Is this what's causing the hum in my Dared SL2000a?

audiocr381ve

Not being able to bear the fact that my Dared SL2000a is on the sidelines because of a pretty bad hum, I popped the hood and found this.



What the hell? Random loose wire connected to god knows what. If you can't tell by the picture, it's the red wire that is connected to a PCB but the other end is not connected to anything. I'm guessing this unit was modded at some point but I have no clue what I'm looking at.

Can anyone with a SL2000a pop their hood to see where it goes for me?

heiney9

Here are some photo's I took awhile ago, may or may not help.

FTGV

Can you post a pic showing the connection point of the other end of the wire?i

audiocr381ve

Thanks Brock. From your pictures, you DEFINITELY DO NOT have a loose red wire that's just dangling unconnected.

Here ya go FTGV:



I can take even higher resolution pictures. I wish I would have taken my macro lens home from the office, I hope that cropped image helps identify what the red wires function is.

FTGV

Ok can't see clearly exactly the same connection point in Brock's pic's.The little vertical board it's connected to is unfortunately not shown in the schematic so not sure of it's function ,but it is soldered to the remote control decoder IC pc board.

audiocr381ve

FTGV wrote: »

Ok can't see clearly exactly the same connection point in Brock's pic's.The little vertical board it's connected to is unfortunately not shown in the schematic so not sure of it's function ,but it is soldered to the remote control decoder IC pc board.

Hmm, that might explain why my remote does not function correctly. Very strange. I really appreciate you taking a look at the schematic Fred (I think I remember your real name being Fred?).

george daniel

hope this helps.

FTGV

Indeed it does George,Thanks.From the looks of the coiled yellow wire connected to the little PC board it appears to me like an antenna for recieving the RF signal from the remote.The red one in the op's is just not nicely coiled up.

FTGV

audiocr381ve wrote: »

I really appreciate you taking a look at the schematic Fred (I think I remember your real name being Fred?).

Yes it's Fred,and the schem was still close at hand since Brock kindly sent it to me very recently.However it only shows the basic gain stage and power supply,not the peripherals like the remote control section etc.

heiney9

Hmmmm interesting Fred, mine doesn't have that. Atleast that I can see in my photo's.

H9

FTGV

It might just be tucked underneath the board Brock.

audiocr381ve

Ahh so it's not supposed to be connected to anything on the other end?

FTGV

audiocr381ve wrote: »

Ahh so it's not supposed to be connected to anything on the other end?

Correct.Since the remote is RF not infared it has an antenna instead of an IR sensor. You might try to coil it up similar to the one in Goerges pic.You could use a pen or pencil as a temporary former to wrap the wire around to neatin it up.What was the issue with the remote you were having?Was it purchased new or used?

george daniel

Damn,, you are good Fred

audiocr381ve

george daniel wrote: »

Damn,, you are good Fred

I agree, thanks for digging in and helping me out on this.

The Dared was bought from a fellow Polkie. The remote only turns the volume down, I cannot turn the volume up, so it's absolutely useless. I bought new batteries and it still didn't function right.

The hum issue is still strange. I swapped in new speakers (Magnepan MG10's) and the hum was not as noticeable as it was with my Monitor 5's, but it's still there.

George, how's your Dared sounding with the cap upgrade? Was their anything else you did to it?

FTGV

audiocr381ve wrote: »

thanks for digging in and helping me out on this.

Your welcome.

The hum issue is still strange. I swapped in new speakers (Magnepan MG10's) and the hum was not as noticeable as it was with my Monitor 5's, but it's still there.

It may be less noticable on Maggies since they are likely several db lower in sensitivity than the 5's.As for the hummmm it appears the circuit ground is tied to chassis ground (thus the safety ground) which can cause ground loop issues in some set ups.But IIRC you have already tried the standard experiments for identifying a ground loop ?Cheater plug,disconnecting sources etc.

audiocr381ve

FTGV wrote: »

Your welcome.

It may be less noticable on Maggies since they are likely several db lower in sensitivity than the 5's.As for the hummmm it appears the circuit ground is tied to chassis ground (thus the safety ground) which can cause ground loop issues in some set ups.But IIRC you have already tried the standard experiments for identifying a ground loop ?Cheater plug,disconnecting sources etc.

Correct, I tried the cheater plug and that didn't work. Swapped in another pre and the system is dead quiet.

audiocr381ve

FWIW, I have a subwoofer connected to the loop output jacks on my Parasound amp, and the hum gets through to the subwoofer when using the Dared.

george daniel

Mine is still quiet as a mouse,,,I upgraded the a total of 6 caps in mine IIRC,,the Obligatto's (2) and 4 Russian teflon's (output),,I've since replaced the signal tubes with some Mullard's that F-1 suggested to someone in another thread,,I am very pleased with the sound.I wish I knew how to help you eliminate the hum,,one question/suggestion--- can you try the Dared in another system and someone else's home/rig? My brother has the same issue with a Dodd ELP,,,it does not hum in my system,,I think it may be in his home wiring,,just a thought--good luck.

Boomzilla

My brand new Dared SL2000a HUMS also. Has ANYONE found a cure? Is there even such a thing as warranty?

Thanks - Boomzilla

lanchile

Try putting all wires that carry AC voltages and put them as far from the input as possible and twist them, also put those wires carring AC as close to the metal chassis as possible. Those wires look like a plate of "spaguetti" lol.

PS: Check for GROUND LOOPS!!!

audiocr381ve

lanchile wrote: »

Try putting all wires that carry AC voltages and put them as far from the input as possible and twist them, also put those wires carring AC as close to the metal chassis as possible. Those wires look like a plate of "spaguetti" lol.

PS: Check for GROUND LOOPS!!!

How do you find ground loops? I mean, I've googled it but haven't found anything all that helpful.

Boomzilla

Ground loops occur, as I understand it, when one component is at a different ground voltage than another. In theory, all components should be "commonly" grounded so that there is no potential for offset voltage. In practice, however, components are often plugged into different circuits of the home, which can allow the condition to exist.

Additionally, some AC supplies can have offset at their crossover point. In other words, the point where the positive voltage swing of the sine wave hands off to the negative is not exactly at ground voltage.

Some ways to omit ground loops:

1. Ground (with the three-prong AC cord) one and only one component. All others should have only two-prong connections. If necessary, cut off the ground prong of the AC cords on all but one component.

2. Use a voltage conditioner that removes DC offset from the incoming AC voltage.

If neither of these work, then the hum is due to issues inside the components themselves. This is most often from sloppy wire routing. The AC input wires should be as far away as possible from the audio signal wires. The AC input wires should further be twisted around each other.

I'm sure that there are some electrical engineers on this forum who will be so kind as to correct any of my misconceptions?

Thanks - Boomzilla

Sprags

Try connecting a wire from the amp to the preamp. I had a ground loop issue because of the wiring in my condo. A tech from Parts Express suggested that and it solved the problem. Attach

audiocr381ve

Sprags wrote: »

Try connecting a wire from the amp to the preamp. I had a ground loop issue because of the wiring in my condo. A tech from Parts Express suggested that and it solved the problem. Attach