2226B Balance Knob Issues

[Houjuu]

Hey everyone, I've had the pleasure of owning a low-hours 2226B receiver for about a year now, and almost everything about it is perfect aside from the single issue of having an imbalanced balance knob. When centered, the left channel is far more powerful than the right, but if I move the notch to exactly 3 o'clock, it evens out, though at a lower volume than if it were balanced correctly. I've tested this on multiple pairs of speakers, multiple pairs of headphones, through every input source on the receiver, and in mono mode. Everything still gives the same imbalanced result.

I have opened the receiver up and thoroughly cleaned it twice with contact cleaner as well as applying lubrication on the pots, though the issue persists. I have not, though, actually disassembled anything electronic to get to the innards of any of the pots, but I really stuck the nozzle of the cleaner way into the slits of the pots anyways. No caps visibly look burst either, though I obviously won't rule out an electrical issue.

An odd thing to note, for about an 8 hour period on some random night, the balance knob worked again? This was such a spontaneous event and it happened late at night so I didn't get to do any thorough tests, but it just balanced itself properly out of nowhere. The next morning, it was back to being partial to the left channel. I thought this could be a speaker relay issue, but another post on this site says the 2226B does not have a speaker relay, so I am really unsure about how this happened at all.

Alas, the knob is still imbalanced and quieter than if it were balanced. I am at a loss at what to do next other than a complete recap, though for an issue as small as this, hopefully only a few caps need to be replaced? Though which ones, I am unsure about. Any help would be greatly appreciated, thank you all!

 

[AE Bob]

I have seen an issue on many of the smaller Marantz receivers where they come into the shop with the complaint of one channel weak. In MANY cases the issue is not a weak channel, but one that is actually too loud. It is caused by an open electrolytic capacitor in the negative feedback network of one of the main amplifiers. This is evident if the loud channel gets really loud in FM, before the volume is past 1/2 (12:00).

 

[kwayde]

Since it did work after a while try probing circuit boards, etc. with a non-conductive rod to see if you can get it to work/not work. Push on the boards a bit to get them to flex/move. Probe wiring and harnesses, etc.

Looking to see if there's a bad connection someplace.

 

[Houjuu]

I have seen an issue on many of the smaller Marantz receivers where they come into the shop with the complaint of one channel weak. In MANY cases the issue is not a weak channel, but one that is actually too loud. It is caused by an open electrolytic capacitor in the negative feedback network of one of the main amplifiers. This is evident if the loud channel gets really loud in FM, before the volume is past 1/2 (12:00).

This may very well be the issue. The FM signal is unbearably loud, even at barely past 6 o’clock on the volume knob; I wouldn’t dare turn it past 7. When the knob is turned ever so slightly to the left, the FM signal is very quiet, but it is in fact balanced. A single millimeter more and it becomes painfully loud. So you are saying somewhere in the amplifier path there is a bad cap? I’m a novice at reading schematics; but I’ll attempt to locate the open cap to the best of my abilities.

Since it did work after a while try probing circuit boards, etc. with a non-conductive rod to see if you can get it to work/not work. Push on the boards a bit to get them to flex/move. Probe wiring and harnesses, etc.

Looking to see if there's a bad connection someplace.

I’ll try this first before any electrical work, just to see if any wires are caught anywhere to stop future issues.

Thank you both so far!

 

[morgan]

Sounds as though your knobs may not be installed correctly, where maximum travel is marked by dots on the faceplate. Six o'clock on the volume control is unattainable with correct orientation of the knob.

 

[Houjuu]

Sounds as though your knobs may not be installed correctly, where maximum travel is marked by dots on the faceplate. Six o'clock on the volume control is unattainable with correct orientation of the knob.

That was my mistake, I was incorrectly visualizing the receiver's knobs. Lowest position is 7 o'clock, so I should have said that once barely past 7, the FM signal is quiet but balanced, but any movement after that it becomes overly loud and unbalanced. 9 o'clock is where I usually keep the knob, but for an FM signal, it would be terrible to try.

 

[dankik]

You can try to isolate the problem to the Pre-amp or Main Amp by using a stereo RCA cable to cross-connect the L Pre-out to R Main In, and R Pre-out to L Main In. Do this and see if the problem remains the same or switches sides. Install the cable with power off, then turn on to test. If the problem stays the same, then then there is a problem with the Main Amp, if it switches sides then it is a problem in the Pre-amp.

 

[Houjuu]

You can try to isolate the problem to the Pre-amp or Main Amp by using a stereo RCA cable to cross-connect the L Pre-out to R Main In, and R Pre-out to L Main In. Do this and see if the problem remains the same or switches sides. Install the cable with power off, then turn on to test. If the problem stays the same, then then there is a problem with the Main Amp, if it switches sides then it is a problem in the Pre-amp.

Tried this and luckily the same results occurred with the left channel being more powerful than the right. Good to know for sure though that the issue is with the main amp. That being said, I believe I may have found the bad cap, though I am a beginner in understanding circuitry and am really only basing this off the slightest malformations I can find just by viewing the caps.

AE Bob said that the issue would lie within the negative feedback circuit. I am not sure where this is within the diagram, but I will send some images of where I think the bad cap is. I can send more images of the circuit board if needed. If nothing more, this is great practice in understanding basic electrical engineering and schematic reading!

The cap labeled C706 is the only one that I can see any semblance of visible decay on, though C705 could possibly have some as well, however not as prominent as on the former. Of course, a cap may look fine and not be functioning, so this is only to rule out the visibly odd ones. Again, I am only beginning to understand circuitry, so this may not even be the right place.

 

[dankik]

An odd thing to note, for about an 8 hour period on some random night, the balance knob worked again? This was such a spontaneous event and it happened late at night so I didn't get to do any thorough tests, but it just balanced itself properly out of nowhere. The next morning, it was back to being partial to the left channel.

So, can you tell me if the L channel got louder or did the R channel get quieter compared to when it briefly worked again?

...thoroughly cleaned it twice with contact cleaner as well as applying lubrication on the pots,

Also, did you clean these speaker switches (S701) on the board with Deoxit and thoroughly work them in/out? If not, try that first.
One more thing, did you try both the System 1 and System 2 speaker outputs, or only System 1? If you did not try the other, with power off, connect your speakers to the System 2 terminals.
___

 

[Houjuu]

So, can you tell me if the L channel got louder or did the R channel get quieter compared to when it briefly worked again?

I am rather certain that the left channel did indeed get quieter, and since I had the balance knob turned to 3 o'clock to get even sound, the right channel was expectedly louder; this is what initially caught me off guard. I assume this now means the issue is most definitely with some electrolytic cap on the main amp board.

Also, did you clean these speaker switches (S701) on the board with Deoxit and thoroughly work them in/out? If not, try that first.
One more thing, did you try both the System 1 and System 2 speaker outputs, or only System 1? If you did not try the other, with power off, connect your speakers to the System 2 terminals.

I did do this, yes. I cleaned them again just a few hours ago and tested both speaker inputs, just to see if this would alter anything. Sadly it did not.

 

[dankik]

I am rather certain that the left channel did indeed get quieter, and since I had the balance knob turned to 3 o'clock to get even sound, the right channel was expectedly louder;

When centered, the left channel is far more powerful than the right,

Now I am confused. OK, so what you now say is that with the balance control centered, the left channel sounds quieter than normal (and the right channel), whereas before you stated that the left channel "is far more powerful"?

 

[Houjuu]

My apologies, it is late here and I need to get to bed. To remedy the issue (to lower the overpowered left channel), I turn the knob to 3. The one time the issue seemingly fixed itself, and since the knob had been previously set to 3 (270°), the left channel became quieter, and when the knob was centered, all was balanced.

I was saying that since I usually set the knob to 3, the right channel was louder, which is the expected function when the balance is working.

Definitely confusing myself as well, sorry about that. All in all, when the knob fixed itself for that brief period, both channels were equal when centered. When it returned to not working properly, left got louder when centered.

 

[dankik]

When it returned to not working properly, left got louder when centered.

Sorry to ask so many questions but it is important to understand. When it was NOT working, and with the balance control centered, the Right channel remained at the correct normal volume, but the Left channel got louder than normal? Correct?

The other option is that with the balance centered, the Right channel got softer and the Left channel remained at the same volume.

What I'm trying to determine is in the Left channel getting louder than normal, (as @AE Bob states), or is the Right channel getting softer than normal.

 

[Houjuu]

What I'm trying to determine is in the Left channel getting louder than normal, (as @AE Bob states), or is the Right channel getting softer than normal.

I am inclined to think that when the balance knob was not working as intended and it was centered, left was louder than normal and right was normal. I say this because the 2226B is 30wpc and the volume I had it at (barely past 7 o’clock) seemed far too loud for that small of an adjustment. Right seems totally ok volume-wise.

 

[dankik]

The cap labeled C706 is the only one that I can see any semblance of visible decay on, though C705 could possibly have some as well,

Do you have a DMM that can measure capacitance?
With power off, measure the capacitance and compare it to the capacitor on the other channel.

 

[kmagnuss]

I had a somewhat similar situation with my 2230 where the balance was almost always louder on the right side, but sometimes it would be even.
Tried a ton of different things until I noticed vibrations on the right amp board would cause fluctuations... then tracked it down to one of the transistors that had a star shaped heat sink on it. I never had the high FM volume like you, and of course it's a different receiver, so it's most likely different but man I replaced darn near every darn cap and pot on the thing before getting it figured out.
Keep plugging away at it... you'll get it figured out eventually.

 

[Houjuu]

Do you have a DMM that can measure capacitance?
With power off, measure the capacitance and compare it to the capacitor on the other channel.

Yes, I’ll be testing caps soon once I have time to desolder and troubleshoot. I don’t have a dedicated ESR meter, but just getting a basic idea of if an electrolytic is functioning or not will be good to know.

 

[Houjuu]

I replaced darn near every darn cap and pot on the thing before getting it figured out.

Oh man I really hope I won’t have to trial and error everything lol, awesome that you got yours working through all that effort.

 

[Houjuu]

Okay update! I have replaced caps C706 and C705 on the power supply and main amp board. Testing these two caps with a DMM showed that they functioned as normal, but I replaced them anyways to get some soldering practice in. Once powered on, the exact same issue persists: left channel is much stronger than right when balance is centered and FM is unbearably loud at even the lowest of levels. From here, since I know how to test components better now, I'll go about checking to see if everything is reading as it should. I still hope that the issue lies within the power and main amp board, so what other caps/components would be good to check here? I trust in AE Bob saying that it lies somewhere in a negative feedback circuit.

Another question: if my attempts prove to be futile, is there any harm in just keeping the amp balanced to the right like I have been doing? I am aware I have to crank the volume higher than I would have to if the balance was working, but are there any long-term ailments that could arise from this? I don't personally think so, but better safe than sorry.

To show which caps I replaced:

 

[AE Bob]

First, just to be positive the issue is in the main amplifier circuit, and not in the preamp / tone circuit, use a stereo patch cord to jump left to right and right to left in the preamp / main amp jacks on the back (I did not see in the previous posts where this was done). I the loud channel stays the same, it is obviously an issue with the main amp. If it goes to the other channel it is in the preamp or tone circuitry.