Need guidance on capacitors

Discussion in 'DIY' started by Laura Lex, Feb 9, 2018.

  1. Laura Lex

    Laura Lex New Member

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    Hello,
    I am new here.
    I recently bought a second hand Marantz 2226BL receiver dated 1978.

    I would like to change its electrolytic capacitors.
    I checked the components list in the service manual and some of the electrolytic capacitors are marked like: 10uF ± 30 35V or 10uF +100 -10 35V.

    Can you tell me what those ± values mean?
    I have checked some online electronics shops and they don't have the ± values in their components list.

    Also, what brands of capacitors do you recommend?

    Are there any other components that I should change, besides electrolytic capacitors?

    What temperature should I set the solder iron to change the capacitors?

    I am new to electronics DIY so any other tips would be very welcome.

    Thank you.
     

     

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  2. gadget73

    gadget73 junk junkie Subscriber

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    Thats the tolerance, probably in percent. 10uf +/- 30%, and 10uf +100%, -10%.

    Is there a specific problem you're looking to resolve with a re-cap here?
     
  3. Laura Lex

    Laura Lex New Member

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    No, except that the receiver is 40 years old and I heard that it is better to change them as they deteriorate in time.
     
  4. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Correct.. in both cases.. They are referring to the tolerance and the caps are far older than their designed lifespan. Even if they "work" right now, they are not working well and since the lifetime of stress is unknown, you can only guess how much longer they will work. My own 2226B worked for over a year with the original caps. When I took it apart and recapped it plus a few other bits ( certain transistors in the pre-amp), the difference it made in sound quality was pretty amazing. Where it has been muddled, it was now clear. I didn't need to push the volume up as much and I got rid of the dreaded speaker "pop" when the power switch was pushed :) My 2285B on the bench worked for a few days and then a couple of caps failed in the power supply. I don't think the unit had been used in forever based on the dust and dirt build up on the chassis.

    I will say this though.. For giggles I did a complete work up on the two filter caps for the 2226B ( 4700uf at 40 volts).. This was ESR testing and leakage testing. Both passed with flying colors even though they are very old caps. On the other hand, several of the smaller caps scattered throughout the system were out of tolerance by a fair margin.. even though they had not "failed". Even then, most of the small ones I tested were not too bad and would pass leakage tests too ( less than 2ma of leakage at their rated voltage)

    So old they are but they hold up surprisingly well. But do they work well? No, they don't. You can hear it. So it comes down to this in my mind.. I want to use my gear as often as possible and as loud as possible :D So I want the caps to be at their best. If my gear was a shelf queen to be admired and used once in a while, I might think about keeping as original as possible for as long as possible.
     
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  5. Laura Lex

    Laura Lex New Member

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    Thank you for the responses so far.

    So how do I shop for replacement capacitors for my receiver?
    I haven't seen tolerance values in the lists of online shops.

    Do you think a newbie like me is able to do the recap job or should I take it to a technician to do it?
     
  6. Blue Shadow

    Blue Shadow I gotta get me a new title

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    There are hundreds of caps of the 10V 35µF variety and that is just from trusted suppliers. you want trusted suppliers. Mouser, Digikey, Allied, NOT EBAY, those are counterfeit caps.

    Look at your paperwork and compare to what is installed in the unit. Replace with what is in the unit. All you need to replace are the electrolytic caps. Cap choice is wide open. Folks like the Panasonic FM and FC if those are still available and the Nichicon PW and HE. But those are just long life regular caps. Many here want to spend more on Nichicon audio caps or the Elna Silmic II caps hearing they sound better. Many also replace any electrolytics of the 4.7µF and lower with film caps, polypropylene usually. But these are generally higher voltage. Nothing wrong with going up in voltage but don't go down. Replace with the same value µF, though.

    Maybe look around for a cap list for the unit or build one at Mouser. Search the 10uF 35V and pick a brand and a series or put that series in the search with the size. for example 10uF 35V UKL (a low leakage Nichicon cap we use at times) and it brings back what they sell. Be sure to select In Stock and then add what you want to a Project and build the list. Many use a spreadsheet to note cap value, voltage, number, from which board, as well as part numbers and such.

    you can spend hours and hours getting a cap list together.
     
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  7. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    To address if you can do the job, the question is can you solder? Not just melt stuff and make blobs but can you use the iron with a bit of an artist flair and do a clean job of it?

    You will be working in awkward directions unless you pull the boards which is a fair bit of work. I'm a fan of solderwick vs a sucker. I also use a squeeze bottle of kesters no clean flux. You will need a deft touch not to lift a trace or cook something by mistake.

    On the 2226B preamp board, there are some transistors that should be replaced with new versions as the OEM degrade and add noise. There are a couple of diodes on the heatsink that are known problem children and fragile. The pots and switches need a good cleaning with deoxit and personally I add a dose of fader lube

    So it's more than just caps
     
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  8. mbz

    mbz AK Subscriber Subscriber

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    How does the amp sound now, ie, bass, mids, highs, soundstage,,,If the amp sounds great...
    If bass and highs are rolled off then probably needs a recap.
    Suggest doing recap in stages, start with something simple like the power supply, main caps Nichicon KW? Nichicon UPW for other power supply caps.
     
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  9. Laura Lex

    Laura Lex New Member

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    Thank you for the tips, people!

    Is there a way to make sure the caps in the online shops are within the tolerance listed in the manual?
    Or are any capacitors from trusted brands like Panasonic and Nichicon sure to be within the tolerances?

    I made a spreadsheet based on the parts listed in the service manual.
    There are 37 different types. Less if the capacitors listed with different tolerance values or no tolerance values can be the same.

    I have done small soldering work when I was younger, constructing small electronics kits for high school projects. So I think changing capacitors may be doable.
    I will do some training on junk electronic parts that I can find around the house before I tackle my prized receiver.

    Is solder wick more efficient than vacuum pumps?

    Are there any caveats that I should be aware of?

    The amp sounds great to me but I don't know how it is supposed to sound when new so I have no baseline for comparison. And it is from 1978 and have never been serviced, with the exception of the burned front panel light bulbs that have been replaced before I bought it.

    When I bought it and turned on for the first time, after a while It smelled like something burned but I didn't notice anything wrong in the sound and after a few days the smell wasn't so noticeable.
    I thought that maybe it was because it haven't been used for a long time and the heat may have burned some dirt and fluff that had accumulated inside during the years.
    Anyone have a hint of what could have been?
    Any component that I should check?
     
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  10. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    I'd replace the lamps with LEDs to help reduce the load on the PS. It also reduces the heat cooking the plastic shell for the dial bay. The LEDs just snap in. If you buy the caps from a reputable dealer like Mouser or Digikey, there is not a need to check them. Most of the caps will be +- 20%.

    I prefer the wick because getting a vacuum sucker into where I tend to work ( I dont pull the boards unless I have to) is virtually impossible. Besides, when I worked as an ET at Hughes.. all we ever used was wick. The pumps then and now were expensive and I dislike the hand one-shot suckers. The trick with wick is you need a hot iron so that "deft" touch becomes even more important. Its not enough just to get it soft and movable.. you need the solder liquid and that takes heat. If you search here on the site for Marantz 2226B, there are more than a few threads of folks restoring these units..mine included :) Good iron, dikes, needle nose are needed.. I also use a cheap LED flashlight, Hemostats for holding items, DeOxit, The Kesters no clean rosin, good lighting :)

    Someday I might get a nice desoldering station. but it's about a 300 dollar investment to buy used and get a rebuild kit.. so not right now.

    I have a thread here where I posted pictures on how to rebuild vs replacing the power switch. They tended to get pretty grimy on the contacts. The speaker switches tend to be problem children.. cleaning them takes some patience and some DeOxit :)
     
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  11. mbz

    mbz AK Subscriber Subscriber

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    As a general health check, the bias and dc offset should be checked. It's nice to know where these are at.
    The trimmers for bias adjustment are generally cr@p, if the bias is way out then I'd suggest replacing the trimmers with the multiturn types.
    If bias ok then leave as is. For me, using the wick is a waste of time and I prefer the pump. I'll try Mikes tip on the wick next time, thanks.

    37 different types of caps sounds like a high cap count. Generally only the electrolytic caps are replaced. A recap is straight forward as long
    as you are careful, methodical, take hi res pics, note cap orientation before removal etc...

    You should do a visual check for any heat stressed/charred resistors etc... Also check for dry solder joints (goggle for pics)
     
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  12. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    The trick with the work is to make a sandwich as it were. Item to unsolder .. then lay the wick on top of the solder, touching the lead if possible.. then a chisel tip iron on top of the wick near the lead. As the solder melts and flows into the wick, slide the wick back and forth a bit while keeping the iron on it. Don't expect the wick to take it all up in a single pass. Often times it takes two times.. once to get the most.. and then a fast follow up to get the remain bit with fresh wick. You don't need to trim it all the way back either, just a bit of solder in the wick is fine if you are going for that last bit. It's just like welding or soldering.. experience helps a lot and you need some practice. Also the RIGHT wick is critical. Most of the stuff sold today is too skinny for working with vintage gear like this. Find some Quick Braid Size E.. comes in a 25 foot spool. .125 of an inch in width. It's a nice size for most of the vintage gear.. not for the huge puddles on some of the busses. https://www.amazon.com/gp/product/B00AZ7JYIC/
     
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  13. Laura Lex

    Laura Lex New Member

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    Some of the caps are listed on the service manual as ±30 or ±50 or +100 -10
    Are new caps from brand names safe to put as replacement without knowing their tolerance?

    Is liquid flux necessary, besides the one that is inside the solder? I'm not sure if I can find Kester flux in my country.

    Keep the tips coming!
    I really going to need them! :)
     
  14. Blue Shadow

    Blue Shadow I gotta get me a new title

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    Yes, the new caps are fine. Ignore the old tolerance. Caps today are ±20 or ±10% for the electrolytics

    Liquid flux isn't necessary. A good Kester leaded solder 63/37 is just fine in a small enough size to make the work go well.
     
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  15. eiraved

    eiraved AK Subscriber Subscriber

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    What he said is true. Most caps are rated within plus or minus 10% and will be safe to use. Also, as long as you know how to solder, you shouldn't have any issues with Kester solder alone.
     
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  16. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    I disagree about not using liquid flux. When dealing with old and sometimes questionable connections, the liquid flux can make the difference of a good connection vs a marginal connection. The whole point of flux is to clean the connection to allow the solder to get a solid and clean connection. Relying on the tiny bit in the solder is risky. That solder is designed for brand new clean connections.. not 40 year old connections with who knows what plus some corrosion on the leads. What I would recommend is using the newer no clean liquid fluxes that wont turn nasty over time. The old rosin stuff worked well but had to be cleaned off or it could cause problems later on. The military was insistent on this for good reason. Of course, they like using conformal coating which just sucked for any rework :/

    This comes from a supplier of solder

    The liquid flux removes oxidation buildup in copper and solder. The oxidation buildup removal is done by the liquid solder flux to assist the metals during their bonding process. Liquid flux also reduces surface tension which allows the solder to flow more free and evenly along the surface of the application.
     

     

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  17. eiraved

    eiraved AK Subscriber Subscriber

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    If you're doing mainly through-hole soldering with older type components like axial-leaded resistors or capacitors, you will not need extra flux because the rosin-core solder will provide plenty of flux. More solder is used to fill the through-hole barrel and in these cases, you'll see a ring of flux around the solder joint. This comes from a supplier of solder.
     
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  18. Laura Lex

    Laura Lex New Member

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    Thank you, thank you for the great tips!

    I did a search for LED lights for the front panel and I noticed that there are white, off-white and blue ones.
    Which ones should I get for the 2226BL to make it look as original as possible?
     
  19. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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    Many like the off white but I'm partial to the blue :)


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  20. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    This is very good advice. If I could add one point it is that the flux spreads and transfers the heat from your iron to the old solder much quicker and more evenly than working without flux. This reduces the amount of time that one needs to have the iron in contact with the traces and reduces the risk of lifted traces. This is especially true with larger caps, which tend to act as heat sinks and can soak up a lot of heat before the solder starts to melt.

    Cheers,
    James
     
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