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    Test PAS-3 Volume Control

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    JohnM24018

    Posts : 3
    Join date : 2018-03-28

    Test PAS-3 Volume Control

    Post by JohnM24018 on Mon Apr 09, 2018 12:00 pm

    Sometimes my Dynaco PAS3 will loose the left channel either partly or completely. I use FM-MPX input. Like I say most of the time it works fine but sometimes it doesn’t. My tuner, cassette deck, dish TV, DVD player and computer inputs are collected to and distributed from a Radio Shack 6 position switch. To correct the left channel problem I turn the selector switch to TAPE HEAD and turn the volume up to about ¾. This produces a variable noise, a crackle then it is fixed. I purchased the unit used in about 1972 but recently have installed the SDS Labs capacitor diode upgrade adding the optional fuse. In addition new PC-5 & PC-6 boards and PC-5 tubes. I don’t use a phonograph with this system. I have moved the tubes around to no effect.
    1. Any thoughts?
    2. When I added the SDS Labs capacitor board I used 18 gauge stranded wire because it was available locally. It was a little thick. What gauge was used from Dynaco and what is it called? It is single stranded in my unit. I would intend to purchase it on the common auction site because it is easily available and replace the 18 gauge.
    3. I have just finished a Gain Clone style system. I can now spend some time putting my pre amp back to right. In reading the Forum a new Volume Control Potentiometer was recommended. I have ordered this and will prophylactically replace the old one. I have the original manuals PAS3 & Stereo 70. I intend to check the voltages at the 12 AX7 tubes so with the unit on do the tubes need to be installed? Does there need to be either or both a live input or output to powered up amplifier?
    4. Do the PC-5 & PC-6 boards interact with each other? Like I said I don’t use a phonograph with this system.
    Any help will be appreciated. Thanks John
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    peterh

    Posts : 1014
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Test PAS-3 Volume Control

    Post by peterh on Mon Apr 09, 2018 12:48 pm

    I would start by some 5-56 on the selector segments. Spray, and turn the selector back and fore
    a number of times. Some drops on the shaft will make it lubricated and easier to move.

    The PC6 board does RIAA ( phono input) PC5 is line level amp. But as the filament and powersuplly
    is done both boards is needed.

    I did not understand the question about "gainclone" Is this another amp ?

    JohnM24018

    Posts : 3
    Join date : 2018-03-28

    Re: Test PAS-3 Volume Control

    Post by JohnM24018 on Tue Apr 10, 2018 8:56 am

    Yes, the gainclone is a TI 3886 amplifier chip. It is just something I can listen to while I repair my Tube system in case it takes a long time.

    I will try to locate the 5-56 in town.

    Thank you for your direction. I will start there.

    John


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