Problem with seduction after CS4 upgrade

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Shortly after the CS4 upgrade, one of the channels stops producing noise.  This is the front most channel, black.  The other channel works perfectly.  I've isolated the problem to the seduction preamp.  After upgrading to the CS4 board, I had the unit downstairs.  After a while, I took it up to my office.  After this move, I noticed the black channel (left in my setup) was not producing any noise.  I powered down the unit and after wiggling some wires, the channel started working again.  After a few days, it would stop.  Now, I happened to be listening to the preamp at the time it stopped working recently.  There was static and scratching sound coming from the left channel and then audio stopped.  Last thing I did was add some more solder to one of the resistors on CS4 board which weren't soldered very well and I thought that fixed it as unit worked after that.  I had no problems until last night and the left channel was again not working.  The tube lights up when unit is powered on, just no sound.  Is the problem related to the CS4 board?  The right channel works perfectly.

[Grainger49]

I'm assuming the "black" channel (that is the left channel) started producing noise.  Or are you saying that the left channel stopped producing music?  

Since the C4S board was the last change we will look at that first.  How long did it work before the C4S board was added? 

Your description is typical of that of a loose connection (wiggling wires is a good clue here) or a poor solder joint.  First check the interconnects.  Components often take a "bad rap" for the interconnects.  Second I would reseat the tubes.  Remove one, insert, remove, repeat several times.  Maybe 5 or 6 times.  

When the Seduction is not working properly are all the LEDs on the C4S board lighted?

After that is all cleared up you should go back in and resolder (rewet) all the solder joints that are on the left channel of your Seduction.  Try the wiring to and from the board first.  If that doesn't cure the problem rewet the solder joints on the left channel of the board.  

Since the Seduction works well some of the time it is an aggravating but simple problem.  

[[email protected]]

1.  At point of failure, the black/left channel starts producing noise and then completely goes silent, no music or output what-so-ever.

2.  I had the CS4 running about two/three months prior installation of the CS4 board.  I purchased everything at once, just didn't upgrade to CS4 until later.

3.  Interconnects are not the problem as I've tried switching the cables around.  I'll try resetting the tube.  What is the reason for the multiple reseting of the tube?  The tube does glow when unit is powered on.

4.  Yes, all leds are lighted up on the CS4 board when unit is powered.

I'll try resetting the tube after I get home from work and rewet joints if that does not work.  Which ones on the CS4 board are specific to the black/left channel?  Thanks for the help.

[Grainger49]

1.  At point of failure, the black/left channel starts producing noise and then completely goes silent, no music or output what-so-ever.

Ok, that makes sense now.  Noise then failure sounds like something is not making a proper connection.

2.  I had the CS4 running about two/three months prior installation of the CS4 board.  I purchased everything at once, just didn't upgrade to CS4 until later.

Yes, it is better to do it in that order as you get to know what the sound improvement of the C4S is.

3.  Interconnects are not the problem as I've tried switching the cables around.  I'll try resetting the tube.  What is the reason for the multiple resetting of the tube?  The tube does glow when unit is powered on.

The reason to do that is the tube pins can have some oxidation on them.  The tube socket pins may not be making good contact.  Resetting them several times cleans the tube pins assures good contact with the tube socket.  The socket might need "tightening."  But that should be determined later. 

4.  Yes, all LEDs are lighted up on the CS4 board when unit is powered.

I'll try resetting the tube after I get home from work and rewet joints if that does not work.  Which ones on the CS4 board are specific to the black/left channel?  Thanks for the help.

You can see what part of the C4S board is connected to the left channel.  Just check the top and watch where it goes under the top plate.

When the problem happens are all the LEDs lighted?

[[email protected]]

Ok, I reseated the tube five times and still no sound.  Next, I looked at the LEDs.  All LEDs were on on the C4S board, but two looked dimmer that the other two.  With the unit built per instructions, the LEDs are on the right hand side when unit is upside down and C4S board in next to you.  There are two upper LEDs and two lower LEDs.  The bottom left and the top right appear dimmer than the top left and bottom right.  Lastly, I just noticed that the led directly under the tube is not on.  The other led is connected to that tube is on however.  Where specifically should I look for the poor connection?

[Grainger49]

If the LED under the tube is not on, the tube is not on.  The heater may be glowing, but the tube is not conducting.  Measure the voltage at tube socket pins 1 and 8 on both tubes.  Post them as the good tube and bad tube measurements.

Which tube has the LED that is not glowing, the one to the right or to the left when the Seduction is upside down and the circuit board is nearest to you?
 

[[email protected]]

I need a new voltage meter to do this.  I'll try picking up one tomorrow.

The led that is not glowing is on the left, which is the channel not working.

I'll post voltage tomorrow as soon as I get the new meter.

[[email protected]]

Well, I think I got it fixed.  Since you stated it was something to do with power, I followed the large gauge power cable (the one right under the C4S board, right?  The other large gauge cable is for the heater I think.)  I re-soldered the two black wires that go towards the left/black tube on the C4S board and also re-soldered where they connect towards the tubes.  Powered on unit and all LEDs turned on and music started flowing!!!  Does this sound like I fixed the issue or is there a chance I just masked the actual problem temporarily?

[Paul Joppa]

Sounds right to me - you were not getting voltage to the tube from the C4S, now you are.