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Troubleshooting a random crackle in a Marantz 2270

dragnalus

dragnalus

New Member
I've had my 2270 for over 20 years, and I had it re-capped about 8 years ago. It's worked great until very recently.

The right speaker channel, has a loud crackle that happens at random times. I'm trying to troubleshoot why this is happening, and am hoping folks here can help. Here is what I noticed:


- the crackle happens even when the volume is all the way down.
- the crackle happens regardless of what output is selected (Aux, Phono 1, Phone 2, Tuner, etc.)
- the crackle happens on on the right side channel. When I reverse the right and left the speaker wires, the crackle changes speakers, therefore it isn't the speaker - it's the receiver or the wire.
- the crackle happens regardless of whether the main speaker or remote speaker output is used.

I was thinking of buying some new speaker wire to see if that works. I'm praying it's the wire and not the receiver.

Can anyone shine some light on what they think might be happening?

Also, can anyone recommend some speaker wire that they like for the similar clamps? (I've always hated having to twist the end of a frayed speaker wire and jam it into the clamp thing... )
 
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First of all, welcome to AK!

2270 is a classic, mine will never leave. The problem is not your wires. Could be dirty controls, could be a noisy transistor(s).

First thing you should do is read this thread here.

https://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

Next you need to determine if after cleaning and the noise is still there if its coming from the preamp or the main amp board.

Do you have another receiver or amp with pre out main in capability to test with?
 
Thanks for the idea! Yes I'll get some DeOxit and give it a thorough cleaning. I'm haven't opened the case in probably 5 years or more, so it may indeed just need to be cleaned.

Unfortunately I don't have any other equipment available to use for testing.

This weekend I'll do the cleaning thing and see where that nets out. I'll post back here with any news of progress.

Cheers
 
Lots of real experts on here to help.

Might try working all the controls a bunch in the meantime. That might do the trick in lieu of a thorough cleaning with DeOxit.
 
Here's a couple of simple things you can try to isolate your issues to the Main Amp or Preamp, without test equipment:
  1. If you have some headphones, you can verify that it is not your speaker wires.
  2. You can use your cellphone or PC audio out to test the Main Amp if you have an adapter to go from your cellphone (or tape player) into the Main In jacks (with Pre Out-Main In jumpers removed). CAUTION: Just make sure your cellphone (or PC) volume is turned all of the way down or you will blow out your speakers since your receiver volume control will not be hooked up when you go directly into the Main In.
  3. If you are just listening for the crackling noise you might be able to hear it without plugging anything in just pull the jumpers out. If you still hear it, it's in the Main Amp... if you don't, it's the Preamp.
  4. Another possibility is the protection relay contacts being dirty, oxidized. You can try turning the receiver on/off several times (wait for the relay click is heard) to see if it improves.
  5. Last thing to try is to swap L & R channels from Pre-Out to Main In using RCA audio patch cables. Remover the jumpers and use the cable to patch from Pre-Out (L) to Main In (R) and Pre-Out (R) to Main In (L). If the crackle moves from R channel to L, then it is in the Pre-Amp. If it remains on the R, then it is the Main Amp.
  6. The last thing to try to determine where the problem is to press the Mono-L or Mono-R buttons, one at a time. See if the crackling goes away if one is selected. This will help isolate the area of the problem.
Hope this helps.
 
Pull the preamp to main jumpers. If it still crackles, it's the amp/relay or speaker switches. Item #1 in the @dankik post will tell you if it's the switch but do switch the speakers off when testing with headphones. I bet @Raccoon1400 is right that it's the diff pair H751/2. Use KSA992 here, better if gain matched with a multimeter with that function.
 
Eventually you will have to solder to replace a bad transistor. Do you have a temperature controlled soldering iron? If not you can damage the board and turn an inexpensive repair into an expensive repair or a non repair-able unit! Do you even know how to solder?
 
Had a 2240 that had the same issue, it was a driver board transistor. Sorry, don't recall which one.

Loud as heck and scared the bejeezus out of me when it would happen.
 
dragnalus said:
I've had my 2270 for over 20 years, and I had it re-capped about 8 years ago. It's worked great until very recently.

The right speaker channel, has a loud crackle that happens at random times. I'm trying to troubleshoot why this is happening, and am hoping folks here can help. Here is what I noticed:


- the crackle happens even when the volume is all the way down.
- the crackle happens regardless of what output is selected (Aux, Phono 1, Phone 2, Tuner, etc.)
- the crackle happens on on the right side channel. When I reverse the right and left the speaker wires, the crackle changes speakers, therefore it isn't the speaker - it's the receiver or the wire.
- the crackle happens regardless of whether the main speaker or remote speaker output is used.

I was thinking of buying some new speaker wire to see if that works. I'm praying it's the wire and not the receiver.

Can anyone shine some light on what they think might be happening?

Also, can anyone recommend some speaker wire that they like for the similar clamps? (I've always hated having to twist the end of a frayed speaker wire and jam it into the clamp thing... )
Click to expand...
Replace all small signal transistors. Every single one.

If one is failing, they all will eventually. Don't waste your time narrowing it down or trying to find the exact culprit, you'll waste hours. Preamp and amp. All of them. It'll cost $10 and time.
 
ivandezande said:
Replace all small signal transistors. Every single one.

If one is failing, they all will eventually. Don't waste your time narrowing it down or trying to find the exact culprit, you'll waste hours. Preamp and amp. All of them. It'll cost $10 and time.
Click to expand...

I keep trying to convince people of this, but again and again I see pics of "fully restored" gear full of old transistors. They'll put bypass caps across the filters, they'll replace ceramic discs and resistors, but the fifty-year-old transistors stay for some reason. Keep fighting the good fight, we'll convince them eventually.
 
I will just add a caveat to the above about transistors:

For a preamp board such as a Marantz 2230/2245/2270 yep go ahead and replace em!

Amp boards for the audio tech sure. For a first timer maybe not, some times you replace transistors on an amp board
and you can run into problems you did not have such as not being able to get the bias down below a certain point.
And I have seen many threads that all transistors were replaced but orientation was not followed for the sub.
Or on others such as Sansui 505, 555 it really can change the bias so be prepared to do extra work.

Power supply- I have seen in the past, if a sub is good on the preamp board, does not mean it will work on a power supply, may be a different function.

I know that @markthefixer on the Pioneer forum is excellent about the rating/functions of transistor subs.
Where the same transistor on a pre amp board and power supply will take a different sub.

Just do not want some beginners diving in and creating problems they did not have.

In fact I really never comment on a sub unless I have used it and has been reliable.
 
patfont said:
I will just add a caveat to the above about transistors:

For a preamp board such as a Marantz 2230/2245/2270 yep go ahead and replace em!

Amp boards for the audio tech sure. For a first timer maybe not, some times you replace transistors on an amp board
and you can run into problems you did not have such as not being able to get the bias down below a certain point.
And I have seen many threads that all transistors were replaced but orientation was not followed for the sub.
Or on others such as Sansui 505, 555 it really can change the bias so be prepared to do extra work.

Power supply- I have seen in the past, if a sub is good on the preamp board, does not mean it will work on a power supply, may be a different function.

I know that @markthefixer on the Pioneer forum is excellent about the rating/functions of transistor subs.
Where the same transistor on a pre amp board and power supply will take a different sub.

Just do not want some beginners diving in and creating problems they did not have.

In fact I really never comment on a sub unless I have used it and has been reliable.
Click to expand...
I agree about the amp board, just the small signal transistors unless you know what you're doing. Power supply is normally safe, bigger is better although I don't like when people use higher speed parts on them.
 
Thanks for everyone's comments.

I removed the preamp to main jumpers, and the crackle is not happening. So it sounds like the source of the problem is likely in the preamp.

I know less than nothing about repairing and/or soldering electronics, so any replacing of transistors will likely mean hiring someone to take a look at it. (I literally don't know the difference between a transistor and capacitor).
 
@dragnalus Good. Sounds like the problem is in the Pre-amp or switches.
A couple more things for you to try to isolate the problem before giving up:
  • Since the volume control has no effect on the crackle, the problem is after the volume control, but before the Main amp
  • First, make sure that your Pre-Out to Main In jumpers are good. Pull them out and replace them with a stereo RCA cable and see if it helps. Also, if you did not clean the jacks, repeatedly insert/remove RCA plugs to try and clean contacts.
  • Next, press the Mono L & Mono R buttons one at a time to see if crackle stops when Mono L is selected (to isolate the issue to Preamp stages or switches)
  • Next, press Low Filt and Hi Filt buttons and check for any difference (if you didn't Deoxit the switches, try pressing it repeatedly many times to try and clean contacts then test)
Report back your findings.
Good Luck :)
 
dankik said:
@dragnalus Good. Sounds like the problem is in the Pre-amp or switches.
A couple more things for you to try to isolate the problem before giving up:
  • Since the volume control has no effect on the crackle, the problem is after the volume control, but before the Main amp
  • First, make sure that your Pre-Out to Main In jumpers are good. Pull them out and replace them with a stereo RCA cable and see if it helps. Also, if you did not clean the jacks, repeatedly insert/remove RCA plugs to try and clean contacts.
  • Next, press the Mono L & Mono R buttons one at a time to see if crackle stops when Mono L is selected (to isolate the issue to Preamp stages or switches)
  • Next, press Low Filt and Hi Filt buttons and check for any difference (if you didn't Deoxit the switches, try pressing it repeatedly many times to try and clean contacts then test)
Report back your findings.
Good Luck :)
Click to expand...

No luck unfortunately. First I cleaned and replaced the existing jumpers, then tested the Mono L&R and Low & Hi Filter buttons - nothing had any affect - the crackle still consistently happens on all settings.

Last ditch, I replaced the jumpers with patch cables, and i *thought* it was actually better for a few hours... Last night I had like 3 hours of listening with only one small crackle. However this morning the patch cables are still in and the crackle is back in full force, so I don't think replacing the jumpers improved anything after all.

It's a bit of an annoying one since the crackle is random... sometimes it happens every few seconds, other times it might go a few minutes or an hour. Circumventing the preamp definitely eliminated it though... Should I consider cleaning the preamp board, or inspecting it for any visible issues?
 
dragnalus said:
tested the Mono L&R and Low & Hi Filter buttons - nothing had any affect
Click to expand...
Good so far, but the purpose of this test was to try to determine the circuit location of the crackle, but you did not report on the details of which speaker the crackle was heard.
  • The test was to press ONLY the L Mono button, then listen. Is the crackle still there? Does it come out of both speakers?
  • Then, un-press the L Mono button, then press the R Mono button and listen for the crackle. Is it still there? Does it come out of both speakers?
  • If pressing these buttons one-at-a-time does not affect the sound of crackle in only the L speaker, then it is being generated after the switches. The way the Mono switches work is to take either the L OR R channel audio and "connect" it to both the L and R channels for amplification. This test was designed to try to locate the part of the Preamp that was causing the crackle.
  • If pressing the buttons, does affect the crackle sound then it is being produced before the Mono switches, if it doesn't then it is being produced after the switches.
I wouldn't spend time cleaning anything until we finish conducting these tests to isolate the part of the circuit that is causing the crackle.
 
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