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 Post subject: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 7:33 am 
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Location: Garland, Texas
Hello,
I recently purchased a marantz SR 4000 that powers up and and gets meter readings for tuning on a.m. and f.m. but absolutely no sound. A fellow enthusiast that used to work on these units said something about that if both power modules were not operating well then no sound would come through. Has anyone out there worked on this type of unit before? Should I spend the $75.00 on two power modules or is there something else on this unit I should look at first?
Thanks,
Rudy


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 10:29 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Albuquerque, NM 87123
Check all the fuses first.

You can make a reasonably quick test of the modules: unsolder all the pins of one module and power up; if you get sound on one channel, then the module that is still soldered is good. No sound? Resolder the first and unsolder the second.

You could have two bad modules if there is still no sound.


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 12:05 pm 
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Location: Utica, NY 13502 (USA)
Rudy18D wrote:
.....is there something else on this unit I should look at first?
I would clean all switches and controls first. Do the LED power meters show movement? Do you hear the speaker relay click shortly after power-up? (Black, cubical thingy near the large, black filter caps.)

Image

Image

Dave


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 1:08 pm 
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Hi Johnnysan,
How many fuses are there on this unit to test? I will do the unsolder test this evening.
Thanks for the reply.
Rudy


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 1:16 pm 
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Hi Dave,
The LED's show movement occasionally. Most of the time they do not. I never hear the relay clicking to the speakers.
I will clean all the switches tonight and report back.
Thanks for the quick reply.
Rudy


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 1:16 pm 
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Location: Albuquerque, NM 87123
I see in that photo that there is a preamplifier module (sometimes called a voltage amplifier); that may be bad. It's the smaller module between the two amplifier modules.


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Wed 16, 2018 2:23 pm 
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Joined: Aug Fri 12, 2016 1:49 am
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Location: Houston, TX
Vintage service manual.

Modern version.


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Fri 18, 2018 12:18 pm 
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Location: Utica, NY 13502 (USA)
I found it interesting that Marantz made two, completely different models labeled SR-4000...one being a black-faced, home theater type. I assumed that the author has an earlier, legacy-styled Marantz.

Dave


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Sat 19, 2018 9:50 am 
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Joined: Jun Fri 22, 2007 12:54 am
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Location: San Diego
This phase of Marantz amplifier design has created a lot of frustration for today's techs.

The most common failure is that the driver IC goes bad, largely because it runs hot irrespective of volume level, and thus undergoes major thermal cycling. When it fails, there's either an intermittent and large offset voltage, or a continual and large offset voltage. This error condition is perceived by the protection circuit as a hazard to one or more speakers---so it refuses to fire the protection relay, and hence there's no sound.

Less commonly, one of the two power amp IC's will fail, again triggering protection mode.

Unfortunately original IC's are close to impossible to find. There's a plethora of bogus copies of the originals. THESE DO NOT WORK. Especially with the driver IC, the frequently compensation is often very different from the compensation for the original device. When installed, these "knockoffs" often go into rail-to-rail oscillations at frequencies like 200 kHz---and sometimes they incinerate in front of your eyes---even to the point where they can explode!

Be very careful here!

Fred

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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Sun 20, 2018 11:41 pm 
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Hi Fred,
Thanks for the heads up Fred. I have replaced the two audio power amplifier modules and the relay still did not open. So I think your first thought is correct. If I manually actuate the relay I hear very faint but discernible audio on AM and FM. The analog meters work but the LED's still do not work.
Any idea on a part number or equivalent for the driver IC and a place to start looking? This unit is very clean and looks great, I would hate to throw it out just because of one IC.
Thanks,
Rudy


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Mon 21, 2018 12:25 am 
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Joined: Jun Fri 22, 2007 12:54 am
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Location: San Diego
To the best of my knowledge, there exists no reliable source for genuine driver IC's of this type. I think they've been used up. The Chinese knockoffs simply don't work. Either they distort horribly or they cause a high-frequency oscillation.

I wish I could bring you better news. If you can find a driver IC, you'll likely find it through an European source. At my repair shop, we're increasingly ordering parts from Europe---Germany, UK, even Bulgaria! We scour eBay on a daily basis.

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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Mon 21, 2018 12:35 am 
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Location: Garland, Texas
Fred,
I also saw that some folks are replacing the STK3062 IV with a newer STK3082 III. Supposedly the newer 3082 has a higher ouput rating and a higher input voltage but will work with in this scenario and run cooler. Comments?


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Mon 21, 2018 3:52 am 
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Joined: Jun Fri 22, 2007 12:54 am
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Location: San Diego
It won't be an original 3082III. My comments stand.

We've seen scores of machines that use this or similar IC sets, and only extremely rarely have we been able to find replacement driver devices that actually work. Since I own a repair shop, I can't install inferior or non-operational parts. The part needs to be an original. Whether it's a 3062IV or a 3082III, the overwhelming majority of parts with those numbers on them are Chinese knockoffs. The web is flooded with these.

As I said, we're found that the only source for originals---and even then it's sketchy---is European sellers. The same situation is going on with laser pickups for CD players.

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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Mon 21, 2018 4:22 am 
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Joined: Aug Fri 12, 2016 1:49 am
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Location: Houston, TX
This is claimed to be original.

They have a money back satisfaction guarantee. Might be worth a shot.


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Mon 21, 2018 4:24 am 
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Location: Garland, Texas
Well dang. Shame a unit in such good shape otherwise can't be saved.
Thanks much for taking the time and sharing your expertise.
Rudy


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 Post subject: Re: Marantz SR 4000 No Sound
PostPosted: May Mon 21, 2018 4:29 am 
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Location: Garland, Texas
Thanks Vin. I don't have much to lose. I will give it a shot.
Thanks!
Rudy


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