Fisher 500 mono no sound?

Discussion in 'Fisher' started by biminyrd, Oct 11, 2017 at 11:01 PM.

  1. biminyrd

    biminyrd New Member

    Messages:
    17
    Location:
    greensboro, nc
    I found a fisher 500 mono stereo receiver on the sidewalk a few years ago (yes!)
    I didn't really know what I found until I plugged it in and connected my speakers. My boston's never sounded so good.
    I got an initial cloud of burnt dust and then everything was great. After about 20 - 30 hours of playing all of the sudden the sound went out. There was not sound or anything.
    it seems like all of the tubes light up, but I don't know where to start trouble shooting or what to test or how.

    I own vintage scooters and the electrics can be complicated and a bit messed up once the farmer gets a hold of them, so I'm not a newbie to wiring and soldering, or tracing connections, I just don't know circuit boards or tubes or stereos.

    Any help is appreciated.

     
  2. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    It's likely a burnt resistor in the power supply section, but before you go tearing into it to take a look, realize that a unit like this produces at least 400 vdc when operating, so unless you're familiar with HV safety practices, then familiarizing yourself with them is the very first order of business before you do anything else. Next, a good underside shot will help to provide some basic clues. Finally, realize that a unit of this age should have some basic restoration work due to it, not only to promote long term dependability, but also to ensure that damage to irreplaceable components isn't done by components that are replaceable. Beyond this, you'll find plenty of folks here willing to help you get the most out of it.

    I need to know where you walk!!

    Dave
     
  3. biminyrd

    biminyrd New Member

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    Location:
    greensboro, nc
    Thank Dave!

    do you have a link to the HV Safety Procedures? or can you point me in the right direction?
    I'll post an underside shot later when I get home and a chance to take the cabinet apart.
    What other restoration work should be done? What is replaceable and what is not?
    I've looked around and haven't found any more information on what to do or where to start. thanks!
     
  4. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    8,846
    Location:
    Ball Ground, GA
    Others may know a specific site, but common sense is the rule of the day, that is the foundation of well established procedures like:

    1. No alcohol while working with a live unit.

    2. Wear socks and rubber insulated shoes when working on a live unit.

    3. When measuring high voltages, keep one hand behind your back. Having clip leads for your meter helps in this regard.

    4. If the environment permits (temp wise), even long sleeve shirts provide extra protection for those new to working on vacuum tube electronics.

    There are certainly others. But the salient point here is to prevent any electric shock from going across your body -- either side to side (one arm and out the other) or from your arm down through your legs. You don't want any electric shock to travel across your heart.

    None of this is meant to scare you at all, but to keep you around here for a long time. There are countless folks here who have worked with this equipment regularly for years, and it is a very safe hobby -- as long as common sense prevails, and you keep your mind on the task at hand. Accidents happen when these two concerns occupy anything less than first place when working with live equipment.

    Also, after working on a live unit, allow at least 5 minutes for all the voltages throughout the unit to dissipate and discharge. The power supply capacitors in these units don't immediately drop to 0 voltage the minute a unit is turned off, so allowing a few minutes for them to discharge to a safe level is important as well.

    You will want to either obtain a variac, or build a Dim Bulb Tester. There are plenty of folks here who can help you with that, and show you the one they made. Simple to make, either device will allow you to turn on a vintage unit sloooowly, rather than all at once, so as to give you a warning if something is not right before applying full power to it.

    The 500 receiver is a beautiful unit. But it's a very good possibility that whatever has failed, did so because another part failed taking out the part that has now caused the unit to produce no sound. That's why besides simply getting the unit operating again, some basic restoration efforts are highly recommended as well.

    Dave
     
    Last edited: Oct 12, 2017 at 12:54 PM
  5. larryderouin

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

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    In addition to Dave's list, Put your jewelry in a box BEFORE approaching the bench. I can't begin to tell you when I was working EMS, how many people over the years, I transported to the E.R. that had welded their wedding rings to a chassis, or a grounded point, with their finger in it. A few got zapped enough to have us do CPR on them but luckily all survived. Best to use a meter to check for voltages on the Cap Can's before sticking any fingers inside the chassis.

    In addition to NO ALCOHOL, I have to add NO Plant matter either, whether it's bud, leaf or stems and seeds.
     
  6. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

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    Awww Geeze guys. No alcohol??? Kiddin of course :)
     
  7. larryderouin

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

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    AFTER you're done for the Night Al, After you're DONE. :rflmao:
     
  8. TubeDroid

    TubeDroid New Member

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    Location:
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    On thumb rule I've been told twice by college professors is "If you're right handed, use your right hand and keep your left hand in your pocket, and if you're left handed, put your left hand in your pocket and keep your right hand where you can see it."
    Reason being that if you are going to get zapped, you definitely don't want the current running through your heart; old techs aren't old by accident; they're old because they use their right hand.
     
  9. biminyrd

    biminyrd New Member

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    Location:
    greensboro, nc
    Thanks Dave for the detailed list.
    cool, so plug the dim bulb into the outlet and the amp into the dim bulb, if the bulb lights up it means______?
    Is there a list or order in which things need to be tested beyond this? or a list or tutorial somewhere? (shouldn't that exist here as a sticky?)
    thanks!
     
  10. Rockyhill

    Rockyhill 148 State Street Subscriber

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    I wish my sidewalk had stuff like this... nice find!
     
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  11. larryderouin

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

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    As a LEFTIE I take exception to your "professors" statement. He/They come off to me like my 5th grade teacher who was a French Canadian Nun. Back in the 60's LEFTIES were still considered the "Devil's work" and these nuns went to great lengths to make you right handed. This particular nun had a 12" STEEL engineer's ruler that she'd use on your knuckles, by applying the corner edge of the ruler rather than the flat edge. That got stopped quickly that year when I yanked it out of her hand, tossed it out the window, threatened her with insertion of the next ruler, and then walked out of class, and called my father at home. As the NAVY was subsidizing some of the tuition and all of the bus routes to the Catholic Schools at the time in that area of Ct. , the NAVY DISTRICT CHAPLAIN's office and the Diocesan BISHOP got involved. UPSHOT! A Letter to all teachers in the diocese, that any more incidents would result in immediate termination of the teacher, whether a lay teacher or a NUN!

    I've been putting my RIGHT HAND in my back pocket since I was a 10 year old and working with my dad on TV's. A more correct statement from your "professors" would have been along these lines......No matter whether you are LEFT OR RIGHT Handed, USE YOUR DOMINANT HAND ONLY, and keep the other in your back pocket.
     
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  12. TubeDroid

    TubeDroid New Member

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    I'm sure it wasn't disrespect at the time; it was a case of making sure that if you get zapped, current running through your body has a much better chance of bypassing your heart if you use your right hand.
    Maybe that theory's been disproven since the '60's.
    Sorry if you took exception.
     
  13. Tom Bavis

    Tom Bavis Audiophool Subscriber

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  14. larryderouin

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

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    TubeDroid. No real problem. Sorry if I came on a little strong. I'm one of the unlucky few to be a Leftie and Teachers tried to force me to be a Rightie from Kindergarten all the way thru 1 year of college. Both of my Grand-kids are Leftie's and I hope like hell they don't go thru what I did in school.

    Medically there really isn't any difference whether the ingress of the voltage is from the Left or Right Side. The upper 1/2 of the heart is actually centerline, where the sinoatrial node(Upper wall of the RIght Atrium) is located. This node is the Hearts pacemaker.


    Because the left and Right atriums (lower chambers of the heart) are in the left side of the thoracic cavity(just barely btw), This may have something to do with the Prof's and engineers statements back in the 40's, 50's, and 60's. The SinoAtrial node is actually centerline in the thoracic cavity and under the sternum. Defibrilators didn't come out to the U.S. until the 60's and you have Senator Hubert Humphrey's visit to Russia in 1958 to thank for introduction of Defibrilators in the U.S.

    FROM WIKIPEDIA https://en.wikipedia.org/wiki/Defibrillation#Manual_external_defibrillator
    In 1958, US senator Hubert H. Humphrey visited Nikita Khrushchev and among other things he visited the Moscow Institute of Reanimatology, where, among others, he met with Gurvich.[32] Humphrey immediately recognized importance of reanimation research and after that a number of American doctors visited Gurvich. At the same time, Humphrey worked on establishing of a federal program in the National Institute of Health in physiology and medicine, telling to the Congress: "Let's compete with U.S.S.R. in research on reversibility of death".[33]

    It doesn't matter whether you are LEFT or RIGHT Handed. If you are grounded to the floor or the chassis and get zapped with a high enough voltage and sufficient amperage, your heart WILL go into an arrythmia . Use your DOMINANT Hand for work and keep the other in your back pocket.

    Now back to our regularly scheduled "NO SOUND from my 500, MONO" Thread.
     
    Last edited: Oct 15, 2017 at 7:41 PM
  15. biminyrd

    biminyrd New Member

    Messages:
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    Location:
    greensboro, nc

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