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View Full Version : My BGW 103 Preamp Build...



Loud & Clear
11-07-2008, 12:08 PM
Let's see where do I start. I have several different units I am working on. It's tough to remember everything.

Well, I replaced all the carbon film, and carbon composition resistors with 1% presision metal film resisters. Then I moved on to the electrolytics. I replace those with Panasonic FC series caps. I used a little higher voltage than were the units I replaced. Then I replaced a bunch of tantalums w/electolytics FC again. changed out the metalized mylars, and mylar films with 1% metalized polypropylene units. I disassembled and cleaned/lubbed the stepped attenuator volume control, and the stepped balance control. I changed out the pitted oxidized rca jacks. There was alot of presision drilling and soldering to do on the rca jack replacement. I changed out the dull red 1970's era L.E.D.'s. I desoldered, then resoldered every connection on the parts I did not replace. I maticulaously defluxed the solder joint side of the the pc board, to keep any reaction between components at a bare minimum. There's more, I'll just post some pictures of the unit. http://www.audiokarma.org/forums/images/smilies/biggrin.gif, you will notice I have all the resistor color codes aiming the same direction. I tried to do that with the caps where possible. I have a tad of OCD... http://www.audiokarma.org/forums/images/smilies/wink.gif

The unit sounds Great. Very dynamic, and clean...

http://img207.imageshack.us/img207/4605/1preboardfullbefore1im3.jpg


http://img216.imageshack.us/img216/2037/02preboardfullbefore2cw1.jpg


http://img207.imageshack.us/img207/8866/03preboardbasstreblesecpm6.jpg


http://img219.imageshack.us/img219/7661/04preboardoutputstagebemv6.jpg


http://img219.imageshack.us/img219/4129/05preboardphonostagebefyg5.jpg


http://img207.imageshack.us/img207/1094/06preboardpowersupplyserj9.jpg


http://img219.imageshack.us/img219/6610/07preboardtonecontrolsext4.jpg


http://img219.imageshack.us/img219/8541/08preboardriaaphonosectbi9.jpg
Shot at 2008-11-01

Loud & Clear
11-07-2008, 12:13 PM
A few more...

http://img219.imageshack.us/img219/2715/09preboardpowersupplysejx3.jpg

http://img207.imageshack.us/img207/5782/11preboardoutputsectionmc7.jpg


http://img216.imageshack.us/img216/3854/12buffersectionofboardaat4.jpg


http://img207.imageshack.us/img207/996/13bottomofpreboarddefluzh9.jpg


http://img207.imageshack.us/img207/779/15oxidizedinputjacksbefid0.jpg


http://img216.imageshack.us/img216/6789/16goldplatedjacksafter2ir0.jpg


http://img219.imageshack.us/img219/7558/17goldplatedjacksafter3jp5.jpg


http://img216.imageshack.us/img216/8753/18functionselectorledscbu8.jpg

Loud & Clear
11-07-2008, 12:16 PM
More...

http://img219.imageshack.us/img219/8600/19volumebalanceattenuatqa7.jpg


http://img219.imageshack.us/img219/4821/20ahhlookslikeitsreadytnb1.jpg


http://img207.imageshack.us/img207/8969/21anotherfullafterveiwkb5.jpg


http://img216.imageshack.us/img216/5075/22finished1db1.jpg


http://img207.imageshack.us/img207/1673/23finished5jw3.jpg