New caps and tubes!

Discussion in 'Marshall Amps' started by John Finnerty, Nov 12, 2019.

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  1. John Finnerty

    John Finnerty Member

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    I have a 1973 100w PTP head.
    Have had it for about 8 years.
    Hated it from the moment it arrived at my door.
    Kinda stuck it in the corner and forgot about it, figured "it's"collectible" leave it as is.
    Took it out every now and then to see if I could develop a relationship with it, but nope.
    So, finally I decided it was time to go.
    Took it to Billy Penn @ 300 guitars to be checked out, cleaned bias check......etc. just to be sure it was A-OK for its future home.
    So after bringing it in to the shop, he suggested I try new caps,tubes,etc.
    Removed a .68uf cathode bypass resistor some one had bastardized it with.
    He was very confident I would reconsider selling it.
    So, OK, go for it!
    Returns home after a week or so and.......
    Holy shit, it's the voice of God!

    Point of all this being change those caps!
    If you intend to actually play your old amp
    Never had one all freshened up before.
    It really makes a huge difference!
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Welcome to the forum John Finnerty :cheers:.
     
  3. Gutch220

    Gutch220 Well-Known Member

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    so is it still for sale?

    I'll give you $1,000,000
     
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  4. John Finnerty

    John Finnerty Member

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    :hmm:
     
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  5. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Lemme get my checkbook...
     
  6. scozz

    scozz Well-Known Member

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    Are you referring to a 1973 1959HW 100 watt head?
     
  7. John Finnerty

    John Finnerty Member

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    $(KGrHqJHJBQFDs+3heDLBQ+g,RN4)Q~~60_57.JPG $(KGrHqF,!rUFDfr5UGZVBQ+gmvKY6w~~60_57.JPG
     
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  8. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Ooh, that one has green filter caps. I've been looking to get the date range those were made in.

    Can you please take a good look at those caps and either make a photo of the labels on them or tell me what they say? There's a date code on them,
    which is a four digit number. Something like 2373, which would be 23rd week of 1973. Or maybe it' s 7323, same meaning but reverse date/week order.


    I'm trying to identify when the green caps were made.

    Oh...it's definite that those caps should be replaced. They've outlived their rated service life with years to spare. If they were tires they'd be on the cords, tread long worn off completely. They're going to fail sooner or later and probably are already not doing their job well due to age related deterioration.

    Should they fail in the wrong way, it's going to cost you a power transformer. Get them replaced. SOON. As in, before you use the amp again.
     
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  9. John Finnerty

    John Finnerty Member

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    All been replaced. Those photos are from when I bought it.
    I;ll get pics of the parts after work.
    I can say the amp was born on Jan. 23 1973.
     
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  10. neikeel

    neikeel Well-Known Member

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    The caps were made by Plessey. Typical 73.
     
  11. Im247frogs

    Im247frogs Well-Known Member

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    Location:
    Brooklyn, Joey!
    There must have been something wrong, because how often do you hear, "yeah I have a 100 Watt Mashall from 73 and I hate it"???
     
  12. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member

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    I have never in my life heard that ..
     
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  13. John Finnerty

    John Finnerty Member

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    :rofl::rofl::rofl::rofl:
     
  14. John Finnerty

    John Finnerty Member

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    Hello,
    can't take a good pic so here is the codes.
    439/1/23502/174
    72 40
    Hope it helps!
     
  15. Matthews Guitars

    Matthews Guitars Well-Known Member

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    72 40. 40th week of 1972. Thanks!

    In '73 and beyond the caps were blue. Come to think of it the last time I saw green caps, the amp was earlier than a '73. So that sort of established an upper date range.
     
  16. John Finnerty

    John Finnerty Member

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    My 73 50w has the blue caps.... 100w is date coded Jan 23 73.
     
  17. Matthews Guitars

    Matthews Guitars Well-Known Member

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    The blue caps also come in black and yellow print versions. The only thing consistent about old Marshalls is that nothing ever stayed the same for very long.

    The yellow printed caps were printed on the blue heatshrink. The black print versions had a label applied UNDER the heatshrink, eliminating the need to print on the heatshrink.

    And this is ODD....I Googled for images of many vintage Marshall chassis, and if the chassis features blue label Daly capacitors with yellow print, then the date code line is always exactly the same: J4 75/28 BTD

    In fact, it looks like ALL of them have identical labels. Every character is the same. I'm suspicious that Daly may have just chosen to print cap labels ONCE,
    in one lot with all the same date codes. If you have a blue label yellow printed 50/50 cap in your Marshall, and it's date code is NOT 75/28, please take a picture of it and post it. I don't think it exists without a photo!

    I have some black label blue caps I saved from recapping my two, and their date code line reads J4 75/28 BTS. So if that IS the date code, then they were doing both black and yellow print caps at the same time. Bizarre again.
     
    Last edited: Nov 14, 2019
  18. John Finnerty

    John Finnerty Member

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    Amp is being stored at the moment.... can't get to it.
    Sorry :(
     

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