Marantz 2270 loud popping noise

phire

New Member
Hi guys,

My Marantz 2270 developed a problem where the sound begins to pop loudly then it disappears completely. No sound from the aux inputs or fm radio, and no sound with another set of speakers. If i turn the unit off for 10 minutes, it goes back to normal, but after a few minutes, the problem repeats itself.

Do you guys know what kind of problem this is, and if it can be a expensive one to fix?

Thanks.
 
If it happens regularly like that and then repeats after turning it off and then back on it is most likely a bad transistor(s) .
Maybe on of the differential input pairs.

Bob
 
Sounds like something is overheating and/or drawing too much current causing the protection relay to kick in. It will likely take a tech to search for the problem. Finding a good one in your area is the trick. Don't know how hard that might be to find in Portugal, but even in the U.S. it may require shipping the unit to a qualified person. Of course, if you are handy with electronics and have some equipment,there are lots of experienced members here on AK to help you track down the problem. Good luck!
 
You could get a can of freeze spray(component cooler) and try to pin down which transistor(s) are acting up if they're accessible.

Bob
 
Welcome to AK!

You can narrow down the likely circuit board where the popping is originating. For example if the popping is in one channel then it may be one of the main amplifiers, which is where the differential pairs are located. Or if it is in both channels then the power supply becomes suspect. It is probably hard on your speakers when you do this test? But it will be telling to know if the popping happens in one channel or both.

Then the specific component(s) on the board will need to be identified and replaced. If the issue has been narrowed to one board then applying freeze spray can do that. Some tools and disassembly required to find, soldering required to replace. It does not sound like you are thinking of doing it yourself? It may not be an expensive fix in the hands of an electronics tech, the trick is finding one near you.
 
The popping is only in the right channel. Earlier today i left the unit with a tech, i'm hoping to have an estimate tomorrow. Wish me luck! :)
 
If it happens regularly like that and then repeats after turning it off and then back on it is most likely a bad transistor(s) .
Maybe on of the differential input pairs.

Bob

I second this. PNP input pairs can present exactly those symptoms. Common on the 2270, usually accompanied by protection circuit going in and out of protection.

Hopefully, the tech figures it out. We usually replace them with a pair of KSA992, heatshrinked together with a dab of thermal paste between them.
 
Althought it doesn't exactly match the background of the OP's problem, I would like to add some experience I made with exactly the same as the reported symptoms on a Marantz 4270. My reason for adding this here is that both receivers are quite similar and when I searched for a solution regarding the "loud popping noise" on a Marantz where even the protection relays switch off ("sound disappears for some seconds"), I stumbled over this thread because it comes closest to at least the symptoms I had on the 4270.

Description: So, yes, the initial problem was that after switching it on, the receiver began to produce heavy pop noises over the speakers on both channels after just a few minutes. Speaker protection switched the relays off for a few seconds. The pop noise came back a few minutes later, but went quieter the warmer the receiver was. It eventually disappeared for the time the machine remained switched on. The noise increased with »bass« turned up (and vice versa) and became very quiet with pre and main amps seperated.

Diagnostics and therapy attempts: I found defective caps in the power supply stage (especially the glued ones, but I replaced them all), replaced all the caps in the sound control stage, replaced one relay, also the eight differential input pairs of the main amp (they actually had significantly different amplification factors; I replaced them with 2SA1015), but the problem remained.

Finally and accidentally, when touching the power supply board, I realized that "jiggling" the cooling plate with its two 2SD331 a bit back and forth immediately triggered the pop noise activating the speaker protection. I checked for cold solder joints but could not find any. Yet after resoldering the whole board, the noise finally disappeard completely.

Having found the cause, it is easy to tell why this must be a (more or less) common problem. The cooling plate heats up and cools down, and the way the power supply board is constructed, it inevitably bends the solderings and junctions of and around the voltage regulators. Some recommend to restore this board in any case, and I think that this far from being exaggerated. Besides, it remains a very good receiver, most other caps still had at least their initial values.

Hopefully this might help someone else in the future.

Cheers
Thomas
 
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4 week with a pretty darn good repair guy. He left it on for days. No pop. I picked it up after 5 weeks No charge. This one I'm going to have to figure out. I keep notes on the pops and I am tilting toward the protection relay its self. I am reading Thomas, and will do that 1st. Heading south for the winter so the story will continue I hope...
 
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