Any Audio Video system experts out there?

[unrepentant]

I have a Marantz 7702 MkII preamp/processor. When I use it "normally" it sometimes drops (mostly) the right front channel- once in a while, it'll be a different channel that drops out- the rear left channel or even the side left channel- but no sound will come at all from one channel out of the 7.1 setup I have as my home theatre audio setup.

This occurs whenever I turn the Marantz on after it's been off for several hours. One time, out of frustration, I slapped the metal casing, and the processor instantly came back "whole" and the unit performed as it should with all channels working. I've repeated this process several times and the results are constant... if I turn off the unit for several hours, and then turn it on, at the start-up, one channel will be missing but if I slap the unit, the channel will recover and they all work as they should. I did this 6-8x before I decided to leave the unit on 24/7.

That's an obvious remedy--leave the unit on 24/7; I've been doing that for the last 3 weeks and it performs flawlessly. (I've tested this failure twice more during that time by cycling the power and still the process is predictable) The closest authorized Marantz service station is ~170 miles from me; they theorize that a new circuit board needs to be installed (costing ~$410).

What harm can I do to the unit leaving it on "permanently"? Is there any way to know how much I'd shorten the processor's service life by running it 24/7 ?

Thank you.

 

[Vodoun daVinci]

I came from the commercial Audio Video Systems Integration field and worked on literally thousands of Systems where everything is powered on 24/7. Usually stuff lasts longer when it's not being powered up and down all the time.

VooDoo

 

[eflyguy]

Sounds like bad soldier joints. When it warms up, stuff expands, sometimes making better contact. If it's using DSP, it's possible it could be a chip that was not flowed properly - that would make more sense than multiple output stages. Finding an intermittent fault is time consuming.

Slapping it is the giveaway, but also not good for it long-term.

 

[XikoPlavi]

I would not leave it on permanently. These type of solid state systems are not that expensive and don’t last forever. Just get something new would be what I’d do. However, I know that may not be an option.

So, I’d take the cover off of it and use an air compressor and blow it out. Don’t blow super hard air on it but a decent Amy of forced air.

Undo any circuit connectors and blow them out and reconnect them

If it’s been sitting in a humid area this kind of thin happens.

Could also be the rca or hdmi ports on the backplane are going bad

Try new cables. Cut the ends off your speaker wires and redo them and use banana connectors.

Go into the display on the receiver and just set it to stereo 2 speakers for a while and just play the tv that way and see if it still happens

Make sure you don’t have your speaker wires backwards or your inter connects (if you have other components connected with it).

These type of receivers sometimes just go and die.

It could also be the way you have the digital sound configured in the menu system. Start from basics and redo all that (like I said, go back to just stereo mode and make sure just 2:1 works with normal TV.

My best advice though is to get rid of it and get something more high end like McIntosh or accuphase.

I don’t really use solid state anymore. I use tubes (but I don’t do the surround sound thing no more).

 

[Maggot]

Sounds like bad soldier joints. When it warms up, stuff expands, sometimes making better contact. If it's using DSP, it's possible it could be a chip that was not flowed properly - that would make more sense than multiple output stages. Finding an intermittent fault is time consuming.

Slapping it is the giveaway, but also not good for it long-term.

This or a deteriorating circuit board. Leave it on, or take it to a QUALIFIED repair shop. I checked and its a current unit, not cheap, of worth repairing.

 

[Maggot]

I would not leave it on permanently. These type of solid state systems are not that expensive and don’t last forever. Just get something new would be what I’d do. However, I know that may not be an option.

So, I’d take the cover off of it and use an air compressor and blow it out. Don’t blow super hard air on it but a decent Amy of forced air.

Undo any circuit connectors and blow them out and reconnect them

If it’s been sitting in a humid area this kind of thin happens.

Could also be the rca or hdmi ports on the backplane are going bad

Try new cables. Cut the ends off your speaker wires and redo them and use banana connectors.

Go into the display on the receiver and just set it to stereo 2 speakers for a while and just play the tv that way and see if it still happens

Make sure you don’t have your speaker wires backwards or your inter connects (if you have other components connected with it).

These type of receivers sometimes just go and die.

It could also be the way you have the digital sound configured in the menu system. Start from basics and redo all that (like I said, go back to just stereo mode and make sure just 2:1 works with normal TV.

My best advice though is to get rid of it and get something more high end like McIntosh or accuphase.

I don’t really use solid state anymore. I use tubes (but I don’t do the surround sound thing no more).

Tubes rule. I have all custom built, point to point wired phono stage, preamp, and amps ( I biamp horns with amps built with old Chicago and Peerless output transformers). The only transistor in my system are the ones regulating the speed on my Technics SP 10 Mk II turntable (no Cd player either, strictly analog.) What kind of gear you using.

McIntosh and Accuphase are great units, not cheap, and not the top of the line these days, but built to last.

 

[OldSalty2]

Eventually the slap won't work. Could be lots of things. Input or output signal from the preamp stage, something in the DSP circuitry etc.

What type of connections do you have from the preamp to the amp? Are you running a digital connection (optical, hdmi, coax) from the preamp to amp? Or discrete rca analog for each channel from the preamp to the amp? I didn't look up that model....

As for leaving something on. It may work for a while, even a long while, but all these components have a MTBF power on hours.

Best to get it serviced.

 

[HousePlant]

Three possible issues in order of what I expect as most likely:
1) Minor solder failure on processor chip or whatever is seeing the Ohm load of the speakers
2) Power supply connection or systemic failure (not providing clean power)
3) Processor chip failing

Either of these can be fixed by a qualified person. I have fixed a few myself along with some Samsung TVs. Might be worth a look yourself inside. Just unplug it, ground yourself, and don't touch anything.

 

[XikoPlavi]

I looked at this model you have and I can see you paid 2k+ for it probably when it was new. Seems like 2016 is when it came out. I’d guess you don’t have extended warranty.
As others have said at this point I agree. If you really want to save the amp then have it serviced

 

[OldSalty2]

Just looked up your preamp. I assume you are likely using rca unbalanced outs to your amp. Make sure they are connected securely. Especially if you are sliding the preamp into some sort of shelf where the rca cables could be binding / stressing.

Like someone posted above, walk through the basics first.

ex: Turn it all off, unplug the unit and clean the rca out posts with a qtip and tiny bit of isopropyl alcohol.

 

[OldSalty2]

Tubes rule. I have all custom built, point to point wired phono stage, preamp, and amps ( I biamp horns with amps built with old Chicago and Peerless output transformers). The only transistor in my system are the ones regulating the speed on my Technics SP 10 Mk II turntable (no Cd player either, strictly analog.) What kind of gear you using.

McIntosh and Accuphase are great units, not cheap, and not the top of the line these days, but built to last.

So I take it you didn't sell that system?

From what I recall, you take The Hide trophy for most impressive audio system lol...

 

[XikoPlavi]

Tubes rule. I have all custom built, point to point wired phono stage, preamp, and amps ( I biamp horns with amps built with old Chicago and Peerless output transformers). The only transistor in my system are the ones regulating the speed on my Technics SP 10 Mk II turntable (no Cd player either, strictly analog.) What kind of gear you using.

McIntosh and Accuphase are great units, not cheap, and not the top of the line these days, but built to last.

Yeah I’m never going back to solid state. Old school is the way. I know some people build their own tube amps and all the P2P circuitry. That’s an achievement for sure. I’m not that guy though I’d love to be taught or watch someone build one.

Currently I have a 80 watt prima Luna EVO 400 INT amp, Manley chinook phonostage preamp, VPI HW40 turntable with a soundsmith paua cartridge and focal sopra 3 speakers

And of course a rack for it to all sit on (solid state hyperspike).

All I do is records. I might get a DAC at some point and a CD player (doubtful though)

I’m looking to go to a 150 watts McIntosh MC1502 tube amp and matching preamp (old school 1960s design)

 

[XikoPlavi]

Ohh and for the record (no pun intended) I will admit I should have bought the technics SL-1000R turntable in hindsight, but I had other VPIs that I loved. It’s got to be direct drive for me and technics is the only other true high end direct drive turntable.

 

[NoDopes]

I'd take the cover off.. then lightly start touching stuff with a plastic dowel to find the culprit. Probably a simple resolder once found.
On the other hand I was considering mixing powders to make a custom burn profile so you may not Want to listen to my advice.

 

[Maggot]

So I take it you didn't sell that system?

From what I recall, you take The Hide trophy for most impressive audio system lol...

Getting older, downsizing. I sold the big bass cabinets, working on moving the horn part. Never fear, I still have a pair of Altec 604 E Super Duplexx speakers with a Xoover that will bi amp, in custom built cabinets, and all the front end.

 

[Maggot]

Yeah I’m never going back to solid state. Old school is the way. I know some people build their own tube amps and all the P2P circuitry. That’s an achievement for sure. I’m not that guy though I’d love to be taught or watch someone build one.

Currently I have a 80 watt prima Luna EVO 400 INT amp, Manley chinook phonostage preamp, VPI HW40 turntable with a soundsmith paua cartridge and focal sopra 3 speakers

And of course a rack for it to all sit on (solid state hyperspike).

All I do is records. I might get a DAC at some point and a CD player (doubtful though)

I’m looking to go to a 150 watts McIntosh MC1502 tube amp and matching preamp (old school 1960s design)

Nice stuff. I looked at the Prima Luna, I believe its all PtP wiring. Supposedly a really nice unit for the$$$. The only caveat I have is its made in fucking China and I refuse to buy communist stuff (if at all possible) no matter how good the deal.

The thing abut McIntosh is that while its not absolute top end, its damn near it,. The better stuff is really well built, will last a lifetime, and is a good investment; will hold value better than anything in the audio world. Theres a lot to be said for name recognition. If youre ever in the Virginia area give a shout, we'll have a beer and do some listening. Pming a photo of my current system, dont want to keep u\putting it up here. Sae for you Salty.

 

[Maggot]

Ohh and for the record (no pun intended) I will admit I should have bought the technics SL-1000R turntable in hindsight, but I had other VPIs that I loved. It’s got to be direct drive for me and technics is the only other true high end direct drive turntable.

Nice table but Ive heard the pointh and arm leave a bit to be desired.

You can pick up an SP 10 Mk II very reasonably, might want to have it checked over to make sure the chips that control the speed are all in spec. Pick up a plinth on Ebay for a couple hundred bucks, maybe a Kuzma arm, and you'll never want a belt/string drive again.

 

[unrepentant]

Thanks, Gents.

I'm running the XLR balanced connectors; the drop out occurs in either mode, RCA or XLR, and I've cross-checked amplifier and speaker connections too, by swapping out wires in all configs. I'm 99% sure the dropout originates in the Marantz processor.

Leaving it running 24/7 with a cooling fan for now. I'll check with the service center and see if they've got a source for the circuit board; last check in Nov was that they found one board in the USA with a Marantz OEM-inventory survey/check. If they have one, I'll drive it up there.

Years ago, I used to run a Mac stack, but as time went on, I moved away from McIntosh because I just didn't hear much advantage in "cream of the crop" expense versus non-Mac "nice" equipment. I stepped down to Krell, Pioneer Elite, Fosgate Audionics and Marantz without any troubles except for this one unit. Maybe I've got a tin ear, but my 20+ year old B&W N805s and SVS PB12 Ultra-2 woofer sound as good to me with these other OEMs as they did with the old Mac stuff. There's no doubt my old Mac stuff is still running, wherever it is; but the financial advantage afforded to me with "lesser" brands allows me to move up in tech... HDMI wasn't out when I had the Krell stack; XLR wasn't out when I had the McIntosh stack, etc; and I couldn't/didn't wanna "move up" and keep even with the costs either, especially since I was hard-pressed to hear enough difference to justify it all in my budget.

This is the only Marantz equipment I have; I bought it after I heard one work at a friend's house. Frankly, I can't hear any difference between it and the Krell Showcase it replaced. I just wish it was more stout.

 

[OldSalty2]

Seems like you have covered much of the basics. Would be difficult to get much further without tools, oscope, schematics, etc.

I assume the drop happens no matter what you choose as the input source?

Sounds like a trip to the doctor. May want to take both the amp and preamp to save a trip.

 

[n2ishun]

2 words.
Output relay

 

[XikoPlavi]

I always ran pioneer elite stuff when I was doing the 5:1 7:1 thing.

I still have them all and they work fine.

There is no perfect answer but i never really messed with taking them apart (especially the back plain). I mean taking the cover off is simple enough to inspect soldering and any amber lights. ..ETC

PM the guy that mentioned output relay. Maybe that’s a board or connection that can be worked on by you.

 

[unrepentant]

Thanks again to all ya'll.

Old Salty, I'm pretty sure it's not amplifier-related. When I was swapping cable connections to see if it was speaker related, I also swapped from one amp to another (I have three), other speakers dropped out also when I routed the Marantz RF-Out to those different channel speakers. Crossing amp connections didn't seem to indicate it to be the RF amp connection. Different sources don't matter either.

XikoPlavi, thanks for that suggestion; I've PM'd n2ishun--but as I told him, it's all voodoo to me--I'm afraid I'll let the magic smoke out if I crack the casing open. I'll get up the nerve and break out my plastic screwdrivers and go probing for loose boards and connectors. WOW, it's been decades since I used those...