power switch / volume

Discussion in 'Fisher' started by superjojo, Aug 7, 2017.

  1. superjojo

    superjojo Active Member

    Messages:
    154
    power switch/volume.

    I had one fail many years ago. Ive recently started using another fisher but have been using the power strip to turn it on and off.

    Are those switches robust enough to use daily?
     
  2. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    Yes and no.. Best to use a power strip (I do) even though all my switches work perfectly. Volume controls and switched for these are getting harder to find. Hope this helps.... Al
     
  3. notdigital

    notdigital AK Subscriber Subscriber

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    If your unit has had a thermistor installed, then the power will ramp up slowly and avoid the electrical spark, or arching, that occurs in an "unprotected" switch. The repeated spark in the switch is what eats away at the contact spring which eventually breaks rendering it useless. I've repaired the defective switches in all my units that needed it and they all have thermistors. Still, I rarely use the switch opting instead to throw the switch on the power strip or the connected bucking transformer. Sorta silly but I really don't want to crack open the switch for repairs ever again if I could help it.
     
  4. fahfisher500

    fahfisher500 New Member

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    35
    I had this problem and got Mark Oppat to make me a new one which has worked flawlessly since I installed it. FullSizeRender.jpg
     
  5. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    I would think that if it feels tight as you operate it, it's probably ok. One or two on/off cycles a day probably won't hurt it, but the suggestions above won't hurt it. You can certainly use a power strip to turn it on and off which will help the switch. The down side to a power strip is it encourages plugging in everything under the sun to it, then it's overloaded as is possibly the circuit. A better suggestion is a Christmas tree light remote switch. It's a plug you plug in your receiver to, and has a cord with the switch on the end. Single plug, so you aren't plugging in everything under the sun. Easy to make also if you want to go that route.
     
  6. vendo81

    vendo81 AK Subscriber Subscriber

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    Use a QuenchArc across the switch. It's a snubber cap that combines a resistor and capacitor together to suppress arcs on switch contacts. My good friend, who is a retired electrical engineer gave me a bunch of these several years ago and said to use them as it's the arc that damages the contacts. I've been using the switches on my Fisher items, one in particular several times a day and have had no failures yet so I'm guessing that the snubber cap is working. The ones he gave me combine a 220 ohm resistor and a .1 cap. He said in certain cases they can be useful on items that "thump" when turned on/off as well.

    Quencharc.jpg
     
    Last edited: Aug 10, 2017
  7. RS Steve

    RS Steve Tube Junkie Subscriber

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    I install a CL-80 and a jumper wire that connects both contacts of the switch together so it has twice the contact area. Since one lead is used to power the spare outlets on the back, it only takes a small jumper to connect to the other lead.
     
  8. vendo81

    vendo81 AK Subscriber Subscriber

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    I do the exact things you mention as well Steve. Everything helps :)
     
    RS Steve likes this.
  9. Rockyhill

    Rockyhill 148 State Street Subscriber

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    Interesting... I have a Lepai Tripath amp that thumps when turned on/off and had stopped using it for that reason. I had considered using it with a TV but then thought twice due to the thumping. Perhaps I'll try placing one of these across its switch.
     
  10. vendo81

    vendo81 AK Subscriber Subscriber

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    I doubt it would do anything for a surge which it sounds like you have but you can give it a try.. I had a preamp that sent a popping sound into the amp when turned on and off. It eliminated that problem. The amp stayed on for about 20 seconds after turn off or it wouldn't have mattered.
     
  11. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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  12. Rockyhill

    Rockyhill 148 State Street Subscriber

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  13. superjojo

    superjojo Active Member

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    154
    What else is taking a beating by the inrush? Besides the switch.
     
  14. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    Transformer, Voltage on the Main Filter Caps tends not to spike over their rated limit (+50v or so for surge), Rectifier doesn't get a jolt output's son't get a large surge all at once, they geta ramped surge that is lower than usual and can handle it better. Inrush limiter is a variable resistor that is high resistance when cold, and lowers resistance when it heats up. So instead of of everything getting slammed right NOW, they get it ramped up in a controlled voltage increase over a few seconds.

    Compare it to Gasoline: 100-120 Octane AvGas burns literally explodes compared to 87 Octane gas. It requires an engine with a Very High compression ratio ( about 12.5 or higher to one with a lot of initial timing BTDC). 87 burns relatively slow and requires an engine with a compression ration of about 8.0 to 8.5 and not a lot of timing BTDC. Put 100-120 AVGas in your car and it'll blow itself apart in a couple of seconds to a couple of minutes because of the burn rate of the 110-120 AVgas . Put 87 to 89 in your car and with normal maintenance you can run down the road for a long time.
     
  15. Thumper

    Thumper Active Member

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    Larry, it actually doesn't have a lot to do with burn rate - generally premium fuel has less energy density, and burns at a lower temperature. The "poor" burning characteristics can be offset by more ignition timing and higher compression ratio or boost. More air + more fuel = more powa. Here's a good little article on the subject:

    http://www.caranddriver.com/features/regular-or-premium
     

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