? on how to use a variac to power on a cr-1040

Discussion in 'Yamaha' started by Chalkboard, Nov 10, 2017.

  1. Chalkboard

    Chalkboard New Member

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    Hi, I have been gifted a cr-1040. The 1040 has been in storage for almost 20 years and in our family since new. It has never had the cover off and doesn't have a mark on it. My goal is to power it on using a variac with the hope of just gently bringing it back up.

    My problem is, I don't know whether to take my time and use small 10v increments spread out over hours, or just get right to it. I have searched and there doesn't seem to be any real consensus.

    My hope is that someone who has first hand experience will be able to offer some suggestions.

    I attached a couple of photos. The 1040 is in its fresh out of storage condition with very little dust.
     

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  2. mbz

    mbz AK Subscriber Subscriber

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    After a long storage I'd be inclined to go with the gradual power up, dunno about waiting hours though.
    More importantly I would be monitoring voltages, bias etc during the variac power up. Maybe
    first 10V, 5-10min then 20V and start monitoring. If you have a dbt then that would be added protection.
     
  3. Chalkboard

    Chalkboard New Member

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    I am leaning towards an incremental power up as you mentioned, but have some more reading to do.

    As much as I wanted to power it on yesterday, I have decided to build a dim bulb tester first just for added precaution. After that, I don't think there is much more I can really do. I am not skilled enough at this point to monitor the biases. So I will have to save that for a later day. I just want to get it up at this point, then decide where to go.

    Another question might be, will the lower voltage early on, adversely affect any circuitry.
     
  4. petehall347

    petehall347 the brandy coffee man

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    should be fine with just dbt .
     
  5. OMGCat!

    OMGCat! AK Subscriber Subscriber

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    Wouldn't be a bad idea to use something like a Killawatt to monitor it while bringing it up though a DBT will tell you much the same thing without numbers.
     
  6. Lavane

    Lavane AK Subscriber Subscriber

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    I have a couple amplifiers that state in the service manuals "do not use a variac". Apparently some SS devices don't like it much. I use a variac for my tube gear, and a dim bulb tester for SS. 20171107_131853.jpg
     
  7. rottalpha

    rottalpha Yamaholic

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    You probably have some v-fet amplifiers such as the first generation Sony.
     
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  8. rottalpha

    rottalpha Yamaholic

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    True.
    I actually prefer to use both (in combination)
    The logic is the DBT will keep the fireworks away and the variac will help keep the big PSU cans from wetting the bed. This is especially prevalent when the "vintage" equipment has not been plugged I n for a while.
     
  9. Chalkboard

    Chalkboard New Member

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    I appreciate all the comments. At this point, I'm in the process of gathering parts for a dim bulb tester. Once assembled, I plan to use it along with the variac. My variac doesn't have an amp meter, so I will have to observe the current through the DBT. I plan to use a schedule of 30v increments, 30, 60, 90, 120, with 10-15 minute stops at each increment.

    After reading Lavane's post, I also took a look at the service manual and can't find any warnings with regards to the use of a variac. The owners manual is still in storage, so I can't check it, though I doubt it would have any mention of a variac.

    I will update when I am ready to power it on.
     
  10. rottalpha

    rottalpha Yamaholic

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    I don't think you have Lavane's "problem" albeit, I bet you would not mind it :D:D (Early Sony V-fet amps should not be powered up by a variac.)


    Your unit would not have that issue....and who needs a stinky manual?
    Here are the instructions: Before you start, take the cover off, have the camera ready to catch the fireworks..and the fire extinguisher on stand-by to put out the house fire :biggrin:

    just kidding, you will be fine.
     
  11. ConradH

    ConradH AK Subscriber Subscriber

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    IMO, if capacitors don't reform in a reasonable amount of time, they'll never be stable. Thus, I wouldn't spend hours and hours. Usually the problems occur for an input voltage of maybe 70 VAC on up. If it were me, I'd monitor current (and also listen to the Variac- you can usually hear if current draw is excessive) and turn the voltage up from zero to 60 VAC over about a minute. Then I'd watch the current and sneak it up slowly 10 VAC at a time every three minutes or so. I'd let it operate normally (most receivers will, if the relay will close) at 100 VAC for longer, maybe ten minutes, and very slowly increase to 110, run for a while, then try for 120. The paranoid would shut it down at that point, give it a good rest, then ease it back up again. Line voltage can be higher, so after a while of that, I'd go for 125. Here's where things get risky. 125 isn't enough margin. I'd want to know the unit could handle brief surges of 130, but let your conscience be your guide. An old unit that hasn't been powered for a long time might not survive that. IMO, some Yamaha receivers (the 620) seemed to have a lot of defective caps, so I don't think you can go wrong with a full recap.
     
  12. avionic

    avionic " Black Knights " Subscriber

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    Boy after going through all this preliminary stuff.. I sure hope the power pack " chip amps" are serviceable.:rolleyes:
     
  13. avionic

    avionic " Black Knights " Subscriber

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    I wouldn't think a DBT or a variac would be good for any VFET or X-power supply.(yamaha)
     
  14. rottalpha

    rottalpha Yamaholic

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    Did you look at the B-2 manual?
     
  15. avionic

    avionic " Black Knights " Subscriber

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    Yeah. Just now. Hmm.I stand corrected.
     
  16. avionic

    avionic " Black Knights " Subscriber

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    Do you have and multimeter ? My fluke will top out around 11A before blowing the fuse inside the meter. More than enough headroom for monitoring your current draw.
     
  17. avionic

    avionic " Black Knights " Subscriber

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    If you draw more than 6A you will blow your mains fuse in the 1040.
     
  18. avionic

    avionic " Black Knights " Subscriber

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    If your unfamiliar with measuring AC or DC current with your meter. Acquire and owners manual for your meter and read over the " How to " before proceeding.:thumbsup:
     
  19. avionic

    avionic " Black Knights " Subscriber

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    If yours is like my flukes. It involves plugging one of the test leads into a special current/amperage jack on your meter. Then manually setting up the meter to read AC amps.Starting at the highest range.
     
  20. Chalkboard

    Chalkboard New Member

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    Are you referring to the parts that can't be sourced any longer?

    What is VFET or X-power?

    B-2 manual? Is that different from the service manual?

    Yes, I have a simple multimeter, and I believe it can measure dc amps, but not ac amps, if that makes sense.

    https://www.homedepot.com/catalog/pdfImages/f9/f9796e88-7980-44d5-a2a3-e0d6ab51630f.pdf
     

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