Hi,
Hope that someone could help me figure out what might be the problem. Thanks.
I have a Marantz pm15s2 that I have been using for 7 years. Recently, the left channel would suddenly produce no sound or ‘sound lost’ if I played heavy bass music or play it at loud volume(above 35db). When I encountered this, I just press on “speaker” button on front panel to switch speaker output off and switch back on again, then it back to normal. But the same problem will occur again if play heavy bass & loud. It is quite annoying as I have to press on speaker button off and on whenever I encounter this... However, no such issue if playing at low to medium level(<45db).
Could it be a relay problem that it require cleaning?
Hope that someone could help me figure out what might be the problem. Thanks.
I have a Marantz pm15s2 that I have been using for 7 years. Recently, the left channel would suddenly produce no sound or ‘sound lost’ if I played heavy bass music or play it at loud volume(above 35db). When I encountered this, I just press on “speaker” button on front panel to switch speaker output off and switch back on again, then it back to normal. But the same problem will occur again if play heavy bass & loud. It is quite annoying as I have to press on speaker button off and on whenever I encounter this... However, no such issue if playing at low to medium level(<45db).
Could it be a relay problem that it require cleaning?
Anythings possible I suppose although normally relay problems tend to be worse at lower levels, higher volume pushes more current through the contacts and temporarily allows it to work.
Easy enough to check though by simply looking at the signal before and after the relay. Try giving the relay a gentle tap when it does it again.
Easy enough to check though by simply looking at the signal before and after the relay. Try giving the relay a gentle tap when it does it again.
It doesn't seem to be the familiar pattern for dirty relay contacts where low signal levels are the problem and turning up the volume clears it. Unless the signal drop is accompanied by distorted sound, I'd say its a deliberate attenuation caused by a different type of problem.
This is a complex, very different style of amplifier to the 1970s-90s types we are accustomed to seeing here when they fail. There are signal level relays as well as a power relay and so much more.....
I think I would be careful and consider following the published faultfinding procedure very carefully before assuming the old ways will uncover the mystery. Microprocessor control brings a whole different way to consider faultfinding and repair options. Check the manual out and see what's involved: Marantz PM-15 - Manual - Stereo Integrated Amplifier - HiFi Engine
This is a complex, very different style of amplifier to the 1970s-90s types we are accustomed to seeing here when they fail. There are signal level relays as well as a power relay and so much more.....
I think I would be careful and consider following the published faultfinding procedure very carefully before assuming the old ways will uncover the mystery. Microprocessor control brings a whole different way to consider faultfinding and repair options. Check the manual out and see what's involved: Marantz PM-15 - Manual - Stereo Integrated Amplifier - HiFi Engine
Sorry, you guys misunderstood.. kindly read my post again. I would like to clarify:
The amp is normal when playing at low to medium level(below 45db).
It will only lost sound on left channel when I play it loudly(above 35db) or heavy bass music (above 45db)
Thanks ..
The amp is normal when playing at low to medium level(below 45db).
It will only lost sound on left channel when I play it loudly(above 35db) or heavy bass music (above 45db)
Thanks ..
Your 1st post was very clear 🙂 and as you mentioned 'could it be a relay problem' I replied saying that the symptom reported doesn't fit the norm for relay issues, however you can of course confirm that by doing as suggested. Ian seemed to have a similar view that the fault as described didn't really sound relay related.
What you need to do as a generalisation is to first look at the input signal to the power amp sections on a scope and then working from there, see exactly where the volume drop is occurring.
I haven't looked at the circuit and I'm not saying it will necessarily be an easy fault to fix, but a few minutes work with a scope will at least allow you to determine where the audio is being attenuated and to investigate why the action of switching a speaker on and off restores normal operation.
What you need to do as a generalisation is to first look at the input signal to the power amp sections on a scope and then working from there, see exactly where the volume drop is occurring.
I haven't looked at the circuit and I'm not saying it will necessarily be an easy fault to fix, but a few minutes work with a scope will at least allow you to determine where the audio is being attenuated and to investigate why the action of switching a speaker on and off restores normal operation.
Heavy current and the amp goes nuts. It only has one pair of output transistors so forget that it will do bass heavy music - it will not. Well what if you just bridge the relay to eliminate the relay contacts problem. I would check the bias current, DC offset since the amp uses DC servo, solder joints for cold joints, some connections might be loose or oxidized. You might have problems with overly sensitive protection. It is rather complex circuit so read up first what it does, especially the DC servo. And please no 4ohm load and heavy bass, it wasn't designed for it (not enough doped silicone ��😉 - needs second pair of out transistors and bigger heat sink for more umph.
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Playing at 35db should be ok right. Didnt know that pm15s2 so unreliable. Currently running Focal 1027Be, with 91db sensitivity.
1990s Musical Fidelity A100(20W class A?) drives it loud and heavy bass without any problem.
1990s Musical Fidelity A100(20W class A?) drives it loud and heavy bass without any problem.
It shouldn't be unreliable, and a single pair of suitably rated transistors can get you 150W rms into 8 ohms.
Your problem with this amp needs you to make some basic tests to at least determine where in the chain the fault lies. You will have to get 'hands on' and do the measurements.
Your problem with this amp needs you to make some basic tests to at least determine where in the chain the fault lies. You will have to get 'hands on' and do the measurements.
What about factory reset? Anyone know how to factory reset this amp? Since this modern circuits are so complex n complicated. Probably factory reset will solve the prob
The service manual details how to put the unit into 'Test Mode' and goes on to say that this clears the internal memory and initialises the unit.
I'm wondering if the problem could be with the MAS6116 chip which is an analogue volume control under uP control.
It should be easy to check for this simply by monitoring the levels into and out of this chip.
I'm also going to suggest the reset might be worth trying... you just never know with these kind of things. If it has no effect then its time to look at signal levels.
It should be easy to check for this simply by monitoring the levels into and out of this chip.
I'm also going to suggest the reset might be worth trying... you just never know with these kind of things. If it has no effect then its time to look at signal levels.
I wouldn't rule out defective capacitors, since the amp was manufactured when there was a "bad capacitor" alert circulating around - affecting everything electronic made between 2002 to 2006 or so.
Those pesky capacitors showed up in everything - I know, I've had to replace hoardes of them for years.
If the vender of caps had these bad caps, and dealt with Marantz, well, I rest my case.
Those pesky capacitors showed up in everything - I know, I've had to replace hoardes of them for years.
If the vender of caps had these bad caps, and dealt with Marantz, well, I rest my case.
Hello wiseoldtech, defective caps that you meant are two big caps or those tiny tiny one? In fact, I m also thinking of recap those tiny tiny caps after 8 years using it by changing it to better quality sort of caps rated 105C. But those 2 big cap 18000uf 63v Super Through caps are specifically designed for Marantz by Nichicon. Guess won’t be that 2 big caps problem right?
Wiseoldtech. Thanks for remind me, I remember I was having problem with PM7200 decade ago, distortion on left or right channel, can’t recall. I just simply recapped all the caps on both power amp board and preamp board with Panasonic FC/FM series 105c without bothering to test on signal circuit, as I m no good in it at all. Then problem solved. Hmmm, this brand lots of problem. Will try again if factory reset won’t solve the prob
Since the amp plays well, I doubt the main filter caps are at fault.
More likely faults are in the smaller caps among the boards.
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