"Mushy" Marantz 2220B Input Selector

[ringading]

I searched the forums for this problem but didn't find anything too specific. I have a 2220B that I have recapped and balanced and it sounds fantastic. The only problem is the input selector is mushy and you need to fiddle with it to get it set on your input to make sure you get both channels. I have noticed this issue with lots of receivers, some have a crisp click when changing inputs and others are not as solid.

Is this just a function of age? I suspect the mechanism with the ball bearing is just worn out and the switch may need to replaced the fully fix the issue. Just wanted to check if there were any other potential solution. I have cleaned the switch with contact cleaner and deoxit with no improvement.

Thanks all!

 

[woodj]

Did you try cleaning it?

 

[ringading]

As noted, I have cleaned it liberally with contact cleaner and deoxit. Not sure if corrosion would cause the issue - I can see it causing some dropout but it seems to be mechanically worn out perhaps.

 

[catrafter]

Maybe the detent 'ball' or spring is missing from the selector switch. Some switches even have two.

Tom

 

[62vauxhall]

This might not be the same symptom you're experiencing, but FWIW, I cleaned the rotary input selector on an APT Holman pre-amp. Afterwards, it worked but was very stiff to turn. It did not have that "positive click stop" feel as it had before. I tried Fader Lube and D5 but it did not really help with the stiffness.

I happened to visit a local electronics repair shop on another matter but asked the tech what he'd do with such a control. He advised that he did in fact use a lubricant called Free Flow, sold in auto supply stores for this exact issue. Not on the electrical contacts but on what amounts to the shaft's "bearing".

I got some to try. It did make an improvement and continues to do so over time, the more the control gets used.

 

[Goldie99]

Sounds like it's time to open the switch and take a look.... not sure what construction it is, but it sounds as if the contacts are no longer making good contact (loss of spring tension ? physical wear and tear ? years of built up crud ? etc.), you may or may not be able to 'tweak' them to increase contact pressure, but at least the real problem should be apparent.

 

[dshoaf]

How about a better definition of 'mushy'? I'm suspecting a mechanical problem where the switch itself is attached to the faceplate. If the nut is loosened, then the switch would rotate a bit before the detent system kicks in. This would account for one form of mushiness.

Cheers,

David

 

[ringading]

Thanks for all of the suggestions.

It is attached to the face plate solidly. I imagine it is either the ball bearing mechanism or the contacts. Just not sure which one helps to make it "click" into position and stay there. It rotates more like a volume knob with a little resistance between inputs. I will see if there are springs missing. Like I said, I have had units with precise input selectors where they just click into place and some where the "click" is not so precise. This is just the least solid I have ever had so I imagine it might just be a case of wear and tear over 50+ years.

I may be able to replace it from a donor unit. Its a different model so I will need to check if the part #s are the same. Not a fun job and the unit works fine, just wish I wouldn't have to fiddle with the input knob to get good clear sound from both channels.

 

[Goldie99]

The only picture I could find on the net suggests it's an open frame type switch (?), if so, you may be able to 'inspect' it sufficiently without disconnecting any wiring, e.g. using an illuminated magnifying type lamp. You might need to remove if from the front fascia for a good look, but that should be simple compared to the pita that re-wiring or replacing it looks to be.