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Original Message

Changing electrolytics in Audio Research D115

Posted by Bambi B on June 24, 2009 at 17:08:43:

PHOTOS: Top> Audio Research SP10, Below> Back view of Audio Research D115

Mates,

As one of the more technically challenged inmates, I approach any technical task with tube gear with caution.

My trusty Audio Research D115 power amplifier is now 24 years old and has been stored since 2001. I moved a couple of weeks ago and am reviving my main tube system: Oracle Delphi III/SME V /McIntosh MR67 > Audio Research SP10 > ARC D115 > Vandersteen 2C- I thought to change the original 5 large electrolytic capacitors- 4 tall and one short.

These are the big blue ones in the photo above and a known Mallory item: [Mouser Pt/ CGS801T450V4]. If I do this, the parts are about $40 each from Mouser instead of $75 from ARC- plus labour plus saving the wear and tear of sending an amplifier that in the box is 70 lbs twice 1600 miles.

The connection is by screw terminals- no soldering.

D115 Questions:

1. Is there any special treatment to the connectors- use or avoid contact enhancer?, cleaning of the terminals?

2. I'm assuming this long-stored amp with new capacitors should be brought up on a variac. Suggested procedure?

3. Should there be a forming/ burning-in/ stabilizing period before use?

4. Is trying this myself a false economy and there is likely coupling caps and other parts that should be tested and possibly replaced?

SP10 Questions:

I'm really, really looking forward to getting the SP10 and D115 back in use. It needs a new gain pot and I'm debating trying that one,..

1. The gain pot on the Audio Research SP10 is as far as I know a "double" ALPS- the left front component in the photo top- which does look like a double box. This pot the last time I tried it- 2005- makes a terrific scratchy- boomy noise when moved. Is it possible to clean this pot to improve it or is replacement called for?

2. How fussy or danger of damage is involved to replace this? I don;t know how it is attached, but think it may have leads through traces on the board.

Many thanks. Sorry to bother you with elementary stuff.

Cheers,

Bambi B