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    PAS 3 Seemingly bad selector switch

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    blossombone

    Posts : 3
    Join date : 2018-05-29

    PAS 3 Seemingly bad selector switch

    Post by blossombone on Thu Nov 15, 2018 11:52 am

    Hi all,

    I bought a pas 3 several months ago on Ebay. I bought it as is, and when I go to hook it up, I have to put the selector in between and twiddle it to make sound come out of both channels.

    Sometimes music comes out of all the inputs even though only one has something plugged in.

    I have cleaned the switch several times and no luck. I took it to the local guitar center and the tech can't find the problem. We are both unsuccessfully looking for a replacement switch.

    Could there be another problem?

    I can solder and have a multi tester but am definitely not an electronics genius.

    Any help is appreciated.

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    Peter W.

    Posts : 1003
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: PAS 3 Seemingly bad selector switch

    Post by Peter W. on Thu Nov 15, 2018 12:56 pm

    These wafer switches are notorious, however, they are mostly able to be salvaged.

    Before you do anything, take off the front faceplate and re-secure all the lock-nuts and make sure the stop-tooth on the selector switch is properly in the small hole in the back faceplate. If that bends or fails, all sorts of havoc takes place with the switch. Then:

    a) First, clean the switch thoroughly with a 100% evaporative cleaner - something designed for vintage TV tuners or the like. You don't want residue for the next steps.
    b) Then with a good lens and a few dental picks, check for loose parts, bent wipers, loose springs and such. Sometimes, a wafer will twist or slide on the shaft. A touch of gap-filling super-glue will solve for that problem. Glue will also secure loose contacts.
    c) Check carefully for overlaps -where the wiper may not have cleared the nearby contact - also due to wafer-creep.
    d) When everything is tight, secured and all clearances are good and contacts firm, use a lubricating contact cleaner - SPARINGLY - to finish the job.

    Dental picks will be your best friend in this exercise, and a good lens if you are not seriously myopic - in which case your eyes will magnify enough at close range. Lastly, this is a mechanical exercise, not much to do with electronics, so not to worry about a lack of expertise or genius in the field.

    Best of luck with it!
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    peterh

    Posts : 1068
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: PAS 3 Seemingly bad selector switch

    Post by peterh on Thu Nov 15, 2018 4:23 pm

    Check the tape switch for correct function, some cleaner and some exercise might resoove some problems.
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    j beede

    Posts : 472
    Join date : 2011-02-07
    Location : California

    Re: PAS 3 Seemingly bad selector switch

    Post by j beede on Sat Nov 17, 2018 12:26 pm

    Of all the things "wrong" with the PAS, the switches are at or near the top of the list. The "selector" switch is curiously named as you can hear all of the devices (attenuated) connected to the PAS regardless of the switch's position. If this doesn't sound familiar to you, you can move along--nothing more to see (read) here.

    Get yourself a 20th century two pole, six position rotary switch, twenty feet of your favorite ~3mm diameter shielded cable, the rear RCA panel kit from dynakitparts, and some shrink tube to replace the rat's nest in there now.

    I am not much of a fan of the PAS... but can say that replacing that selector switch, RCA panel, and the volume control turned a sow's ear into a burlap purse.

    I hope you will excuse me as I log out before the inevitable bloviating begins
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    erhard-audio

    Posts : 44
    Join date : 2017-04-07
    Age : 60
    Location : Tucson, AZ

    Re: PAS 3 Seemingly bad selector switch

    Post by erhard-audio on Sat Nov 17, 2018 1:27 pm

    j beede wrote:Of all the things "wrong" with the PAS, the switches are at or near the top of the list. The "selector" switch is curiously named as you can hear all of the devices (attenuated) connected to the PAS regardless of the switch's position. If this doesn't sound familiar to you, you can move along--nothing more to see (read) here.

    Get yourself a 20th century two pole, six position rotary switch, twenty feet of your favorite ~3mm diameter shielded cable, the rear RCA panel kit from dynakitparts, and some shrink tube to replace the rat's nest in there now.

    I am not much of a fan of the PAS... but can say that replacing that selector switch, RCA panel, and the volume control turned a sow's ear into a burlap purse.

    I hope you will excuse me as I log out before the inevitable bloviating begins

    I totally agree here. Another weak point in the PAS was the power supply, especially more so now after all these decades.
    It's all very well wishing to keep things 'original', but in the case of a decades-old PAS or SCA etc. it really makes no sense. Mechanical and electronic parts suffer from age, just like a lot of us Wink, unfortunately, we humans have yet to have 'replacement' parts or upgrades for our bodies, but it is a relatively easy thing to do with old electronic gear. How far you upgrade is of course entirely up to you, but at the very least, do strongly consider the parts and items mentioned above and here.
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    peterh

    Posts : 1068
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: PAS 3 Seemingly bad selector switch

    Post by peterh on Sat Nov 17, 2018 2:24 pm

    The GOOD thing about the PAS switch is that it grounds unused inputs to prevent "bleed".
    It might be that function that has gone wrong with the original posters PAS.
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    Peter W.

    Posts : 1003
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: PAS 3 Seemingly bad selector switch

    Post by Peter W. on Mon Nov 19, 2018 9:48 am

    peterh wrote:The GOOD thing about the PAS switch is that it grounds unused inputs to prevent "bleed".
    It might be that function that has gone wrong with the original posters PAS.

    Exactly this, but for the brutal fact that the selector switch used was the cheapest available at the time, and Hafler probably attempted to drive the price down yet further. For all that, they are repairable if not missing pieces or have worn-through wipers or springs. Usually, the repaired state together with proper lubrication leaves it in better condition than when 'fresh' from the factory - such as it was. On the power-supply, it is true that it is not very resilient, and does not tolerate stress well (specifically, the transformer). But, if fair attention is paid to the state of the filter and filament-supply capacitors, it will last indefinitely.

    blossombone

    Posts : 3
    Join date : 2018-05-29

    Re: PAS 3 Seemingly bad selector switch

    Post by blossombone on Tue Nov 20, 2018 6:39 am

    First of all, I want to thank everybody for their responses.
    I took it to a guy who fixes guitar amps.  He fixed none of the issues, but since I got it back I have figured out that the channel dropping has to do with the blend switch.  
    When it's in full stereo mode one channel or the other drops out. Depending on where the switch is.  Also, there is less signal from the left channel.
    I may post a video on YouTube to show everybody the problem.
    Thanks very much again for the help!
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    Peter W.

    Posts : 1003
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: PAS 3 Seemingly bad selector switch

    Post by Peter W. on Tue Nov 20, 2018 8:11 am

    blossombone wrote:First of all, I want to thank everybody for their responses.
    I took it to a guy who fixes guitar amps.  He fixed none of the issues, but since I got it back I have figured out that the channel dropping has to do with the blend switch.  
    When it's in full stereo mode one channel or the other drops out. Depending on where the switch is.  Also, there is less signal from the left channel.
    I may post a video on YouTube to show everybody the problem.
    Thanks very much again for the help!

    Same cleaning process on the blend switch. Betcha if you tighten up the spring contacts, it will be much better.

    audiobill

    Posts : 364
    Join date : 2014-03-13
    Location : Philadelphia

    Re: PAS 3 Seemingly bad selector switch

    Post by audiobill on Tue Nov 20, 2018 2:09 pm

    Best move may be to rip out the switch, jacks, circuit boards and power supply and reach out to Holger (Erhard above) for all new parts. Or else sell it on ebay and buy an SP14 from Roy, even better.

    Really nothing special about the PAS3.
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    tubes4hifi
    Admin

    Posts : 1483
    Join date : 2008-11-30

    Re: PAS 3 Seemingly bad selector switch

    Post by tubes4hifi on Thu Nov 22, 2018 5:51 pm

    I'm with beede and audiobill on this!
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    peterh

    Posts : 1068
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: PAS 3 Seemingly bad selector switch

    Post by peterh on Thu Nov 22, 2018 6:17 pm

    I'd say : " Sell it "as is " while it's still unmunged and buy something else for the money. There is
    still people that can repair old PAS and who wants them !
    If you start ripping it apart it will only have value for you and you cannot build much in that
    box unless you replace all innards !
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    PeterCapo

    Posts : 626
    Join date : 2008-12-05

    Re: PAS 3 Seemingly bad selector switch

    Post by PeterCapo on Thu Nov 22, 2018 7:50 pm

    I'll second @peterh here. Someone who wants to put the work into restoring a fifty-year-old PAS to its original glory could find it well worth the effort.

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