Best single amp tool?

Discussion in 'Amp Central Station' started by King Fan, Jul 8, 2019.

  1. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    I've never found any advantage to ratcheting screwdrivers but I've bought them a couple of times for the one odd tiny star bit I needed at the time. I've owned a few Yankee screwdrivers too, nice tools but I seem to prefer to do my own ratcheting, as opposed to fiddling with the forward/ reverse switch.

    The light bulb limiter though, I just dug out an actual old variac I've had for years but never wired up.
    Looking on ebay for an analog voltmeter, but guessing the voltage numbers on the variac dial are adequate.
    Or I can check with a multimeter if using it to break in a speaker.

    The bigger issue is there are five connections labeled 1 2 3 4 and 5, and I don't know what any of them are.
    I suppose two are the primary winding and two are the secondary, plus a ground for whatever reason?

    Effectively a great tool but I don't know how to use it!

    Might be partly putting off doing a recap on a big old Sound City Hiwatt sort of thing that doesn't work, and that needed a recap and probably a PT when it was last working. PT seemed to be the source of a constant crackling, not heard through the speakers.
    I found a correct used PT for it a couple of years ago and finally bought new filter caps recently.
    I'm lousy with electronics and have a bad record with fixing stuff that has multiple undiagnosed problems.
    Charred parts are no problem, I like charred parts!
     
  2. schmee

    schmee Poster Extraordinaire

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    I have a light bulb limiter, but I have no faith it is needed. Haven't used it in a decade or more. If it was needed then all those vintage 50s-60s amps would've been garbage for not having been started up with one I guess!
     
    Last edited: Jul 9, 2019
  3. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    Have you done a recap and started up with full wall voltage?
    Are you saying new amps didn't get started up on a variac to form the caps?
    Hmmm, never heard this but there are plenty of trends that suggest the old days couldn't have happened...
     
  4. schmee

    schmee Poster Extraordinaire

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    Yes , recap it , and... flip it on! I haven't used the light on a recap for a long time. Seriously doubt Leo or any of the other used a variac to start the amps. But I could be swayed with a video from the 50's! Then there's the millions of TV's and Radios.... and I can just see the guy out on the flight line in the 70's starting up an A4 Phantom and his variac forming the caps.... :>)
     
  5. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    B, but, AC-30s are true class A!
     
  6. Snfoilhat

    Snfoilhat Tele-Afflicted

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    Thread's taken an interesting turn!

    Light bulb limiters limit current. I've never before heard anyone connect their use to helping in some way to gently start up capacitors. An amp drawing a good deal of current (power tubes installed and properly heated) on a light bulb limiter will have a lower B+ because the effective wall voltage will be lower, but my understanding is that this is just a side effect. Without power tubes in, like when the amp's power supply is first built and being tested, the amp draws so little current that the light bulb drops negligible voltage--unless there is a hidden fault.

    I use my limiter every time I start an amp with an unknown problem or an untested fix -- to check for short circuits and to give a simple visual indication of the current being drawn.

    150W bulb in the path of a small combo amp that draws 60-80W at idle will glow faintly.

    I don't think of the current limiter as a variac
     
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  7. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    OK so I forget a lotta stuff, and I recall often reading on the internet that:
    1) you need to start up a recapped amp on a variac.
    2) you can use a light bulb limiter for this if you don't have a variac.
    3) you should start up an old possibly in need of service amp on a variac or light bulb limiter to avoid catastrophic failure.

    Do we need to form new caps at startup by using a variac?
    Or is that some old internet myth?

    If it's a myth, what do amp techs need a variac for?
     
  8. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    For tools I still want I'd say a 200w or bigger soldering iron for filter caps ground to a big steel chassis.
     
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  9. Snfoilhat

    Snfoilhat Tele-Afflicted

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    I have the same question! But a bulb limiter won't work as a good variac for the reason I mentioned above. It's Ohm's law. By the time we are putting power tubes in a new or newly refurbished amp, the caps in the power supply have already been exposed to whatever your total variac or wall voltage is, because the bulb, an enormous resistor, can only drop voltage proportional to the amount of current through the bulb, which is pretty small -- just the heaters, which might be consuming roughly 20% of the total current an idling amp draws. The bulb only glows once the power tubes are conducting. The glow is the physical manifestation of the current through the resistance.

    I'd like to hear more about this whole electrolytic capacitor formation thing, because I have seen it too. Computer equipment is produced by the ton or the megaton these days, and I doubt those factories are starting up motherboards and whatnot on a variac.

    Cheers!
     
  10. schmee

    schmee Poster Extraordinaire

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    I wonder if It's Gerald Weber that started the light bulb limiter thing or someone previous?
     
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  11. Axis29

    Axis29 Poster Extraordinaire Ad Free Member

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    https://www.amazon.com/dp/B0001GUE3Q/?tag=tdpri-20

    You're welcome! LOL

    Been using the Fastcap Lefty Righty and the flatback layout tapes professionally for years. They are literally the only tape measures I use. Smart, great features and very affordable!
     
  12. Andy B

    Andy B Tele-Afflicted Gold Supporter

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    I made one from a bicycle cone wrench. Hand filed it out to the right size.
     
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  13. Andy B

    Andy B Tele-Afflicted Gold Supporter

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    I use a variac to keep a constant 120VAC on the outlet on my light bulb limiter which is where the amp I am servicing is plugged in to.
     
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  14. Bendyha

    Bendyha Tele-Afflicted Silver Supporter

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    From - National Radio News - 1936 / 08 /09. So as you can see, the idea has been around a while.

    upload_2019-7-9_23-1-21.png upload_2019-7-9_23-2-18.png
    ............................................................................................ upload_2019-7-9_23-2-54.png
     
    Last edited: Jul 9, 2019
  15. Jerry_Mountains

    Jerry_Mountains Tele-Meister

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    The best tool for my amp it's a transport cart, the son of a gun its heavy (Vox AC15)
     
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  16. BobbyZ

    BobbyZ Doctor of Teleocity

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    Light bulb in series with the AC cord is nothing new, I've seen it in old repair books from the 40s and 50s. Well now that updated the page there's the post from @Bendyha with the article from 1936.
    Very handy and easy (or can be completed) thing to make.
    Got an amp blowing fuses? Instead of going through a bunch if fuses trying to figure out the issue the LBL takes the "heat" off the fuse until you figure it out. Then you can pull tubes and see if one is shorted, then pull secondary wires off the power transformer. Get all the secondary wires off and the lights still full bright you most likely need a new PT. Only other possibility at that point is a short on the primary side. (I'm not often that lucky) I use the LBL way more than my veriac.
    As far as charging caps like the Weber book suggests, I don't bother. If you want to do that and the amp has a tube rectifier, you'll want to use diodes. That rectifier tube won't pass anything until you get up to a certain voltage, maybe 80 or 90 volts and I think he says start at 10 or 20. You gotta get somewhere close to 5 volts on the heater filaments to get the tube warmed up to work.
    And yeah, I don't believe Leo Fender put a whole days production of amps on veriacs every night.
     
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  17. King Fan

    King Fan Friend of Leo's Ad Free Member

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    Good stuff y'all about why the light bulb limiter is a great tool.

    I'm sorry to see Mission seems to be gone -- Bruce was always providing good info on amp forums when I started out.

    But I have their lamp tool. It's OK -- still a bit fidgety to get in place and then turn. Not their fault, of course, RIP Mission. The jaws measure just over .81" in my calipers -- what is that, 13/16? Working a cone wrench into shape is a good idea.

    While I was checking on that, I came across *another* great little tool, the deburring tool. Here's the foursome:

    IMG_2439.jpeg
     
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  18. SacDAve

    SacDAve Poster Extraordinaire

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    Yes the pencil reamer is a great tool
     
  19. keithb7

    keithb7 Friend of Leo's

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    I have posted this before...I think it's worth sharing again with our new members. I see King Fan ordered the exact same pair as mine. These are real nice to have in your arsenal. Not expensive either. E-bay will present several options:

     
  20. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    I have several of the same Crafstman 1/4" socket driver handles, one at least with the female drive in the handle.

    But one I remembered that's a huge help and I don';t think has been mentioned is a solder sucker.
    Spring loaded plunger with ceramic parts that solder won't stick to, heat up the old glob and suck it all off with the push of a button.
    Great for former sloppy work, sometimes it's hard to see excess before it drips into tube socket pin holes or grounds switch terminals together.
    Maybe I tend to buy really hacked up amps?
     
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