Hi
So long time owner of the Marantz MM-8003 multi channel power amp. Had it from new and even if I have since purchased other amps I still use it to drive my rear channels in bi-amp mode. Now the issue is that I have had a re-occurring fault that have forced me to send it in for repair 3 times - every time with the same protection fault error.
Guess what - have now happened again. I have the service manual but honestly no direct clues except for measuring the whole amp.
I am guessing this is due to a component that should be replaced with a better version so that the error would not happen again. But, no clue available from the previous places that have repaired in the past and I honestly are getting a bit tired of paying for this.
So, does anyone have a clue to where this error is located? The amp will start but stop in protection mode with a fast blinking LED.
Would really appreciate if someone could give me a clue.. I know how to solder but not really equipped to do a complete fault finding (Yes, have measuring tools, multi meters etc. but still...)
THX
So long time owner of the Marantz MM-8003 multi channel power amp. Had it from new and even if I have since purchased other amps I still use it to drive my rear channels in bi-amp mode. Now the issue is that I have had a re-occurring fault that have forced me to send it in for repair 3 times - every time with the same protection fault error.
Guess what - have now happened again. I have the service manual but honestly no direct clues except for measuring the whole amp.
I am guessing this is due to a component that should be replaced with a better version so that the error would not happen again. But, no clue available from the previous places that have repaired in the past and I honestly are getting a bit tired of paying for this.
So, does anyone have a clue to where this error is located? The amp will start but stop in protection mode with a fast blinking LED.
Would really appreciate if someone could give me a clue.. I know how to solder but not really equipped to do a complete fault finding (Yes, have measuring tools, multi meters etc. but still...)
THX
Hi
Thanks - but have done that multiple times. In the beginning when the error occurred first (for the 4th time) I could sometime get it to complete the boot process by doing so - but not any longer. Have also tried the reset "buttons" inside on the circuit board.
Have looked for any items that looked damaged, burnt or otherwise out of place, but no luck.
I am sure someone who have worked on this model will say - oh, this is the %##% resistor or something similar that just goes somewhat off spec and throws a wrench in the system.
But thanks. Have done all the obvious stuff..
Thanks - but have done that multiple times. In the beginning when the error occurred first (for the 4th time) I could sometime get it to complete the boot process by doing so - but not any longer. Have also tried the reset "buttons" inside on the circuit board.
Have looked for any items that looked damaged, burnt or otherwise out of place, but no luck.
I am sure someone who have worked on this model will say - oh, this is the %##% resistor or something similar that just goes somewhat off spec and throws a wrench in the system.
But thanks. Have done all the obvious stuff..
You've done your homework. 🙂
Looking at different online places, you appear not to be the only one.
This must be a design error.
If the problem gets worse after each reset until you can't reset it anymore, I suspect a cap, perhaps indeed a resistor.
Very hard to find without company support.
Perhaps a seasoned Marantz tech over here knows how to solve the problem.
Hugo
Looking at different online places, you appear not to be the only one.
This must be a design error.
If the problem gets worse after each reset until you can't reset it anymore, I suspect a cap, perhaps indeed a resistor.
Very hard to find without company support.
Perhaps a seasoned Marantz tech over here knows how to solve the problem.
Hugo
Have you checked the firmware version? An update may fix it.
This is just a general suggestion that applies to all kinds of equipment simply beacuse firmware updates are for "bug fixes".
This is just a general suggestion that applies to all kinds of equipment simply beacuse firmware updates are for "bug fixes".
A possible solution could be looking at the solder side of the pcb's to see what has been replaced in previous repairs.
I was lucky one day with an amp I had sent to a service center because I couldn't find the problem.
It returned with a plastic bag containing one small 1k resistor.
I measured the faulty resistor and it was a perfect 1% 1k but they changed it and the amp worked fine.
I searched for new solderings and found the new 1k. Afterwords I was able to repair a few more of these amps.
Until today I have no idea what was wrong with these small critters.
Hugo
I was lucky one day with an amp I had sent to a service center because I couldn't find the problem.
It returned with a plastic bag containing one small 1k resistor.
I measured the faulty resistor and it was a perfect 1% 1k but they changed it and the amp worked fine.
I searched for new solderings and found the new 1k. Afterwords I was able to repair a few more of these amps.
Until today I have no idea what was wrong with these small critters.
Hugo
Sounds like there wasn't anything wrong with the resistor, probably just a bad solder joint on it.
I had four of these fairly new pro amps from a decent brand. Solder joints were perfect. Of course, on the second one I did a solder job, to no avail.
A new resistor cured it.
Slightly OT but it shows how some faults are nearly impossible to trace if one doesn't have support from the company.
A new resistor cured it.
Slightly OT but it shows how some faults are nearly impossible to trace if one doesn't have support from the company.
I have looked for signs of the part that was replaced but I honestly did not look right after I got it back. Today I am not able to see any specific signs of what was replaced. Also to be honest - it is not the easiest to get in to.
First photo is a stock photo, but the others are some I took. The board does not look that great but some of it could be lack of cleaning from the machine assembly.
But please add in with you thoughts and ideas..
First photo is a stock photo, but the others are some I took. The board does not look that great but some of it could be lack of cleaning from the machine assembly.
But please add in with you thoughts and ideas..
Oh - and before someone points to the trace line I did a resistance measurement and there was/is no resistance - so even if it does look like someone did add some solder to the trace line I am not sure it have any relevance now..
And yes, I should do a complete clean for old flux and other residues.
And yes, I should do a complete clean for old flux and other residues.
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If anyone wants to take a look at the service manual it can be found here:
https://www.manualslib.com/manual/2573890/Marantz-Mm8003.html
https://www.manualslib.com/manual/2573890/Marantz-Mm8003.html
That input board looks fine, although the pics aren't too sharp. Not easy, I know.
You could take a look at the power supply board but the power amp boards won't be easy to separate from the heat sink.
Edit: PSU won't be easy either, I meant the output board on the far-left.
Hugo
You could take a look at the power supply board but the power amp boards won't be easy to separate from the heat sink.
Edit: PSU won't be easy either, I meant the output board on the far-left.
Hugo
Another possibility is that they changed a complete board. In that case, looking for possible missing fasteners
as compared to the stock foto whould give a hint.
But where to get complete boards? 🙂
Hugo
as compared to the stock foto whould give a hint.
But where to get complete boards? 🙂
Hugo
My first thing to find a Marantz protection issue is to disconnect the amp boards (one at a time- with power off and unplugged) and then power cycle each time you disconnect an amp board, continue this process until the amp comes out of protection - your unplugged channel is the culprit.
Mindful that some Marantz versions have more than one amp channel per plug, but can get you focused on where to start looking closer.
Mindful that some Marantz versions have more than one amp channel per plug, but can get you focused on where to start looking closer.
Funny thing is that apparently the same issue is also present in later models. A quick search revealed similar issues on the MM-8077 models.
I found this video of a teardown of the MM-8077 which is very similar, but one less channel.
In fact looking at the video it is obvious that the some of the boards have been taken from it, but not equipped with all components..
I found this video of a teardown of the MM-8077 which is very similar, but one less channel.
Will try to pull boards but it is not a great way to do it, as some boards may be serially linked. I think maybe a better approach to start off with would be to pull the cables from the protection board. It have cables going to the sub boards but don't know if it will just say no if no signal is detected.
Also - found a story while searching for a solution of someone with similar protection start up issue. According to him he sent it off for repair.
The invoice came back and it was only parts for a few bucks/Euros or what ever your currency may be. The 97% of the repair cost was labour.
Now, he did had to send it back a couple of times before everything was working ok, but it still makes me think that this is design error that apparently is found in a number of Marantz's design.
Guess it would also be worth while to clean all the socketed cable connectors. They seem to be of a material that could be oxidized over time.
Also - found a story while searching for a solution of someone with similar protection start up issue. According to him he sent it off for repair.
The invoice came back and it was only parts for a few bucks/Euros or what ever your currency may be. The 97% of the repair cost was labour.
Now, he did had to send it back a couple of times before everything was working ok, but it still makes me think that this is design error that apparently is found in a number of Marantz's design.
Guess it would also be worth while to clean all the socketed cable connectors. They seem to be of a material that could be oxidized over time.
So, had time to look at the video I linked above. Turns out allmost the boards say MM-8003 - just only using 7 channels.
Beside one less channel it was not immediately obvious that they had changed the design - but there was one additional circuit board on top of the cooling tunnel. According to the video it is a "Signal Detection PCB"
Beside one less channel it was not immediately obvious that they had changed the design - but there was one additional circuit board on top of the cooling tunnel. According to the video it is a "Signal Detection PCB"
You can do as you wish but I can tell you that these connectors don't oxidize.
I would not assume these are a possible problem.
I keep thinking this will not be solved without a tip from a Marantz tech.
Nice video.
I have fixed 3-4 Marantz AVRs in the last year. I have been able to narrow down the issue by disconnecting the power cable to the amp boards - usually in an AVR it's 2-3 channels, marked by FR, FL, CNT, etc. with Red and Black wires and a white connector. On a 9.2 AVR, there are 4 of these connectors (3 channels, 2 channels, 2 channels 2 channels) Disconnect them one at a time and power-on the unit, obviously being careful not to disturb anything else. Once you have it narrowed down to 2-3 channels, then you can locate the output plug and check the DC voltage when you power it on. If it is >2 Vdc then you have found the problem channel.
Then check the outputs in diode mode - AVRs use Darlington's, so you are looking for ~1v forward bias compared to a normal BJT of 0.6-0.7mV. I generally can't find the bad Darlington in circuit, so I end up unsoldering the legs and testing - if memory serves me, I have always easily found one of the outputs shorted B-E.
Look at the picture attached - not 100% familiar with your amp, but I circled the connectors that should be the amp board connections - disconnect and see if you can get it to come out of protection.
Then check the outputs in diode mode - AVRs use Darlington's, so you are looking for ~1v forward bias compared to a normal BJT of 0.6-0.7mV. I generally can't find the bad Darlington in circuit, so I end up unsoldering the legs and testing - if memory serves me, I have always easily found one of the outputs shorted B-E.
Look at the picture attached - not 100% familiar with your amp, but I circled the connectors that should be the amp board connections - disconnect and see if you can get it to come out of protection.
