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Naim 32.5 question regarding mono/stereo switch

Discussion in 'audio' started by Nye Samuel, Oct 18, 2020 at 7:16 PM.

  1. Nye Samuel

    Nye Samuel pfm Member

    I have just bought a 32.5 and have the RSL loaner set...Z250V (321), Z301 (729) and MM phono boards and no problems so far...the rest of system is Hicap and 110...source: vinyl, CD and tuner.

    Let me explain. I was listening to vinyl via phono 1 and was only getting sound from one I flicked the mono/stereo to mono and got sound in both channels.

    So I opened up the 32.5 and checked the phono boards were solidly in place and the phono cables from the TT were fully in place; both boards and cables were fully engaged. I tried again...again phono 1(vinyl) was wrong...this time on stereo one channel (left) was fine but the other channel (right) was very quiet but audible...switching to mono...the sound became balanced but the right channel became very quiet again. I switched phono 1 and 2...and it was the same but I noticed if I then used CD/ would work both channels in stereo and then I found the phono 1 (vinyl) worked fine in stereo...What has happened? Have I got a problem with the mono/stereo toggle switch?
  2. DaveMc64

    DaveMc64 pfm Member

    The mono switch works by connecting pins on the buffer boards. In your case they're on the z301 and daughter board - assuming they implemented it. Given your symptoms I'd firstly check the ribbon connector between the two boards.

    Edit- Didn't see it was ok on cd - probably not the ribbon cable then.

    Could be the selector switch.
  3. Nye Samuel

    Nye Samuel pfm Member

    I have emailed Kit...he thinks it could be the selector switch and recommend me turning it vigorously back and forward and using a spray cleaner on the switch... Any recommendations on a suitable cleaning spray?
  4. DaveMc64

    DaveMc64 pfm Member

  5. booja30

    booja30 pfm Member

    Don't be too vigorous with the selector though. The selectors inside CB and olive preamps (made by Alps?) haven't been made for a while and are kind of complicated. It's got a part behind the knob that pushes and pulls on a metal ribbon that moves a sliding selector mechanism in the back.

    Fortunately, the mechanism in the back is the only part you'd need to spray, and it's not fully enclosed. I'd wad some TP around it before spraying to keep the fluid from getting everywhere. If there is any mess afterward, soak it up and then maybe do a little cleaning with some alcohol and a swab.

    In this photo, the actual selector mechanism is the vertical silver part to the right of the vertical boards:


    All the part behind the knob does is convert rotary movement into push/pull movement to move the metal ribbon.
    Last edited: Oct 19, 2020 at 11:00 AM
    cctaylor likes this.
  6. cctaylor

    cctaylor pfm Member

    Perhaps you can lubricate the ribbon mechanism with a silicone lubricant. Apply carefully with a cotton bud.

    I would avoid WD-40 or similar as over time they dry out and become sticky. This why I never use these products on locks, they work as a quick fix but they do cause problems later on.

    Use a good switch cleaner on the actual switch assembly on the PCB.
  7. Nye Samuel

    Nye Samuel pfm Member

    Any suggestions as to a good silicon lubricant? WD-40 do a contact cleaner for electrical and electronics which different to the lock stuff.
  8. booja30

    booja30 pfm Member

    I don't know why the ribbon would need lubricating. It's a stainless(?) ribbon in a plastic sleeve. Even if it was binding up it doesn't seem like it could be the cause of the problems in the first post.

    If you don't have contact cleaner yet, maybe go for Servisol Super 10? Lots of people on PFM will say Deoxit is the only way to go. I used to have some, but since we moved to Europe I've haven't been able to find it under 30€ delivered from anywhere I usually buy from. Servisol is very well rated and under 10€ a can ( I'm never going to use a whole can, so I'd rather get Servisol and a good bottle of wine. :)
  9. Pine Marten

    Pine Marten pfm Member

    Servisol has always worked for me in all kinds of switches and noisey pots. Just work the rotary selector normally a few times and be fairly generous with the servisol to flush out any grot. The RSL boards certainly bring the performance of the 32.5 right up to another level of detail and depth whilst preserving the 32.5's general character.
  10. Nye Samuel

    Nye Samuel pfm Member

    Ok..I used the contact cleaner and not much difference.

    I am using RSL MM Phono boards.

    I tried the phono with the phono plugs as they should be...sound from left speaker and nothing from the right...then I switched the phono plugs and got sound from right speaker but not the left.

    I substituted a 62 and initially only one channel could be I switched the phono boards and sound came from both channels and switched the boards again...and again sound in both I put the phono boards back in the 32.5 and sound in both I put the sleeve back on and all the inputs...phono, cd and tuner and sound in one dismantle everything again (I had used deoxit contact cleaner on phono plugs and sockets and lugs on which the phono boards connect to the motherboard) and this time after everything is put together....sound on both channels via phono (never been a problem with cd or tuner)...cured?? No....I notice silence on the right when going to check tuner...I turned on the tuner (didn't play the tuner)... suddenly, both phono channels can be heard in stereo...So seriously, I do not have a clue as to the problem that is causing the intermittent fault on the phono stage...Any suggestions?
  11. Nye Samuel

    Nye Samuel pfm Member

    Ok..I have left the TT for 30 minutes and again only one channel...left...I turn on the tuner but don't play it...both phono channels are working.
  12. DaveMc64

    DaveMc64 pfm Member

    This bit would imply a fault in the signal from the TT - maybe in the BNC connector.
    But that doesn't tie in with the rest of the symptoms you're describing.

    Could there be more than one intermittent fault?
  13. Nye Samuel

    Nye Samuel pfm Member

    That is always a possibility...the 32.5 has gold plated RCA sockets...and not BNC.

    The problem is either: (1) The 32.5 (2) The RSL phono boards (3) The turntable.

    I tried again this morning and the problem persists and turning on the tuner did not help.

    First thing I did was change phono sockets...and changed CD was now phono 1 and vinyl was phono 2. CD was fine but vinyl was hit and mainly miss. Then I switched the phono boards and that was no different.

    My TT is away being fixed and I have a loaner...but I have noticed that when I touch the TT I can hear it through the speakers as a hum...the earth lead is securely attached to the earth point on the 32.5....and if I repeatedly jiggle the arm cue...I get sound in both channels. I am beginning to think the issue is with the TT and not the 32.5 or RSL mm phono boards. I further think the stereo/ mono button bit is a red herring...I will getting my own TT (repaired)... we shall see and hear....or not.

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