Balance control on stereo amplifier does not work. Adjusting the volume changes the balance.

[FaultyVibes]

I recently bought a second-hand Mitsubishi DA-U530 integrated stereo amplifier with a broken balance control. Adjusting the balance to the left produces crackling sounds in the right channel but does not change the output power of either channel (as indicated on the amplifier), except for it cutting out at some positions of the dial and when the dial is completely turned to the left. The same goes for adjusting the balance to the right but for the left channel.

Adjusting the volume on the amplifier changes the balance, with higher volume shifting less power to the left channel and more power to the right channel. The power outputs are equal at about 5/10 on the volume control. Changing the volume of the input signal does not affect the balance.

I've gotten the suggestion that the broken balance is likely due to a bad connection in the balance potentiometer. However, I cannot reason how adjusting the master volume could influence the balance if this was the sole issue. But that might be a lack in my understanding.

Is this indeed just the potentiometer, or are there likely other issues at play?

Kind regards and many thanks,
FaultyVibes

 

[swechsler]

Classic dirty controls. Get yourself a can of Deoxit D5 and read this thread.

 

[FaultyVibes]

Classic dirty controls. Get yourself a can of Deoxit D5 and read this thread.

Cool, I'll try that. Thanks!

 

[kwayde]

I recently bought a second-hand Mitsubishi DA-U530 integrated stereo amplifier with a broken balance control. Adjusting the balance to the left produces crackling sounds in the right channel but does not change the output power of either channel (as indicated on the amplifier), except for it cutting out at some positions of the dial and when the dial is completely turned to the left. The same goes for adjusting the balance to the right but for the left channel.

Adjusting the volume on the amplifier changes the balance, with higher volume shifting less power to the left channel and more power to the right channel. The power outputs are equal at about 5/10 on the volume control. Changing the volume of the input signal does not affect the balance.

I've gotten the suggestion that the broken balance is likely due to a bad connection in the balance potentiometer. However, I cannot reason how adjusting the master volume could influence the balance if this was the sole issue. But that might be a lack in my understanding.

Is this indeed just the potentiometer, or are there likely other issues at play?

Kind regards and many thanks,
FaultyVibes

I had something act odd like that in the past but can't remember what model it was. The balance control was acting like a volume control for one channel or something like that.
Turns out the volume pot had cold solder joints.

On the circuit board I reflowed the solder for both the volume pot and balance pot which got it working correctly again.

Check the circuit board connections on yours to see if any of them are bad. Cold solder joints look normal except they have small rings on them that are breaks in the connections. Seed the following pic to see what I mean.

 

[FaultyVibes]

I had something act odd like that in the past but can't remember what model it was. The balance control was acting like a volume control for one channel or something like that.
Turns out the volume pot had cold solder joints.

On the circuit board I reflowed the solder for both the volume pot and balance pot which got it working correctly again.

Check the circuit board connections on yours to see if any of them are bad. Cold solder joints look normal except they have small rings on them that are breaks in the connections. Seed the following pic to see what I mean.

View attachment 3430314

I'll make sure to check the solder joints. Thanks a lot!

 

[tarior]

Use DN5 for pots, not D5.

 

[swechsler]

Use DN5 for pots, not D5.

Actually a thread linked to the thread I posted earlier recommends D100. I think most of us have use D5 on pots without issue, but your caution is not unwarranted.

 

[tarior]

Actually a thread linked to the thread I posted earlier recommends D100. I think most of us have use D5 on pots without issue, but your caution is not unwarranted.

D100 is fine, IME, but I like the flushing action of the 5% to help wash the dust out. I always recommend the DN5 as it's in the CAIG literature that it is more suitable for pots, while D5 is more suitable for switches. My experience with the two seems to bear out CAIG's recommendations.
It never fails to surprise me how many techs, and hobbyists alike, are completely unaware of the existence of DN5.