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Reccomendation for 10uf 160v bias caps

Discussion in 'Let's Talk Vintage' started by boola1, May 24, 2021.

  1. boola1

    boola1 Well-Known Member

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    Hi,

    I need to get a couple for my '69. Any recommendations on brand? I wasn't able to find F&T (so far) which are my usual go to for anything electrolytic.

    Thanks
     
  2. neikeel

    neikeel Well-Known Member

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  3. william vogel

    william vogel Well-Known Member Gold Supporting Member

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  4. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    Nichicon's work just fine, imo.
     
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  5. VladSRB

    VladSRB Member

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    I advise you to try cap from PEG124 series. Kemet makes them. Great capacitor, and will last for a long time
    If you can find them ofcourse
     
  6. PelliX

    PelliX Well-Known Member

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    There's no 'NOS' factor here. A capacitor is a capacitor and has certain technical properties which can be found in its datasheet (or with scope and some probing). Different capacitors will last longer typically, and there will always be those that for some inexplicable reason fail within no time or last seemingly forever. However, it's safe to say that a capacitor should always be as new as possible - it will then spend as much of its life as possible working in your kit.

    Wax/paper: Don't go there. There is better nowadays. They've been out of production AFAIK for quite some time. If you want one as a tone cap, fair enough. When it fails, nothing bad happens, you just replace it. You don't want dodgy caps in 'important' places, though.

    Electrolytic: Don't buy old ones. Get decent new caps. They dry out, full stop.

    Tantalum, ceramic, etc: Well, they generally go on for decades, but I would prefer to pick a fresh one in all use cases, really.

    After all, you wouldn't install a 'NOS HT fuse' in an amp to get better tone, or use a 'NOS power lead', right?
     
  7. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Another vote for NOT buying "NOS" capacitors.

    The best way to extend the life of an electrolytic capacitor: Run it at full rated voltage continuously from the moment it's made.

    The best way to KILL its life: Store it uncharged for an extended period of time. And in a high temperature environment, that's even worse.

    NOS caps that have been stored for 40+ years are very likely to be JUNK, and may have depolarized to the point of being useless.

    The very same electrochemical process that creates the polarization and anodization of the plates is also responsible for that same anodization slowly stripping off the plates when the capacitor is not in use. The electrolyte that allows the anodization to occur is also slightly caustic and will eat that oxide layer, given time.
     
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  8. playloud

    playloud Active Member

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    Do those F&Ts (presuming you mean the 8uf 350V one) fit on the turret board though? I've got a 100uf 350V one here, and it's pretty chunky.

    I've got those same ones (did you get them from "whazzgroover"?) but slightly afraid to put them in the circuit. No issues so far?

    What about Sprague Atoms? Those seem like a popular choice.
     
    Last edited: May 24, 2021
  9. william vogel

    william vogel Well-Known Member Gold Supporting Member

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    I get them from jacobosway_3
    I’ve used them for the past 4 years and never had a problem.
     
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  10. PelliX

    PelliX Well-Known Member

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    Just a friendly reminder that ESR meters are dirtcheap thesedays and very handy when dealing with capacitors. Especially old ones. :thumb:
     
  11. playloud

    playloud Active Member

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    Do you have any recommendations? I've seen new ones for ~US$25 (including free shipping from China), but I don't think I'd trust anymore than I trust the caps as-is. The only tech-approved ones I'm aware of are the "Capacitor Wizards" but they're pricey (for my purposes...)

    I imagine in-circuit testing is a pretty useful feature, if you're going to be testing signal caps in vintage amps.
     
  12. boola1

    boola1 Well-Known Member

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    Thanks for the input everyone. I went for some of these in the end: https://www.mouser.co.uk/ProductDetail/75-30D106M160DC5A

    I'm not a subscriber to NOS electrolytics and not concerned about originality when it comes to them. Mustards - yes, Iskras - yes, Pihers - yes. Electrolytics - scary!
     
  13. neikeel

    neikeel Well-Known Member

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  14. playloud

    playloud Active Member

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    Wow! Who needs a fancy old amp when you have one of those?!!
     
  15. PelliX

    PelliX Well-Known Member

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    I've got a few cheap-ish ones and I've A/B tested them with decent kit - they actually seem surprisingly accurate. Obviously, there's always a bit of margine of error in the measurement, but it will give you a pretty good idea.



    For example, I have a couple of the model pictured on the left. Believe I paid less than 20 Euros for the kit, case and a battery on those.

    Yes. It would be. But it's a lie. Especially for capacitance measurements you really need to remove the component from circuit, simple as that, I'm afraid.

    EDIT: The Peak Electronics Atlas ESR70 I tried was lousy and overpriced. I've been really chuffed with that first type outlined in the video I posted. Plenty of them for cheap on eBay. Identifies all kinds of components and tests them for you, too. It also shows not just the capacitance but also the ESR and estimated voltage loss. I don't use the socket on it too often as I soldered in a couple of alligator clips to the pads below the display, practical for transistors, FETs, etc, etc, though.
     
    Last edited: May 25, 2021
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  16. playloud

    playloud Active Member

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    Yes, I suspected that. Does it only work if there is nothing else in parallel with the cap being tested?

    For a bit of fun, I picked up both of the ones in the video (under US$25 on Aliexpress!) Will also give me something to solder, as the one on the right is a DIY kit...
     
  17. PelliX

    PelliX Well-Known Member

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    Yes, I'm afraid so. I cannot stress enough that in-circuit testing is often quite limited and seems to be 'hyped'. Especially capacitors should be taken out of circuit for any kind of reliable measurement, except for maybe a dead short in an isolated spot.

    Yup, I've also got yet another one that was a kit. The one on the left is my favourite though. Tests all kinds of components, good battery life, auto-off, and if desired, the atmel controller can be reflashed. With that and a decent multimeter I seldom need to get anything else on the bench.
     
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  18. william vogel

    william vogel Well-Known Member Gold Supporting Member

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    Does anyone know what the ESR was in 1969? I don’t think it’s possible. The ones I use are good and they are probably closer to original spec. That’s the reason I recommended them.
     
  19. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    William, in your photo the bias caps look like BC Components? I have used that brand with great success.
     
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  20. PelliX

    PelliX Well-Known Member

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    I'm sure they measured this back then, whether it made the datasheets I'm honestly not sure. I'm a little too young to remember that. I'm not sure what you mean by 'original spec' - components like capacitors drift. A new capacitor bought today will have the same specs as a new one did 50 years ago. Capacitance and so on have not changed conceptually. If a 50 year old capacitor performs differently today, it's because it has drifted and is failing, so it's not original spec, it's degraded spec. If original spec is the target, then buy a new one according to those specifications.
     
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