NAD 7020 Receiver - Worth a full recap?

Discussion in 'Solid State' started by Tim D, Nov 11, 2017.

  1. Tim D

    Tim D AK Subscriber Subscriber

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    I recently picked up a NAD 7020 Receiver. It's functional, but the tuner drifts. I'm under no illusions - it would benefit from a recap, but I'm seeing anecdotal info that says it has upwards of 70-80 caps in it. Gosh that would be daunting. I see there are kits available online for the 3020 (amp only cousin), but cannot find a kit for the 7020. Any thoughts? Maybe focus on Power Supply and tuner and a few other areas?

    With that many caps, I'm guessing I don't want to go with desolder wick or a suction bulb. Would you recommend investment in a desolder station? And yep I know the boards are flimsy and the traces are thin and weak.

    Many years ago I had a 3020 and just loved it. I'm kicking myself for getting rid of it, but I was raising a family and had other priorities at the time. This is my attempt to get back in.
     
  2. ilusndweller

    ilusndweller Addicted Member

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    Im curious if the drifting tuner is fixable. Mine drifts as well, rendering it useless. Impossible to tune in a station.
     
  3. Bob

    Bob Super Member

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    having recap kits available is good- saves you a lot of work. recapping gives the unit another
    20 years of life. but unless there are noise issues, you may not need to recap.

    since the tuner doesn't work you could poke around. I'd find a schematic (hifiengine)
    and look at the tuner section. chances are it's one big fat multi-pin chip that hooks up
    to the antenna and support chips for tuning, then outputs analog signals for audio.

    you might try looking into the support chips since the tuning drifts. ID the chips
    (FM and the support chips) and search the archives around the world. Try the
    German sites (and translate unless you speak/read German). I've had to
    do the same on Chinese sites for a board (of all things) I needed switch
    instructions on.

    probably start non-destructively by using wooden pencil/chopstick and poke around
    those chips and see whether there are changes. Not sure if there's an active
    device that changes with temps. try using a canned duster to cool off - use a
    straw to localize the spray if you don't have a freeze can. and if you are truly
    intensive, maybe re-solder all the joints in that part of the receiver.

    I'm in the midst of 5 NAD units - all different and need to troubleshoot and fix.
     
  4. mbz

    mbz AK Subscriber Subscriber

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    Don't really see the point in buying capacitor kits. Where are the caps sourced
    from? fakes? OK, these people might buy in bulk to get a price discount, but you
    are still paying for their time and postage. Also removes the headache of finding
    caps that fit. Better to buy from reliable source like Mouser, digikey,,, and
    probably get free shipping.

    I think I've recapped 3 x 3020's a 3140 and 2 x 3150, got 4-5 others in the shed.
    Must admit I'm not a big fan. Probably like the 3140 best. Yes, in their day they
    did provide a great sound on a modest budget but in todays vintage market there is
    so much better. I'm finding that the extra $$$$'s can be easily found, it's finding
    the time that's the problem, ie, you don't want to spend your time on just OK amps.
    Find yourself a KA-7100 or yamaha CA-800 (PITA) or a Sansui AU-505 or a ...

    Generally the early NADs are easy to work on, just remove the base plate. The NADs
    are also great to learn on, so if the 7020 is a training exercise then OK, otherwise,
    with the tuner issues I'd be tempted to sell as is, otherwise you would need to sort
    out the tuner issues and recap the power supply as a minimum.

    For desoldering I use a $10- solder pump, a desoldering station is a long term
    investment.

    Apology to the NAD fraternity for the rant, I've tried but they sound just ok.
     
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  5. Tim D

    Tim D AK Subscriber Subscriber

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    Greatings from one of the other Melbournes mbz.

    All good info. Then parts shopping it is. It'll take me a bit of research to find the right diagram and then off to do the recap in sections. I'll start with the PS and the tuner.

    I'll be digging though the diagrams looking for the areas that Bob described.
     
  6. mbz

    mbz AK Subscriber Subscriber

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    Didn't notice the Melbourne tag, think there is another one up in canada.

    My general cap guidlines for an amp like the 7020 are,

    Main filter caps: Nichicon KW
    Power Supply caps: Nichicon PW
    Bipolar PSU: Nichicon EP
    Bipolar Audio path: Nichicon ES
    Audio Path: Elna Silmic II's
    Local power rails: Elna Silmic II's
    Low Noise/leakage caps (orange or pale green or very light blue found in phono or preamp)
    Nichicon KL, some people prefer MKS, still undecided

    Your amp so you are free to choose whatever caps you like

    Download the datasheets from mouse, useful for physical size. Most modern caps are smaller
    however you need to check sizes and maybe leed spacing.

    On solder pumps, mine is like this one from mouser
    801-DP-100

    A bit expensive though, maybe someone can chime in with a better budget suggestion
     
  7. Tim D

    Tim D AK Subscriber Subscriber

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    Hi mbz,

    Yes there are actually a number of other towns with the same name. I recently had a co-worker move from Melbourne Aus to here. I joked that he went a long way to go from one Melbourne to another.
    Thanks for the inputs. That was just what I was looking for. I will be checking out Mouser and DigiKey.
     
  8. leesonic

    leesonic Hold on, here comes the bass. Subscriber

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    You don't need a fancy desolder station to do work on this receiver. All you have to do is heat up the solder on the old caps, pull them out, and then use some desolder braid to clean up the excess solder and find the holes. The boards on these receivers are no more flimsy, and the traces are no thinner or weaker than the Marantz, McIntosh, Pioneer, Sansui and any of the other brands people get goo-goo eyed over on here.

    As for your question, is it worth it? If you're planning on selling it, no. If you're planning on keeping it, then sure. The fact that these sold SO well using cheap capacitors is a tribute to their original design. Upgrade it using some choice caps, and you'll eclipse some of the more esoteric brands mentioned above.

    Lee.
     
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  9. Harryconover

    Harryconover Well-Known Member

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    Is it worth it to recap it yes if you plan on keeping it I recommend doing the power supply power amp preamp in that order I worked on many of this line they all suffered the same problem in that the ones
     
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  10. Harryconover

    Harryconover Well-Known Member

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    Sent fo
    sent for review had been carefully assembled by engineer and were great or production units poor to bad a lot of improvements can be had by good QC and cleaning up solder joints I didn’t menchen tuner because you can’t improve the quality of the signal most of the time the signal is very prosesed and then sent out and has all the problems that has
     
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  11. Tim D

    Tim D AK Subscriber Subscriber

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    So when I go to Mouser I'm going to have to look closely at the dimensions of the replacement caps. Does anyone actually measure the dimensions before ordering? What are you guys using to measure the dimensions? A small ruler, caliper, other?
     
  12. llwhtt

    llwhtt Super Member

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    I use a small 6" rule made by Empire, from Sears, it has metric, inches and decimal. I use it to measure the overall dimensions as well the lead spacing. The lead spacing is very important if you want the caps to fit the board correctly. The Panasonic FC series of capacitors often have two caps with the same electronic value but with different dimensions and lead spacing.

    I have 7020 out on the front counter that I use as my speaker tester. I've pulled the cover several times to make a cap list but then figure I have better things to do and put the cover back on. Maybe some day I'll get enough ambition to go thru it.
     
  13. Tim D

    Tim D AK Subscriber Subscriber

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    Thanks llwhtt. That helps a lot. So I'll get a tiny ruler and move on. :)
     
  14. Tim D

    Tim D AK Subscriber Subscriber

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    Next question... Where can I find the right service manual?

    It seems that the HiFi Man site has a manual for the early version with a single big board, but mine is slightly after the original with the separate daughter boards. Mine has 4 caps in the PS too. The AK library doesn't have it either.
     
  15. leesonic

    leesonic Hold on, here comes the bass. Subscriber

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    I wouldn't even worry about measuring the dimensions of the caps. The new ones are 99% likely to be smaller than the originals, even if you up the value of the main ones to 3300uF. If you find the manual for the one with the separate daughter boards, please upload it here. The one you are referring to with the single board is the earlier version, and the one that caused all the reliability problems and subsequent bad reviews.

    Lee.
     
  16. llwhtt

    llwhtt Super Member

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    The main filter capacitors are in a cluster of four so the dimensions are critical there, can't exceed the stock diameter by much if at all. The lead spacing is always important, at least me.
     
  17. Tim D

    Tim D AK Subscriber Subscriber

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    Thanks Lee,

    I was aware of the difference in the early version (and its' problems) and following version. I found this same info while reading other threads on the 7020. I'm kind of hoping that some kind soul will read my plea and say, "I have the Service Manual you need and I'll scan and upload it for the team." I have to believe that such an animal exists. I've been watching the big auction site and searching the internet and just haven't seen any mention of one.
     
  18. leesonic

    leesonic Hold on, here comes the bass. Subscriber

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    You're welcome. But sometimes YOU have to be the guy that blazes the trail for others. I've bought service manuals for stuff and uploaded them. I've also found out the hard way there are people willing to just use all your information and then give nothing back to the (AK) community in return.
     
  19. Tim D

    Tim D AK Subscriber Subscriber

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    No worries Lee.

    I haven't found a service manual for the second version. I'm more than willing to TOFTT and buy it off the big auction site or wherever, but I haven't seen a hint that anyone has seen one. If I get one I'll share it. Any ideas on where I can search?
     
  20. OMGCat!

    OMGCat! AK Subscriber Subscriber

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    I use a Hakko 472D and would absolutely not ever go back to wasting my time with a pump or desoldering braid. It's pricey as these things go but if you're going to be inside a bunch of units and value your time I wouldn't hesitate. If you look on ebay you should be able to find one for about $100 and the maintenance kit from Hakko is another $100 so for $200 you'll be in desoldering bliss.
    The other weekend I had a board with 25 resistors and two caps pulled down bare in ~3 minutes with perfectly clean solder pads and absolutely no damage to the boards.
     

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