Sep 28, 2010


Dear Sushant,    I do not think your use of an equalizer has caused any problems.  I will explain the proper use of the source/direct button.  This button's function is to monitor the output of a recorder connected to the record outputs of your amp.  When this button is pressed on the sound going to the speakers comes direct from the "source" (cd, radio tuner, phonograph etc.) when in the off position you can monitor the recording of whatever source is being recorded via the tape deck.  This switch must be off to record through the amps record outputs.    To test this, put a blank tape in the tape deck, choose the source as phono and place the dec in record/pause.  With the source direct button pressed on you should hear a change in volume when moving the amp's volume knob only.  When source direct is off you will be able to hear the output of the tape deck, so adjusting the tape deck's record level will also affect the volume coming out of the speakers.  more record level in/ more level out.!    Below is copied from page 9 of your user operation manual for Marantz's explanation of the source/direct button.  image.tiff
best of wishes, Michael Mittelsdorf

Marantz PM7200... | Answered on Sep 21, 2010


The preamp stage might be dead. Not much you can do but to bring it in. Make sure the input selector is on the right input.
Sometimes there's a "Monitor input" usually Tape2 input that overrides everything

Marantz PM7200... | Answered on Sep 01, 2010


Hi Paul;
There are one or more transistors failed in the output circuit
I would have tech look at the amp and see what the power supply is doing without spkrs connected

Marantz PM7200... | Answered on Aug 25, 2010


it sounds like your power surged maybe and it fried it check on the circut boards and see if you see any black spots like burns

Marantz PM7200... | Answered on Apr 27, 2010

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