Cap replacement questions.

Discussion in 'Shock Brother's DIY Amps' started by Bugeater281, Feb 19, 2020.

  1. Bugeater281

    Bugeater281 Tele-Meister

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    So I’ve had this amp for 4 years. Still needs work, I’ve just been super busy. I’d like to get it going now. I’ve replaced one cap and removed the death cap/upgraded to a grounded plug. I’ll be narrowing the nice voltmeter from work tonight to test most of the remaining caps so I can get a shopping list.

    My major questions are which type of caps would you use? There’s so many opinions On this I figured I’d ask here since I spend quite of bit of time here.

    One of the caps is unique. .068uf-600v. I’ve only found one cap the same size without going nos. And it’s a metal film cap. I know I could go to a higher uf but the next highest I could find was .1uf. Which seems way higher than recommended. 00FAA3B3-D3C0-4364-9E75-F26DF86DC8A1.png

    The other two caps I know need replaced are more standard. .01uf 400v. I was going to replace them with these. 64B89D8C-514F-4F5D-8A36-FADA615912BF.png
    Now I have some electrical experience, but I’m not super well versed in amps. Is it ok to use two different types of caps in an amp? I doubt there would be an issue but I’d like to confirm with more experience people.

    And here pictures of these caps. Pretty sure they may be leaking voltage to the pots.(random scratching noises when adjusting pots, echoing and ghost noises, pot looks good and have been cleaned with deoxit). Ironically it the pots with caps connected to them that make noise.

    2E94E704-524E-4089-A907-936D44199902.jpeg E576B5A0-0FDE-4A05-87D2-0277AAB6293E.jpeg
     
  2. Mr Ridesglide

    Mr Ridesglide Friend of Leo's Silver Supporter

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    Bugeater281 likes this.
  3. Bugeater281

    Bugeater281 Tele-Meister

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    Ya that’s the same one I posted, just a different site. I would like to have at least somewhat matching caps. But I also didn’t want to go with the cheapest of the cheap. Then again I’d also like to not spend 10-15 dollars a piece either.
     
  4. schmee

    schmee Poster Extraordinaire Silver Supporter

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    I like Mallory 150's for general use. Some values are white and some are yellow. I got some of those blue "Next gen" caps lately. Not sure the money is worth it but, not that much at any rate. You likely dont need to replace that blue .068 uf cap though. It's a bit rare to find a bad one of those.

    Clean the jacks, they look a bit dirty.
    What amp is that?
    Get some flux, melting those old solder points can be hard without it.
    Those caps are wired like Hammond did them, wrapped around and soldered, they are not easy to get out of an amp. It will be a bit messy.
    I'd leave all those caps in the amp except any electrolytics. Why change them?
     
    Last edited: Feb 19, 2020
  5. Bugeater281

    Bugeater281 Tele-Meister

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    It’s a 1963 magnatone m10. I’ll test the .068 cap later today. If you look at the .01uf 400v caps they have some bubbles forming on them. So I assumed they are bad. I’ll also test those. And stupid question. By electrolytic caps do you mean the large tin can types? They’re may be some of those down in the power supply. I’ll check those also.
     
  6. schmee

    schmee Poster Extraordinaire Silver Supporter

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    I dont see a bubble but yeah, that big tan/yellow .01 may be electrolytic. Even if not, a good idea to replace those waxy ones, but the Ajax blue caps (like Fender used) and the hard ones are usually good.
    You may not be able to test some caps without removing one end from the solder. So if you get a bad reading, do that to be sure it's accurate.
     
  7. Bugeater281

    Bugeater281 Tele-Meister

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    Looks like there are some bigger caps in the power supply I should test. Haven’t been that far down in the amp for a few years . Didn’t have a guitar. So the amps been sitting.

    CAE34501-DA42-493D-8156-F39610F6E489.png
     
  8. schmee

    schmee Poster Extraordinaire Silver Supporter

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    Definitely replace those power supply caps. I don't know if you'll find 30uf but I know 33 uf are out there and would be fine, as well as 44 uf for the 40's.
     
  9. Bugeater281

    Bugeater281 Tele-Meister

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    I found a photo of the power supply I took. And some other good phots of the internals. It’s an interesting amp . Which caps would you replace for good measure? And btw I did fix the ****ty wiring that’s in this photo.

    80BB9414-2032-4654-B4C7-D29F16D120A4.png DE81E7DD-9DE1-425B-B054-2DB567AB17EC.png C6057178-F64E-432C-88A4-B0B7D6B6DC48.png 1E5D4A08-DE33-4013-BC5D-1844BF15B14E.png
     
  10. Bugeater281

    Bugeater281 Tele-Meister

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    I found a photo of the power supply I took. And some other good phots of the internals. It’s an interesting amp . Which caps would you replace for good measure? And btw I did fix the ****ty wiring that’s in this photo.

    View attachment 684774 View attachment 684775 View attachment 684776 View attachment 684778
     
  11. schmee

    schmee Poster Extraordinaire Silver Supporter

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    I guess in general I would replace any of the ones circled in Red first. Then see how it sounds. Next I might replace those metallic blue coupling caps like the one circled in Green if you think there is an issue. (Those are probably ~ .022 uf?)
    It's likely a ton of those carbon comp resistors are way off, but frankly, I wouldn't go down that rabbit hole yet. Many are off in old Fenders and they still sound good. But after capping if you have a lot of hiss or crackling etc, you may have to go there....
    [​IMG]
     
  12. Bugeater281

    Bugeater281 Tele-Meister

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    These where the ones I was thinking. I actually already replaced one of those blue ones. It had popped. Thanks for the help. A local amp shop is looking up the schematic as we speak and they are piecing togeather a kit for me. May pay a bit more. But at least then I’m supporting a local small business.
    D734377D-D1F2-46FA-ACFB-87B8CB93D889.png
     
  13. schmee

    schmee Poster Extraordinaire Silver Supporter

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    Yeah, just go for those blue metallic ones too then.
     
  14. King Fan

    King Fan Friend of Leo's

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    Complex amp. You've done some careful analysis and research here. Have you figured out which caps are electrolytic? They're almost always polarized, often with + or – or a crimp on one end, in higher values, and may have different symbols on diagrams...

    upload_2020-2-19_11-36-29.jpeg

    They're also the very most likely to dry out and fail and hurt your amp if they do.

    It's more than OK, it's important. You want to think in terms of both cap type and cap *function.* On a 1963 amp, it'd be best and simplest to replace every single e-cap -- filter caps especially, but also bypass caps. Amp safety and sound will benefit. The ceramic discs can often stay (some folks like the old ones). Cardboard and paper caps should definitely go, and the blue aluminum ones should go, as you and @schmee discussed.

    But for coupling caps, many folks would really try to keep the desirable blue molded ones (are there 4 here?), including that .068uF cap, so that would simplify finding its replacement. :)

    I'm not familiar with those sea-green caps on the sockets -- or the white Ajax cap. If in doubt, take 'em out.... A schematic will be helpful.
     
    Last edited: Feb 19, 2020
  15. schmee

    schmee Poster Extraordinaire Silver Supporter

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  16. Bugeater281

    Bugeater281 Tele-Meister

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    This may be a dumb question. But the old can in the bottom has 3 internal caps. However it’s wire running to them. So obviously attaching the wire to one end of a cap and the other to ground is asking for trouble(talk about a bad short). Can I just solder in the new caps between the old + side of the electrolytic can and the ground tabs? Or is there a better way to do that? I can post a photo later,

    I’ll also look and see if I can find a larger Split section cap. Haven’t found one that’s 50 30 30 yet.
     
    Last edited: Feb 19, 2020
  17. Bugeater281

    Bugeater281 Tele-Meister

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    And here the full schematic. C9480E4A-05D9-46D5-96ED-47D405169ECD.png
     
  18. King Fan

    King Fan Friend of Leo's

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    Not sure what you're saying you want to do to the (?) cap can? But the easy way is to get rid of it (or bypass it) and use individual caps wired like the schematic.

    FWIW in order to read it we may need to get that scheme off the phone and save it as a high-res image.
     
  19. Bugeater281

    Bugeater281 Tele-Meister

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    Basically I may have to add a turret of some time. So it can support the weight of the new caps. There 3-5in of wiring going to the cap can. The wires off that cap run 30in from the power supply to the main area. In other words there nowhere to support the new connection.
    D1E5BD89-E3C2-42D1-89A7-B883668A4295.png
    The plain red wire and two red/yellow wires run to the tin cap. I guess I could use heatshrink to protect the hot side of the new caps. But I think turret will be the better way to go.
     
  20. Cruisin Home

    Cruisin Home Tele-Meister

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    My opinion, which is maybe not what you want to hear, is for you to take this to an experienced amp technician. This amp has got a lot going on (reverb, vibrato, stereo inputs, foot switches, tone switches, 8 tubes, etc.) and probably above the new DIYer. Your likely going to hurt yourself and/or the amp in the process.

    yes many of the caps need replacing, maybe jacks too, reverb probably not working, likely tube problems, tired wirewound resistors, without even mentioning speaker quality, transformers etc. Needs a good overhaul.

    if I am wrong about your qualifications or you have someone with experience that can help you, I would replace the obvious caps as was mentioned above. Then see if the amp is running and report back on what is wrong and what is right. basics first: heater voltages and B+ voltages to each section.
     
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