[Lawler Bb]

I've got a question for the Van Alstine gurus:

I have a Super Pas 4i preamp.  I am having some problems with either channel cutting in and out, sometimes with static and other times without.  I have located the problem to the Stereo/Mono switch and the Input/Tape swtich.  I can get the signal to come back to normal in both channels after either toggling both switches many times or in worse instances, rocking/wiggling the swtiches around in respect to the front aluminum plate of the preamp.  This is to not say that my swtiches are loose and flopping around, they aren't, but there is a tiny bit of wiggle room for each one.  

Now, it seems to me that either the swtiches are shorting out, or I have a loose wiring problem.  I have looked inside and all wiring to and from the switches looks good and properly soldered.  I'm not sure what the problem could be.  Any ideas??

Also, my volume pot is a bit scratchy when rotating it.  I wouldn't mind replacing it with something equal or better.  Can someone tell me what I have so I can go about finding a replacement?

I am the second owner of this preamp, and it was a kit when it was bought years ago by the first owner.  I have had this preamp for at least 5 years and it has worked wonderfully until now.  I hope to get things back to normal, as I really enjoy how it has worked in my system.

Thanks in advance.

[Keith F.]

Hi Lawler,

I also have a pas 4i and those switches after time cause the signal to cut out or sound scratchy. What I've found handy to clean them is a product called Caig Deoxit. It comes in several types of dispensers. The one I use is the liquid in a small bottle that is dispensed by a tiny metal 'pin' so You can get into small places. It is not the spray type but is the undiluted liquid. Tip the preamp up so the front panel faces up and put in a small amount in the 'crack' between the switch body and the 'rocker' of the switch then flip the switch several times. It may take a while for the cleaner to work on the contacts to de-oxidize them.

It is possible that this will not completely fix them as it has happened once before with mine. I did replace the input and tape switches once before.

AVA is great to deal with if You need to send in Your unit. There phone # is: 651-330-9871.

Hope this helps.

Keith

[avahifi]

We are aware of an issue dealing with the original rocker switches in our SL series preamps.  The switches were the best we could find at the time, and were designed to be self cleaning when used, but unfortunately, in some cases these switches are never used.  This can lead to oxide build up and signal dropout.

This issue was resolved about a year ago in new production units.  The faceplate was changed to accept a finally available gold contact logic level switch that can never oxidize and drop out.

There are several solutions to the dropout issue in older units.

First, use the switches, cycle them back and forth a few times each week even if you normally do not use their functions.  That will keep them clean.

Second, if dropout has occured, cycle each switch about 50 times with the unit turned off.  Using Caig Labs Deoxit cleaner as mentioned above is very helpful.

Third, if your unit is out of warranty, we will supply you free replacement original switches if you want to make the the replacements yourself.

Fourth, if your unit is in warranty, we will of course replace the switches in kind here at no charge.

Finally, the set of three new gold contact switches are available for $115 factory installed only.  They are expensive switches, and the labor time for installation in an original faceplate is considerable.  The original switch wiring has to be redone.  This revison is being offered at our cost only, not as a free upgrade.

We hope one of these solutions will resolve your concerns.

Frank Van Alstine

[Lawler Bb]

Thank you for your responses.  I'll go get a bottle of Deoxit and see if that knocks it out.  

I am almost positive my unit is out of warranty, it is several years old (I would estimate 7 or 8 years) and I am the second owner.  Frank, I appreciate your offer on the swtiches, I will decide on something and be in contact soon.  

Now, does anyone have infomation on the volume pot in the Super Pas 4i?

Thanks again.

[avahifi]

The Noble stepped precision volume and balance controls used have proved to be very reliable and long term noise free.  They are perfectly matched (laser trimmed multiple discrete resistors inside) and have a "broom" like multiple contact wiper for long term low noise operation.  The only flaw we have experienced is failure of the "click stop" mechinism due to an assembly error at the factory.  This caused some units to loose their click stop feel after several years of operation.  We have subsequenty fixed that problem in house and fix any failures free of charge here.

Noise in the control is very unusual.  Likely a shot of Deoxit in the slot by the connection lugs will quiet it permanently.  The only other possiblity is a leaking capacitor in the audio circuit itself putting low level DC on the control.  Note that some noise will be present in the first few minutes of operation after cold turnon until the circuit capacitors form on solidly.

Frank Van Alstine

[Lawler Bb]

Frank,

I am not sure that I understand your reply about the volume control.  There are supposed to be individual steps you feel when you rotate it?  Mine is smooth, and I have never felt steps since owning the preamp.  Come to think of it, my balance control is smooth too.  

Having said that, the noise happens nearly every time I rotate it, whether I have just turned it on (and I usually wait 10 minutes or so) or if I have left it on for a day or two.  

I appreciate your help and feedback.

[avahifi]

Since you are not the original owner of this unit, we cannot be sure it is in original condition.  The noise might be caused by circuit modifications done after the unit left here.  People do install goofy "audiophile" grade parts in the strangest places, screwing up things a whole lot.

However, it does appear that the click stops have failed in your preamp, and as we said above, this is a free repair if you want to return the unit to us (use insured UPS and pack so it will survive being kicked down a flight of stairs).  Include a check for $15 for return shipping.  We will address the control noise issue too, but that won't necessarily be free.

Note that our shipping address is 2665 Brittany Lane, Woodbury, MN 55125, not the Burnsville address shown on the back panel label.

Frank Van Alstine