Vintage capacitors and resistors

Discussion in 'Let's Talk Vintage' started by Marcomel79, Aug 11, 2021.

  1. Marcomel79

    Marcomel79 Well-Known Member

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    Hey guys, just got talking to this guy in this second hand site in norway (where i live) and he had a bunch of old capacitors and resistors from the fifties and seventies, from his father military stash. I´ll attach some pictures so maybe somebody can identify them and possibly help to see if they can be used in an amp build or used as tone caps for a guitar. He wants 10 dollars for everything..
    Here is the pic. Thanks in advance folks!
    IMG_5752.jpg
     
  2. VladSRB

    VladSRB Member

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    Cant see values or voltage rating on capacitors, but sure you can use them in builds if values are appropriate
    Resistors are fine (mostly 1 and 2 watts), again, if resistance values suits your needs
    Just be sure to check them before use
     
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  3. Marcomel79

    Marcomel79 Well-Known Member

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    Hey, thanks for chiming in! the pic is a screenshot and quite blurry. here is the link to the site https://www.finn.no/bap/forsale/ad.html?finnkode=143487808. On the red square capacitors i can read 390pf, 47pf and 68pf. Its the ones with the color bands that are a mystery...
     
    Last edited: Aug 11, 2021
  4. junk notes

    junk notes Well-Known Member

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    WIMA chicklet?
     
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  5. junk notes

    junk notes Well-Known Member

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  6. mickeydg5

    mickeydg5 Well-Known Member

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    Its worth $10 if you are going to use them.
     
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  7. Marcomel79

    Marcomel79 Well-Known Member

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    Exactly....
     
    Last edited: Aug 12, 2021
  8. Marcomel79

    Marcomel79 Well-Known Member

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    yes!
     
    Last edited: Aug 12, 2021
  9. Marcomel79

    Marcomel79 Well-Known Member

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    The guy doesnt know anything about electrical components. He just sells a lot of random vintage stuff....but judging by the size, those Allen Bradley resistors must be at least 5W.... he said they are both from the 50's and 70's..
     
  10. Marcomel79

    Marcomel79 Well-Known Member

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    Ok i got some close up photos of some of the capacitors and the values were off except for this one. 86E9ECFC-CC3A-46B2-B42C-1EDEBC955C49.jpeg
    I just built an 18 watt plexi clone and the amp works great except the presence control is very noisy when on 9/10 and somebody suggested to replace the capacitor. Now this is also .1uf but, same as the one that came with the kit although the one i have in now is rated 630V. Can i replace it with this one even though this is rated 400V?
     
    Last edited: Aug 13, 2021
  11. PelliX

    PelliX Well-Known Member

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    The voltage rating of a capacitor should exceed the voltage that it will ever see in circuit by a bit. If that section of the circuit never goes above say ~350V, then sure.

    That said, the resistors are probably worth the money, but I would stay well away from those capacitors for anything else than maybe swapping tone caps in guitars. I've said it before, and I will say it again; capacitors break down over time, especially the older types. There is no NOS-value to an old cap - it's just an old cap. Bit like wanting a NOS fuse for your HT, except that when the fuse fails due to old age (very uncommon, so maybe a poor example) nothing is destroyed except perhaps your performance/recording.

    There's a lot of myth here, and it's amplified (no pun intended) by the fact that people experiment with NOS caps (or just plain old caps) and notice that they differ from their modern counterparts, even though the specs printed on them are identical. That's most often due to the component failing - of course it will perform differently then, after all - it's dying.

    Replacing a new capacitor in an amp for an old one would be like replacing a nice new power cord with an old one where the insulation is already falling off. Why ask for trouble when life, generally, will take care of that in one way or another...? :shrug:

    EDIT: Also, testing a resistor or capacitor is not the same as looking at the rating (or colour code) on it. Resistors are easy to test with a multimeter (within reason), but capacitors require an ESR meter or similar. These are quite affordable nowadays, but even the result of those doesn't include a test at high/full voltage to see how it performs then. If you value the equipment, put in new components. Personally, I generally quickly check even new components before installing them. A brand new but bad resistor cost me half a day of troubleshooting many years ago.
     
    Last edited: Aug 13, 2021
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  12. Marcomel79

    Marcomel79 Well-Known Member

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    Thank you for you input @PelliX! What you are saying is absolutely right.
    We keep chasing the magic of old components when the new ones are just as good. Just different. I just wanted to take the opportunity to ask a question about the present control on my amp. When on 9/10 it makes this intense white noise type sound. Could this be a faulty capacitor thats causing this?

    Marco
     
  13. PelliX

    PelliX Well-Known Member

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    Sure. A capacitor is a capacitor, though. Much like a fuse or a power cord, the construction may be different, but the ESR values and capacitance in Farads have not changed. If you can tell a difference between a 0.1uF cap from 1960 and one from 2020, I'd say one of the two has drifted, and 99% of the time it will be the old one. Put some old caps on an ESR meter and compare the values.

    Yes, certainly possible. If you just built this amp using new components it's unlikely that one of the caps (they're new, right?) is misbehaving, but it can happen. Do you have an ESR meter to test the hypothesis and check the potentially faulty cap? Have you got a schematic for this particular build by any chance?

    Also, any way you could upload a clip demonstrating this 'white noise' phenomenon?
     
    Last edited: Aug 13, 2021
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  14. Marcomel79

    Marcomel79 Well-Known Member

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    i dont own an ESR meter to check if the capacitor has gone bad, but like you said, it can happen.
    Here is the schematic for the amp:https://www.tube-town.net/cms/userfiles/downloads/px18-schem.pdf
    and here is the link to the video i made to document the noise from the presence control. sounds a bit harsher than it actually is...
     
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  15. PelliX

    PelliX Well-Known Member

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    No harm in replacing it of course, but if you do this kind of stuff from time to time, a cheap ESR meter is a good investment.

    https://www.banggood.com/Geekcreit-...ance-Capacitance-ESR-SCR-Meter-p-1311439.html

    At less than a tenner it's a solid investment and those happen to test NPN/PNP transistors and diodes for you, give you ESR and Vloss for caps, forward voltage on diodes, etc. You can get them with a nice enclosure for about 15, too.

    Thanks for the clip. Sounds to me like feedback - you're reducing the negative feedback too much. Looking at the schematic, I'd almost expect one of the resistors (including the variable resistor, aka presence pot) to be off spec. Are you positive that all these have the correct value? But sure, go ahead and swap the cap for a new/known good one.

    Dumb question, maybe, but you don't happen to have a microphonic V1 valve that is picking up vibration or a guitar too close to the cab, etc, right?
     
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  16. Marcomel79

    Marcomel79 Well-Known Member

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    Thank you for the link!! All components are correct value...actually about v1, the tube itself isnt microphonic but three of the wires are. Also at least one wire is microphonic in V2. I tried tapping on all tubes but they dont produce any sound. By the way the amp is actually pretty quiet until the presence pot has reach the end of the run. Also much noisier when patching channels together, but i guess that is to be expected
     
    Last edited: Aug 13, 2021
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  17. PelliX

    PelliX Well-Known Member

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    Eh? You mean, you tap the wire and hear it from the speaker? Double- and triple-check those connections, I think something is wrong here. Maybe a close-up pic of the guts?

    Yup, just how it works.
     
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  18. Marcomel79

    Marcomel79 Well-Known Member

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    yeah.. i forget which wire in V1 is very sensitive to even a slight rub. the amp works just fine and sounds terrific....here some close ups of the guts. moving the wires around with a chopstick doesnt seem to make things better or worse...
    0D63CCC0-2190-4951-93CD-7964B74796E8.jpeg 1F22F249-851E-4FF8-8803-3994A9CE663D.jpeg 86CCE4F9-26AD-4614-9180-2D5961117B35.jpeg 0BC3BABF-A2C7-44E4-8F2C-59756BEFCA3D.jpeg
     
  19. PelliX

    PelliX Well-Known Member

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    Well, I don't see anything obviously wrong or likely to be causing this fault. There's some solderwork on the valve sockets that I would certainly touch up/revisit, though. The cap on the back of the presence pot; that's just soldered to the outside casing, right? I can't quite make it out on the photos.
     
  20. Marcomel79

    Marcomel79 Well-Known Member

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    the presence cap goes from center to left lug and from the left lug to ground. i will try and reflow those socket wires and see if that helps:cool:
    4F58F4E9-FDF6-4B74-A74A-4E3AD43A6865.jpeg
     
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