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Thread: Dodgy selector switch

  1. #1
    Join Date: Oct 2012

    Location: West London

    Posts: 127
    I'm Steve.

    Default Dodgy selector switch

    I have a VTL 2.5 pre and the selector switch has been playing up for a while.

    It goes from left to right Phono, Aux, Cd and then a couple of others.

    When I select one of the first 3 it most of the time plays on the right channel only and I have to gently twiddle it to regain the left channel.

    I have opened it up twice and liberally sprayed it with contact cleaner as well as turning it frequently but it doesn't make it better.

    Is there anything else I can do? Would WD40 help or have I been googling too much?

    I suppose worst case I replace it but not so easy with a US amp.

    Any suggestions from the experts on this site much appreciated.

    Cheers,
    Thorens TD550, Ortofon 12", Ortofon Jubilee or Koetsu Black; Rothwell MCL SUT, VTL 2.5 pre, XTC POW 1 power; Naim CD5x; KEF Reference 3.2's; Van den Hul interconnects and speaker cables.

  2. #2
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,450
    I'm Chris.

    Default

    The switch in your VTL pre appears to be be 6 contacts with 2 poles.
    If it has failed you have a few choices - replace it with the same or preferably a better design of switch
    Secondly you could arrange the contacts instead to be on relays - which are pretty reliable as far as contacts go.

    With relays there is a coil usually driven with a 12v source and ideally a transistor or mosfet to assist , you also need a diode
    anode to the lower end of coil and cathode to upper to stop what is called back EMF when the relay switches.
    With relays there are Normally ON and Normally OFF contacts - ie when the relay coil has no power the Normally OFF contacts
    are closed and when powered they switch to the Normally ON contacts - thus providing a switch.

    Other methods of switching are with contactless opto methods

    First step will be to get a schematic diagram for your unit, and ask VTL about replacing the switch to see if they stock that part.

    I will check back here if you need further help.

  3. #3
    Join Date: Oct 2012

    Location: West London

    Posts: 127
    I'm Steve.

    Default

    Hi Chris,

    Thanks for the in depth response.

    I can get it to work by playing around with it which is why I thought the contacts were possibly dirty.

    It is a rotary switch and I tried vacuuming and then using contact cleaner.

    I have a tech guy I use who also does work for the distributor as replacing/ changing or going down the relay route is beyond my skill set.

    I was really trying to find out if there are any easy fixes that might work to avoid replacing etc. It is more the delay when it away as everything seems to take an age to fix.

    I have read that WD40 can help with contacts but don't know id this is some old wives tale or not.

    When it is on song this is the best preamp I have ever owned.

    Cheers,
    Thorens TD550, Ortofon 12", Ortofon Jubilee or Koetsu Black; Rothwell MCL SUT, VTL 2.5 pre, XTC POW 1 power; Naim CD5x; KEF Reference 3.2's; Van den Hul interconnects and speaker cables.

  4. #4
    Join Date: May 2016

    Location: Much Wenlock

    Posts: 1,079
    I'm Gary.

    Default

    Quote Originally Posted by Slawts View Post
    Hi Chris,

    Thanks for the in depth response.

    I can get it to work by playing around with it which is why I thought the contacts were possibly dirty.

    It is a rotary switch and I tried vacuuming and then using contact cleaner.

    I have a tech guy I use who also does work for the distributor as replacing/ changing or going down the relay route is beyond my skill set.

    I was really trying to find out if there are any easy fixes that might work to avoid replacing etc. It is more the delay when it away as everything seems to take an age to fix.

    I have read that WD40 can help with contacts but don't know id this is some old wives tale or not.

    When it is on song this is the best preamp I have ever owned.

    Cheers,
    Hi,

    Wouldn't think that WD 40 is a good idea, primarily used as a penetrating fluid and leaves an oily deposit. It can also displace damp used like this on car engine electrics under bonnet. Perhaps this is where the old wives tale comes from?

    Someone else may come along and have more knowledge on WD40 and selector switches, but I would have thought that contact pads and oil film don't belong together .

    Gary
    It is easier to seek forgiveness than to ask permission

    Rules are meant for the obedience of fools and the guidance of wise men

  5. #5
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,450
    I'm Chris.

    Default

    Hi Steve
    The you Tube video here shows some careful cleaning of what looks to be a well designed type of switch, it might give you some ideas for doing
    yours. WD40 No it can deteriorate the switch body

    Of course always power down, Turn OFF at your power point and generally be aware of where power enters and is stored in capacitors
    **** leave for a while before opening top cover to do cleaning of the switch in yours
    https://www.youtube.com/watch?v=0ylr7CXFIhs

  6. #6
    Join Date: Jan 2009

    Location: Essex

    Posts: 21,424
    I'm openingabottleofwine.

    Default

    Use a specialist contact cleaner, readily available from on-line sellers. I wouldn't use WD40 as an electrical contact cleaner: it may initially be successful, but that will be short lived and the situation afterwards will be worse.
    Barry

  7. #7
    Join Date: Oct 2012

    Location: West London

    Posts: 127
    I'm Steve.

    Default

    Thanks gents.

    Chris that video is great. I just sprayed on the switch cleaner so maybe have not properly cleaned.

    I have some Horizon contact cleaner so might try that with cotton buds otherwise Deoxit looks good. Might stock that in Halfords or any good DIY store.

    I will report back hopefully with a functioning preamp.

    Cheers,
    Thorens TD550, Ortofon 12", Ortofon Jubilee or Koetsu Black; Rothwell MCL SUT, VTL 2.5 pre, XTC POW 1 power; Naim CD5x; KEF Reference 3.2's; Van den Hul interconnects and speaker cables.

  8. #8
    Join Date: Oct 2012

    Location: West London

    Posts: 127
    I'm Steve.

    Default

    No so good as it is a sealed unit. I tried to spray down the gaps where it joins the PCB and then use a pipe cleaner but no luck.

    Is this a take apart and if so how?

    Many thanks,

    [IMG]9024.jpg[/IMG]
    Thorens TD550, Ortofon 12", Ortofon Jubilee or Koetsu Black; Rothwell MCL SUT, VTL 2.5 pre, XTC POW 1 power; Naim CD5x; KEF Reference 3.2's; Van den Hul interconnects and speaker cables.

  9. #9
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,450
    I'm Chris.

    Default

    Hi Steve
    The image for some reason did not attach, but I found a video of your preamp
    https://www.youtube.com/watch?v=rwPts8dKHck

    I see the switch is on the rear circuit board, being turned via a long shaft. It looks to me like it can be undone from
    the shaft if you need to replace it, which would also involve removing the rear circuit board. It looks a bit like a sealed Alpha
    or similar brand switch, that Yes would be difficult to clean. As for replacing it, you would need to desolder it from the
    circuit board using solderwick - which will enable a replacement to be much easier to put in. Its a bit of a job
    but not too hard.

    I would contact VTL,first maybe refer them to this thread, and see what they advise https://vtl.com/contact/
    as they no doubt have a well known procedure for replacing the switch.

    Cheers

  10. #10
    Join Date: Oct 2012

    Location: West London

    Posts: 127
    I'm Steve.

    Default

    IMG_9023 (2).jpgIMG_9024 - Copy.JPG

    Hopefully pics now work
    Thorens TD550, Ortofon 12", Ortofon Jubilee or Koetsu Black; Rothwell MCL SUT, VTL 2.5 pre, XTC POW 1 power; Naim CD5x; KEF Reference 3.2's; Van den Hul interconnects and speaker cables.

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