What are the dangers of not using a Variac?

Discussion in 'Audio Hardware' started by Edwin Hawley, Jun 8, 2010.

  1. Edwin Hawley

    Edwin Hawley Active Member

    Location:
    Long Island, NY
    Picked up a 1 owner unmodified/unrestored Fisher 500C based on Steve's recent thread. Even has original yellow Fisher tubes. I'd like to hear how she sounds "as is" before sending her out and comes back with many replacement parts. I don't have a Variac and wouldn't know what to do with one if I did.

    Will anything bad happen if I just hook up the speakers and turn her on? It's been several years since she was last powered up. Worked fine up till then.
     
  2. Steve Hoffman

    Steve Hoffman Audiophile Mastering Your Host

    Location:
    Los Angeles
    People, what do you say? I'm not going to be the one to tell him "Eh, what the heck, plug it in and see what happens!"

    Can't you make a poor man's Variac out of a lightbulb and something else simple? Been a while but I remember that much.
     
  3. acjetnut

    acjetnut Well-Known Member

    Location:
    NYC
    Why do you need a variac? Will those amps blow at 120v?
     
  4. acdc7369

    acdc7369 Well-Known Member

    Location:
    Hayward, CA
    Who knows maybe the amp will have a catastrophic meltdown if it hasnt been used for a while and you suddenly give it full AC voltage. Maybe the XFMRs in these things short out after 50 years? I tried asking this question before and getting an answer was an epic fail :cool:
     
  5. reb

    reb Long Live Rock

    Location:
    Long Island
    try searching for an answer on some dedicated audio hardware forums such as AA.
     
  6. TONEPUB

    TONEPUB Forum Resident

    Location:
    Portland, Oregon
    Your biggest problem is you run the risk of blowing a capacitor somewhere. If that happens, you may do more damage. Transformers don't short out without use.

    If you bring the voltage up slowly, it gives the caps a better chance to reform somewhat and if there is a failure, to shut it back down before full voltage does harm to something else.

    If it's been sitting for a long time, it's worth seeking a Variac out or paying a service tech (if you have one nearby) a few bucks to power it up on a bench.

    Sounds like you found a nice piece of vintage gear, why take a chance?
     
  7. KT88

    KT88 Forum Resident

    You could destroy the amp. Probably just the filter caps, but if a tranny goes, it'll be a disaster. Most likely it'll blow a fuse or work fine for a few minutes. I'd not bet on it, just send it off and wait.
    -Bill
     
  8. reb

    reb Long Live Rock

    Location:
    Long Island
  9. seed_drill

    seed_drill Forum Resident

    Location:
    Tryon, NC, USA
    Can't you make one by splicing a dimmer switch into an extension cord? I've thought about doing this for my figural Christmas lights, as I keep blowing them at an alarming rate, and they ain't cheap + they ain't making any more.
     
  10. EC3970

    EC3970 Active Member

    Location:
    Ohio
  11. Edwin Hawley

    Edwin Hawley Active Member

    Location:
    Long Island, NY
  12. ManFromCouv

    ManFromCouv Employee #3541

    There it is. Spend the $50 and get a variac and rest easy. I wouldn't think of getting nice old amp that's been out of use for a while and NOT bringing it up with a variac. If someone is going to cheap-out and avoid buying one, then vintage tube gear isn't for you.
     
  13. Leigh

    Leigh Forum Resident

    Either would be fine, the second one will "only" go to 150 V. They must have different transformers in 'em. I hope you have a voltmeter to test these out on first, that meter isn't very precise. You could make a mark where 110 V is on the device itself.

    Beware: The inputs and outputs bindings expect bare wire. You will have to sacrifice/purchase a couple power cords to get things to work.
     
  14. reb

    reb Long Live Rock

    Location:
    Long Island
    Because you live in the USA and we use 110-120v, then this one:

    http://shop.vendio.com/Evan2002/item/2041770247/index.html

    But I can't vouch for the quality of the unit as I've not tried it myself.

    Those Overseas members that run gear off 220v would want to buy the other one in the link.

    Edit: Plus it says right on the site to e-mail them any questions.
    evan2002@vendio.com <evan2002@vendio.com>
     
  15. McLover

    McLover Forum Resident

    Location:
    East TN
    Unless this unit has been properly serviced in the last 5-7 years, you do need to check it with the voltage gradually increased. If you don't you may risk damaging critical components like the transformers. Most of these units will need all electrolytic capacitors replaced at minimum before they see full line voltage. Cheaper to do that than to risk audio or power transformers (originals hard to find and getting expensive to replace or rewind). Also make sure weak tubes/selenium rectifiers are addressed before full line voltage. Do not power it up without a speaker load connected. Another way to do expensive to repair damage.
     
  16. nightenrock

    nightenrock Well-Known Member

    Location:
    Brooklyn, NY
    Plug it in and see what happens.
     
  17. XMIAudioTech

    XMIAudioTech New Member

    Location:
    Petaluma, CA
    NO.

    The amp's power transformer might blow the dimmer (dimmers are designed to have light bulbs as loads), causing it to run in the full-on position if it goes. You might as well just plug the amp in.

    Use the dimmer for your lights, Use a Variac for the amp.

    -Aaron
     
  18. dividebytube

    dividebytube Well-Known Member

    Location:
    Grand Rapids, MI
    it depends on the unit's value, but I've plugged in plenty of vintage units without using a variac... provided the capacitors aren't leaking or bulging in any strange way. Of course I have my hand on the plug, waiting to pull it if anything starts to smoke or some weird noise happens. I'm my own tech, so replacing some parts is no big deal.
     
  19. Greg1954

    Greg1954 New Member

    Location:
    .
    And if you don't much aptitude for those types of projects (however simple) spare yourself the risk of fire or electrocution too.
     
  20. Edwin Hawley

    Edwin Hawley Active Member

    Location:
    Long Island, NY
    I think I will send it to Terry Dewick and explain to him my desire to keep it as original as possible and to just do what is necessary. If the original tubes are no good, replace em and send the originals back, yada, yada. Thanks to all who responded.
     
  21. McLover

    McLover Forum Resident

    Location:
    East TN
    Terry DeWick will do a superb job getting the old Fisher back to specification and getting you nice, musical sounds.
     
  22. Senn20

    Senn20 Well-Known Member

    Location:
    Madison, WI, US
    This.

    Do you have a tube tester as well? My knowledge of guitar amps tells me that powering up an old amp with bad tubes is hard on the caps, and if the caps go the transformer is next.
     
  23. Edwin Hawley

    Edwin Hawley Active Member

    Location:
    Long Island, NY
    Well, I decided to take a chance and try her "as is" after all. Figured it had only been 6 years and that didn't seem too long. I listened for a few hours yesterday and an hour this morning. I figure if anything bad was going to happen, it would've happened by now. The blue smoke is normal, right? (Just kidding)

    This is my first time listening to cd's through a tube receiver. Wow, what a different experience. All I can say is that it makes my well mastered cd's (DCC's, 35dp's, early mofi's, etc) sound more alive and musical, while bringing out the flaws in others. Had to turn the Hi-filter on while listening to a few early Stones London tracks, something I don't recall having to do with solid state. I regret listening to my newly acquired Abbey Road black triangle last week since I'm sure it would sound great on the Fisher, and it will be some time before I am ready to hear it again. Currently listening to the aluminum MOFI Mars Hotel and it smokes.
     
  24. KT88

    KT88 Forum Resident


    Pun intended, of course.
    :laugh:

    -Bill
     

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