Hello,
Was hoping someone could help me figure out what might be the problem.
I have a Marantz pm6005 that I have stopped using because the right channel would produce no sound or almost no sound. Sometimes if I turned the volume all the way up I could barely hear it. I swapped the speaker cables, tried different sources (digital/analog), different speaker outputs (A,B), cleaned the volume pot, and also replaced the volume pot.
But the problem persisted. Sometimes it would work for a few hours or days then randomly it would stop.
About 1.5 years ago I took it to a repair shop and they kept it for 3 weeks to see if they could reproduce the problem and, according to them, it never happened while they had it. I picked it up and that same day the problem popped up in my system. At this point I gave up on it and started to use a different amp.
I have some time now to really look at it again and would like to be able to locate the problem and fix it if possible, however I'm not sure how to approach this.
Any help would be appreciated.
Regards,
R
Was hoping someone could help me figure out what might be the problem.
I have a Marantz pm6005 that I have stopped using because the right channel would produce no sound or almost no sound. Sometimes if I turned the volume all the way up I could barely hear it. I swapped the speaker cables, tried different sources (digital/analog), different speaker outputs (A,B), cleaned the volume pot, and also replaced the volume pot.
But the problem persisted. Sometimes it would work for a few hours or days then randomly it would stop.
About 1.5 years ago I took it to a repair shop and they kept it for 3 weeks to see if they could reproduce the problem and, according to them, it never happened while they had it. I picked it up and that same day the problem popped up in my system. At this point I gave up on it and started to use a different amp.
I have some time now to really look at it again and would like to be able to locate the problem and fix it if possible, however I'm not sure how to approach this.
Any help would be appreciated.
Regards,
R
Try using the headphone jack and see if the problem is also present when you loose the right channel.
Tried the headphones and it is the same.
No sound from right channel, only sound coming in from the left.
No sound from right channel, only sound coming in from the left.
That rules out the speaker output relay since you are still having the same problem with the headphones.
Check the PCB for bad solder joints since you have an intermittent problem. Other than that, it requires a good tech to locate the problem.
Check the PCB for bad solder joints since you have an intermittent problem. Other than that, it requires a good tech to locate the problem.
It seems to me that if your service agent was honest, really did operate the amplifier for a significant period over the 3 weeks but found no problem, any fault you still have must be associated with your connections or settings.
If that's not the case and the service agent just played it for a day or continuously at some low level, to satisfy themselves that there was no intermittent problem, it's possible that they missed your fault. It could be down to an open circuit or even a short or temperature dependency, anywhere in a thousand solder joints, connectors or possibly faulty components. It's seldom possible to guess what could be wrong when there are so many possibilities but few records of consistent intermittents in late model products.
What likely needs to be done, is trace the circuits back from the signal input connector to the output power stage, through the various boards and sections to the input sockets to determine where the output audio stops. You don't need anything sophisticated to do that. A film capacitor of 0.1-1uF @ 250V or more rating, a short probe lead, an RCA connector lead cut from a discarded stereo lead, a ground lead for the earth shield, connecting clip and an adjustable line level signal source such as some CD players, radios etc. have. The pic shows all that is needed for a basic tester though I suggest something safer, like using an insulating plastic tube to contain the connections and cover all open wiring rather than a chopstick 😀
Use a steady hand with the probe such that you only connect to the appropriate test points identified from the service manual schematics. Take care to adjust the line level up from lowest level first to cover the various signal levels normally expected in the amplifier without blowing your speakers or phones away at max. volume or being too quiet to hear.
Marantz PM6005 - Manual - Stereo Integrated Amplifier - HiFi Engine
If that's not the case and the service agent just played it for a day or continuously at some low level, to satisfy themselves that there was no intermittent problem, it's possible that they missed your fault. It could be down to an open circuit or even a short or temperature dependency, anywhere in a thousand solder joints, connectors or possibly faulty components. It's seldom possible to guess what could be wrong when there are so many possibilities but few records of consistent intermittents in late model products.
What likely needs to be done, is trace the circuits back from the signal input connector to the output power stage, through the various boards and sections to the input sockets to determine where the output audio stops. You don't need anything sophisticated to do that. A film capacitor of 0.1-1uF @ 250V or more rating, a short probe lead, an RCA connector lead cut from a discarded stereo lead, a ground lead for the earth shield, connecting clip and an adjustable line level signal source such as some CD players, radios etc. have. The pic shows all that is needed for a basic tester though I suggest something safer, like using an insulating plastic tube to contain the connections and cover all open wiring rather than a chopstick 😀
Use a steady hand with the probe such that you only connect to the appropriate test points identified from the service manual schematics. Take care to adjust the line level up from lowest level first to cover the various signal levels normally expected in the amplifier without blowing your speakers or phones away at max. volume or being too quiet to hear.
Marantz PM6005 - Manual - Stereo Integrated Amplifier - HiFi Engine
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I would check Q6002, if You can remove it. This muting transistors are able to make quite intertesting problems.
The headphone out test is not very good, as it use them some signal as the speakers.
Sajti
The headphone out test is not very good, as it use them some signal as the speakers.
Sajti
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My feelings is that the technician did not play it significantly, since I have tried different cables (power, speaker) and different speakers and various other combinations.
Thanks IanFinch and sajti I will look up the service manual and begin probing. This will probably take me some time as I am relatively new to all this.
Regards,
Ricardo
Thanks IanFinch and sajti I will look up the service manual and begin probing. This will probably take me some time as I am relatively new to all this.
Regards,
Ricardo
You checked solder points for cable connections from and to volume/tone pcb already ? Move these cables a little or touch/tap connectors.
A lot of people suspect output relays and replace them for no apparent reason. The headphone test I suggested rules this out as the likely source of the right channel missing problem. This normal troubleshooting method is called process of elimination.
The OP already replaced the volume control potentiometer without any proof that it failed. My suggestion simply avoided the early demise of another likely working part being replaced just because.
Q6001/6002 emitter and collector connections are flipped on the schematic. Emitter should be tied to A_GND for the muting action to work properly. I seriously doubt that muting transistor Q6002 that is configured incorrectly and operates at 3.3V maximum will cause the audio to disappear completely on one channel. 3.3mA flowing from the base to collector of Q6002 when muting is engaged is not going to kill it.
The schematic is OK. Check some information about the muting transistors:
https://www.electroschematics.com/9660/muting-transistor-attenuator-circuits-2sc2878/
Sajti
I got my hands on a loaner basic scope and started tracing the signal from the input to the main board to the volume board. It was OK until the volume board.
Once at the volume board I could trace the signal into the volume pot but not out.
I have attached a picture of what I checked. The input signal was going through R5001 and R5002 before going into the pot and both checked out ok. After the resistors they go into the pot at pins 7 and 3 and they are supposed to come out at pins 2 and 6. I get a signal from 6 and across capacitor C5001. I don't get anything out of pin 2 or across capacitor C5002.
I had another cheap pot from eBay and switched it out thinking something must be wrong with the pot I had put in but the new one has the same problem.
So I am at a loss, these pots are cheap ones from eBay 50K as well and 8 pins. Do the pins for different pots differ from what was there originally? Could this be why I am getting nothing out? Or am I looking at this completely wrong.
Once at the volume board I could trace the signal into the volume pot but not out.
I have attached a picture of what I checked. The input signal was going through R5001 and R5002 before going into the pot and both checked out ok. After the resistors they go into the pot at pins 7 and 3 and they are supposed to come out at pins 2 and 6. I get a signal from 6 and across capacitor C5001. I don't get anything out of pin 2 or across capacitor C5002.
I had another cheap pot from eBay and switched it out thinking something must be wrong with the pot I had put in but the new one has the same problem.
So I am at a loss, these pots are cheap ones from eBay 50K as well and 8 pins. Do the pins for different pots differ from what was there originally? Could this be why I am getting nothing out? Or am I looking at this completely wrong.
An externally hosted image should be here but it was not working when we last tested it.
I think I realized what'g going on. I did not notice that the pm6005 has "loudness" button and on the volume pcb pins 4 and 8 are wired into the loudness circuit. So the pot I replaced it with did not have loudness built in so the pins don't match up correctly with what is on the pcb.
I am looking for a pot that can fit but no luck finding one yet that has loudness. I might just have to wire the pot in using long wires to match up the correct pins. Hopefully this will work.
I am looking for a pot that can fit but no luck finding one yet that has loudness. I might just have to wire the pot in using long wires to match up the correct pins. Hopefully this will work.
The ones with Loudness taps are usually special order devices, so you wont easily find one. I would go with your plan of using wire.
Yes I think I will stick to the wires. I will try it out on the weekend.
I got a quote back from Marantz and they want $50 for a replacement pot, ouch.
I got a quote back from Marantz and they want $50 for a replacement pot, ouch.
I didn't want to open a new entry for the same problem. I am currently having the same issue on my marantz pm6005. It seems there is no way to solve without the original part.
Hi folks this is also happening on my PM6006. Was actually listening to a new vinyl and sent it back because one channel was not represented the way I remembered. Hilarious. The amp is not playing the right channel. It does work if you bypass the tone controls (“source direct”). Same in headphones and on speakers.
