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    Junker PAS-3 photos

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    brierpath

    Posts : 1
    Join date : 2012-06-05

    Junker PAS-3 photos

    Post by brierpath on Tue Jun 05, 2012 9:35 pm

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    I bought this years ago in a pawn shop for $5.00. I now need it to drive an ST35 clone for my workshop. Should the filament supply be rebuilt first off, or would it just need the electrolytics replaced? It looks like somebody has been inside it, as it has a fuse holder on the back panel and some caps look out of place. I will be perusing all PAS-3 posts for info.

    Thanks,
    Bill

    anbitet66

    Posts : 132
    Join date : 2009-12-23
    Location : Valley Stream, NY

    Re: Junker PAS-3 photos

    Post by anbitet66 on Wed Jun 06, 2012 7:15 am

    Bill,

    I'd start with the quad capacitor, if it was never replaced. The filament supply has had its electrolytics replaced since they are much smaller than what was used originally, though they may need replacing as well. The next step would be to replace the selenium rectifier with a pair of 1N400x diodes. There are already some new caps visible (orange drops, yellow tubulars) so change out the Black Cat's too. You could even list them on eBay and pay yourself back for the purchase of the PAS3 Smile . Last, check each resistor for drift, and replace any out of spec. A quick hit with contact spray, and you would be good to go.

    Bare minimum would be to disconnect the quad cap, and put 4 discrete caps under the chassis and check the rest of the preamp for shorted caps and fire it up.

    GP49

    Posts : 733
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: Junker PAS-3 photos

    Post by GP49 on Wed Jun 06, 2012 6:19 pm

    I wouldn't waste any time with the original selenium rectifier. Replace it with silicon diodes while you have it open to do ANYTHING. Probably it is already going high-resistance, resulting in low filament voltage. If that happens the preamp will suffer from slow warmup, fuzzy/soggy/leaden sound, poor transparency, lack of headroom, athlete's foot, fleas and hay fever.

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