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Identify filter caps?

Discussion in 'The Workbench' started by Impetus, Oct 14, 2021.

  1. Impetus

    Impetus Member

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    Hi, I'm trying to get an old amp back the way it was and I need to identify these 2 LCR filter caps on top. The 32/16 LCR were a bit shorter than the 50/50 and 32/32 unless I'm mistaken, right? And then the 16 or 16/16 (32) or whatever should be smaller as well, no? So does that leave the possiblity of these only being either 50/50 caps or 32/32 caps? It's not as simple as identifying the rest of the circuit because some of it is wired like a 1987 and other parts are like a jtm50 or I would have an easier time figuring this out I think...sorry, this is the only picture I have, the caps were taken out a long time ago.

    Were the 50/50 and 32/32 caps identical in size with the old LCR's? If they weren't then I guess I know it's not a mix of 50/50 and 32/32 and that they are both the same value at least to narrow it down even more

    The only filter cap I'm sure of is a 32+32 in the preamp but that doenst really help me here..
     

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  2. junk notes

    junk notes Well-Known Member

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  3. Matthews Guitars

    Matthews Guitars Well-Known Member

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    What kind of amp is it? If it's a production model, the schematic is probably available and that will give you the original cap values.

    If it's a customized or custom made amp, contact the builder if you can. He should know.

    Judging by just the corner you bothered to show a photo of, that LOOKS like a 1987 clone. But with so little information to go on, that's just a guess.

    For a 1987, three 50/50uF filter caps would be the norm.

    To make it a bit looser and more like a JTM45, you could drop to 32/32s and see what happens. Go too low and you'll start to get ghosting.
     
  4. StingRay85

    StingRay85 Well-Known Member

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    Ghosting caused by too low filtering?
     
  5. Impetus

    Impetus Member

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    I believe builder has passed away and I said above it's a weird mix of a 1987 and jtm50. 27k on 8 ohm tap like jtm50 and .1 PI coupling but then 2.7k .68 and .0022 on v1b and 500pF/33k too. I promise i would have given more info if I could have. I'm just trying to figure out if I'm right in assuming that those LCR caps could only be either 50/50 or 32/32..I dont have a better picture of the caps and cant get one. I know what the guts are but just trying to figure out those caps on the back since this is all I have to go by


    What I think maybe is that it was a jtm50 black flag and was recapped inside to be like 1987 and even weirder it has 330uF on v2a cathode bypass like eddie mod...but if it was a blackfflag jtm50 then maybe 64 mains and 32/32 screens/PI would kind of make sense but not really the norm for that amp. It has 32+32 preamp. I know the LCR is original but the 1987-ish preamp stuff was done later...that's why I was curious if the 32/16 LCR caps were different size than the 50s and 32s because that would make sense in a black flag but dual 32s also doenst seem too crazy
     
    Last edited: Oct 14, 2021
  6. StingRay85

    StingRay85 Well-Known Member

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    Take a LCR meter and measure?
     
  7. Matthews Guitars

    Matthews Guitars Well-Known Member

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    The caps should be marked. Do you have access to the amp? Can you get the owner to look at the other side of the caps and tell you what the markings are?
     
  8. neikeel

    neikeel Well-Known Member

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    Sorry, but I have to agree with the others - not enough info to go on.
     
  9. TAZIN

    TAZIN Well-Known Member

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    The LCR 32/32 500v caps are shorter than the 50/50 500v but the same diameter.
     
  10. Impetus

    Impetus Member

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    I'm sorry I guess I wasnt clear. Sorry everyone! This picture is all I have to go on to figure out these 2 caps. This amp isnt in my posession and was changed years ago anyways. I have an old picture of the guts but this is the only picture I have of the cap on top
     
  11. Impetus

    Impetus Member

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    Sorry the amp isnt in my possession and was changed years ago anyways. This picture is all I have to figure out the caps on top. I have an old picture of the guts but that doesnt help for this so I didnt post it. Basically I'm just trying to narrow it down because I agree theres not enough info but I was trying to see if these LCR caps could have been something other than 50/50 or 32/32 judging by the size
     
  12. Impetus

    Impetus Member

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    The
    Amp was changed years ago and it's not in my possession anymore. I wish I could contact someone but it wouldn't matter anyway. This picture is all i have for those caps and I was just trying to figure out if they could have been anything other than dual 32 or dual 50 so I could narrow it down
     
  13. Impetus

    Impetus Member

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    How much shorter? I tried looking up dimensions but cant find anything. If you know then I probably could figure it out a little easier
     
  14. TAZIN

    TAZIN Well-Known Member

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    The 32-32uF/500v cap is 2-inches in height by 1.375-inches in diameter.
    The 50-50uF/500v cap is 3-inches in height by 1.375-inches in diameter.

    As far as I can recall the sizes of the LCR caps were something like this:
    16/16 450v are short and 1-inch in diameter.
    32/16 450v, 32/32 450v, 32/32 500v are all the same height (short) & diameter (1.375 inches).
    50/50 500v, 100uF/500v are the same height (tall) & diameter (1.375 inches).
     
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  15. Gutch220

    Gutch220 Well-Known Member

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    If that's ALL you have to go by, and you know they're LCR caps, then I'd guess they were 50/50's. That photo won't give you any more info.
     
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  16. Impetus

    Impetus Member

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    Thank you so much!
     
  17. Impetus

    Impetus Member

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    I'm
    I'm positive they are LCR. Yeah, that's what I'm starting to lean toward too
     
  18. Matthews Guitars

    Matthews Guitars Well-Known Member

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    The shrink wrap blue is definitely LCR. I have yet to personally see any LCRs of that size that were any size other than 50/50. And I've got a box of used ones pulled from many amps. I wouldn't recommend putting them in any amp, but being the cynical miser that I am, I am tempted to list them on ebay 2 at a time and let the bidders determine their value. Sold without any guarantees, of course. (But they do all measure within spec as far as capacitance is concerned.)
     
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  19. Impetus

    Impetus Member

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    Sorry for the late reply. Thanks for the help. I've got ARS and f&t filter caps I'm gonna use...maybe you could clear something up for me... when those aging filter caps like LCr are taken out of an amp and replaced why does it sometimes yield such a difference and sometimes not? If you are hearing a difference then would that suggest the older filter caps were "on their way out", so to speak? Because I've swapped different brands of new caps and no difference or at least not readily obvious but I've also swapped filtering on older amps with new caps and heard a pretty big difference (sometimes) almost as if I upped the filter values rather than an exact swap of the same value.

    I've tried out all 50/50, all 32/32 and even jtm50 BF like 32 main, 32/16 screen/PI and dual 32 in preamp. The amp was definitely 100 mains amd 50/50 pi and screens with 32+32 preamp.

    Is it odd that I experience no ghosting with those low jtm50 filtering values in a 50 watter?
     
  20. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Old caps have higher ESR and leakage, the capacitance may be well off value, and their overall efficiency will be down.

    If the caps are still in good shape when they're replaced, there won't be a big difference in amp performance.

    But if they were just about to explode and spew their electrolyte all over the insides of the amp, the new ones will certainly
    make a big difference. Because they're allowing the power supply to work as it's intended to.

    You'll notice a ride quality difference when you replace tires that are worn to the cords. But if you replace tires that still have
    some tread life left to them, the difference will be less.
     
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