I have an strange issue that just appeared on my Rotel RA-2030.
The volume control has just developed a flat spot between about 40 and 50%. There is absolutely no static or other issues, the volume just stops increasing in this range and both channels are affected equally.
I’ve cleaned and metered the pot and the resistance is linear all the way through a full sweep.
Next step will obviously be start pulling and testing components but I’ve never heard of this before and wondered if anyone else had.
The volume control has just developed a flat spot between about 40 and 50%. There is absolutely no static or other issues, the volume just stops increasing in this range and both channels are affected equally.
I’ve cleaned and metered the pot and the resistance is linear all the way through a full sweep.
Next step will obviously be start pulling and testing components but I’ve never heard of this before and wondered if anyone else had.
The manual I have for the 2030 shows the volume control as a weird 4 gang arrangement.
I'm going to suggest...... that you've picked up on something it probably has always done.
Does the loudness control affect this?
The first test to prove or otherwise is simply to monitor the output on a scope etc and see how the actual output of the amp varies with the control.
Ultimately it's all just a resistive network and so both channels having an issue is off the scale probability wise but I'd counter that and say that something 'physical' such as a broken ground etc that is common to both might do something unexpected... but that's clutching at straws.
I'm going to suggest...... that you've picked up on something it probably has always done.
Does the loudness control affect this?
The first test to prove or otherwise is simply to monitor the output on a scope etc and see how the actual output of the amp varies with the control.
Ultimately it's all just a resistive network and so both channels having an issue is off the scale probability wise but I'd counter that and say that something 'physical' such as a broken ground etc that is common to both might do something unexpected... but that's clutching at straws.
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Yes, I also couldn’t see how both channels could be affected equally, nothing is common apart from the power supply and grounds. I did not try with the loudness in, this is a very high volume level.
I have a moderate level of experience and hoped someone more experienced has at least heard of this symptom. I can’t say for sure it never did this in the past but it’s fairly noticeable but is at quite a high volume however so it’s possible.
Even if it did always do this, I still can’t see how it’s possible. I will put a signal generator on and see where I can and cannot see the flat spot happening and hopefully pinpoint the cause.
I have a moderate level of experience and hoped someone more experienced has at least heard of this symptom. I can’t say for sure it never did this in the past but it’s fairly noticeable but is at quite a high volume however so it’s possible.
Even if it did always do this, I still can’t see how it’s possible. I will put a signal generator on and see where I can and cannot see the flat spot happening and hopefully pinpoint the cause.
Sure sounds like the pot's loudness taps are disconnected from their related circuits.
Set the pot to around 1/2 rotation and check the resistance from the wiper to ground
as you switch the loudness on and off. If the reading does not change significantly,
the loudness taps are somehow not connected.
Set the pot to around 1/2 rotation and check the resistance from the wiper to ground
as you switch the loudness on and off. If the reading does not change significantly,
the loudness taps are somehow not connected.
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I will definitely check tonight when I get some time in the shop. The loudness button does work at low volumes so I didn’t think to even look at that circuit however now that you pointed it out, a problem in that circuit could impact the volume level.
Thanks for the tip.
Thanks for the tip.
And will cause a flat spot if no connection to the loudness tap.
Probably it's not the problem, but it sure sounds like it could be.
Do first use a generator to verify the electrical presence of the flat spot.
But, maybe it's always been there (due to the placement of the loudness tap terminal),
and you just noticed it. That's about where the loudness tap is usually located.
Probably it's not the problem, but it sure sounds like it could be.
Do first use a generator to verify the electrical presence of the flat spot.
But, maybe it's always been there (due to the placement of the loudness tap terminal),
and you just noticed it. That's about where the loudness tap is usually located.
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Not much to update, I am guessing I just never noticed this before since it is at such a high volume level.
I probed various points in the audio circuit and it appears the flat spot originates on the volume control board even though the potentiometer is linear. Makes no difference if the loudness is in or out and as I said earlier it is exactly the same on left and right channels. Clearly this is inherent to the circuit but it still amazes me in never noticed in the couple years I’ve had this unit.
Thanks for the suggestions though, I certainly never thought to check the loudness circuit until the obvious was pointed out to me.
I probed various points in the audio circuit and it appears the flat spot originates on the volume control board even though the potentiometer is linear. Makes no difference if the loudness is in or out and as I said earlier it is exactly the same on left and right channels. Clearly this is inherent to the circuit but it still amazes me in never noticed in the couple years I’ve had this unit.
Thanks for the suggestions though, I certainly never thought to check the loudness circuit until the obvious was pointed out to me.