Haze 40 power switch led?

Discussion in 'The Workbench' started by Olddogmike, Feb 18, 2021.

  1. Olddogmike

    Olddogmike Member

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    I have just acquired my Haze 40 amp, so I plugged it into power played for a practice session, turned off and went away for the day. I went to switch it on today and noticed the power switch led was showing a very feint glow, I had to unplug from the mains to get it to disappear. Any ideas why this should happen.
     
  2. KraftyBob

    KraftyBob Well-Known Member Gold Supporting Member

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    Looking at the schematic for your amp the light is after the power switch and before the transformer. Is it possible your switch is not working correctly and needs to be firmly pressed to shut off? Possibly a little voltage leaking through?

    17AC60CC-A26B-48C7-AC41-2300032222E9.jpeg
     
  3. Olddogmike

    Olddogmike Member

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    With.the the power unplugged, do you think a squirt of contact cleaner would hep?
     
  4. KraftyBob

    KraftyBob Well-Known Member Gold Supporting Member

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    Couldn’t hurt. Then work the switch back and forth several times.
     
  5. Olddogmike

    Olddogmike Member

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    Tried that, didn't help, its very feint but still there.
     
  6. KraftyBob

    KraftyBob Well-Known Member Gold Supporting Member

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    It has to be your switch as there’s nothing on the other side that can back feed it. Also, since unplugging the amp it shuts off the light that reinforces the issue being the switch.

    How comfortable are you with electronics? If you have a switch laying around you can temporarily wire it in place of the amp switch to confirm. Then order a replacement.

    In the meantime just unplug the amp when you’re done.
     
  7. Olddogmike

    Olddogmike Member

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    I will have to see the config of the switch as my local electronics store sell a illuminated switch for $4.95 its dpdt config. I am far from being expert, but I managed a Tandy Electronics ( Radio Shack) store for many years, so I understand the basics but not a qualified tech.
     
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  8. KraftyBob

    KraftyBob Well-Known Member Gold Supporting Member

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    I loved Radio Shack. Sad that they are no longer around.

    Good luck with the switch and please report back when you’re done. This way if someone else is having a similar issue they can see what works.
     
  9. Adieu

    Adieu Well-Known Member

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    Capacitors?

    Also, is it new or used? If it was repaired with a modern LED as a replacement, those can stay faintly glowing in "off" mode in certain circuit designs.

    For example, I replaced the edison bulb on our microwave with an LED. It used to go Dull - Dim - Off (Hi - Lo - Off), now it goes Bright - Flicker - DimOn.
     
  10. KraftyBob

    KraftyBob Well-Known Member Gold Supporting Member

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    Where would the voltage come from? The caps are on the other side of the transformer and since DC voltage doesn't pass through a transformer I don't know how it could power the light. I was initially thinking about this too, but then looking at the schematic I don't see how.
     
  11. Max Gahne

    Max Gahne Active Member

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    I'm not familiar with a Haze 40 or that particular arcolectric switch but it looks like the lamp is in the switch itself. If so I don't think the Marshall schematic is complete in that area. I don't recall ever seeing a 120V LED lamp in an amp and I know the arcolectric switches used in DSLs use neon lamps, not LEDs. So I suspect there's more internal circuitry in the switch lighting circuit than Marshall shows - I think they're just showing a black box contraption for the switch internals since it's not servicable - and that is where the voltage is coming from. None of that matters, the problem is in between the transformer mains and the wall outlet and pretty much can only be the switch. For myself I'd just order a new switch without looking much further.
     
    Last edited: Feb 19, 2021
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  12. Olddogmike

    Olddogmike Member

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    I am down under in Australia, we are on 240 volts alternating current.
     
  13. Olddogmike

    Olddogmike Member

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    Well I finally found time to pull the back off and investigate. I found a wiring diagram for the switches for marshall amps on line. It showed pos and negative being switched through to the transformer. On the amp I just bought, the pos is wired through the switch, but the negative wire going to the transformer was connected to the input terminal on the switch, and the negative from the power socket was connected to the center terminal on the switch which should be the output connection for negative. Strangely enough the amp works but the red light on the switch just turns dim when the power is turned off. Testing the switch , I get continuity on the positive terminals when switched, but nothing on the negative regardless of the switch position.
     
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  14. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    If it was me I would get the right switch, using the Marshall part number before I would drive myself nuts trying to figure out why the $4.95 switch doesn't work. Find the the right part.

    And for what its worth my Haze 15 goes totally dark when its shut off.
     
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  15. Olddogmike

    Olddogmike Member

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    Getting a switch replacement is not that easy, we don't have a Marshall spares shop here.
     
    Last edited: Feb 21, 2021
  16. Olddogmike

    Olddogmike Member

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    Well its all fixed now using a third party switch. I pulled the original switch and dismantled it, and found one of the two contact nipples was sticking and not releasing to disconnect the contact. Some cowboy had left the positive to switch through, but connected the negative to the sticky terminal which would not disconnect. I tried servicing the original switch without success, but it gave me the information I was seeking printed on the side of the switch body., telling me the lamp voltage which was the same as the third party switch. The only difference now is the new switch has full face illumination where the original one was just a led size.
     

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