Scavenged transformer question for amp build

Discussion in 'Shock Brother's DIY Amps' started by GhostofJohnToad, Jul 22, 2014.

  1. GhostofJohnToad

    GhostofJohnToad Tele-Afflicted

    Posts:
    1,432
    Joined:
    Nov 10, 2006
    Location:
    Toledo, Ohio
    Been away from the forum for a little while but I'm back and thinking about building an amp. I recently received some old electronic odds and ends that got me thinking... One of which is an old working eiko 460 oscilloscope.
    2014060995181849.jpg
    IMAG0942.jpg
    So I was thinking maybe I could use the transformer from that for a build. And maybe even the case and knobs as it's pretty sweet. So how does one determine the merits of a found transformer and whether it will work? The only thing I see on it are the numbers 30015-3, 9967025.

    I really don't have a preference of what to build yet, but was thinking something well documented like a 5f1, 5e3, etc. Probably build it as a head. I will probably get a partial kit like from Boot hill and mix an match stuff that I have if possible to make it my own I'd love to build something AC flavoured but realize that might out of the realm just yet. Preferably something smaller for at home playing and recording as that's all I do.
     
  2. R. Stratenstein

    R. Stratenstein Doctor of Teleocity Ad Free Member

    Posts:
    15,911
    Joined:
    Aug 3, 2010
    Location:
    Loganville, Ga.
    Sure you want to butcher that nice old 'scope? I've always wanted one, so I could figure out what I needed it for, then learn to use it. :D
     
  3. bparnell57

    bparnell57 Poster Extraordinaire

    Posts:
    5,995
    Joined:
    Feb 10, 2014
    Location:
    Philadelphia, PA
    Getting a tube scope up to snuff is a huuuugge amount of work when you can get used 80's laboratory quality ones for under $100. I have a huge old oscilloscope transformer laying around, and mine is basically 10-15 or so amps of 6.3 volt, and a couple hundred milliamp 120 volt isolation winding. They have the beef to work but they can be tricky to implement. While it's still working, test the voltages, and if they are usable and you wanna disassemble, MARK THE LEADS!!!!! It'll save you hours later on. Also, if you'd like, you could do a fender Greta kind of thing by mounting a speaker in the old display hole, using the knobs and faceplate, and adding extension speaker jacks while using the old chassis and cabinet.
     
  4. printer2

    printer2 Poster Extraordinaire

    Posts:
    6,715
    Joined:
    May 24, 2010
    Location:
    Canada
  5. muchxs

    muchxs Doctor of Teleocity

    Posts:
    13,171
    Joined:
    Aug 14, 2004
    Location:
    New England
    You'll find 2x 5Y3 rectifiers in there. Each rectifier gets its own high voltage windings. One winding is "normal" tube voltage while the other one is something in the order of 1.5kv (1500 volts) for the CRT. It's kinda obvious which section is the high voltage. If I remember correctly there's an oil filled cap... something like 2uf @ 1.5kv as a filter on the high voltage section.

    I have at least two of these old Eico 'scopes in the "Dungeon Annex". The "Maybe Someday" projects go down to the normal Amp Dungeon while the "Probably Never" projects go in deep storage at the Dungeon Annex out in the boonies. Point is if I had one right here I'd poke around in the high voltage and let you know what you're up against. I made a quick search for the 460 schematic and came up with nothing useful.

    The further point is be aware those extra windings have unusually high voltage on them. That's why my old Eico 'scopes are in the "Probably Never" pile. It's not fair to the next unsuspecting amp tech if I build something with a thousand volts lurking on the redundant windings.
     
  6. bdgregory

    bdgregory Tele-Afflicted Silver Supporter

    Posts:
    1,225
    Joined:
    Oct 7, 2008
    Location:
    Virginia
    EDIT: I see MUCHXS replied while I was drafting mine, so much of this may be moot . . . but I left my notes from what I got out of the user manual . . .

    *****************

    I'll be interested to see what you come up with. I had one of these that was working, but not properly, so I scrapped it (wasn't worth even $20 to sell on ebay). There's some good sheet metal, and good handle, some good bakelite knobs, maybe some usable pots, and the transformer. The transformer has 2 separate secondary windings that are very high voltage (~750vac, ~900vac) so these will have to be insulated and tucked. The filament winding should have enough capacity. The main secondary is ~400-0-400vac, which should be usable for something, though it's a little high?

    I have a copy of the full user/service manual is you need it.
     
  7. GhostofJohnToad

    GhostofJohnToad Tele-Afflicted

    Posts:
    1,432
    Joined:
    Nov 10, 2006
    Location:
    Toledo, Ohio
    For the hassle and overkill I think I shall forgo using the transformer then. But there are indeed some good bits on it. Handle is in great condition, knobs, sheet metal, etc.
     
  8. bparnell57

    bparnell57 Poster Extraordinaire

    Posts:
    5,995
    Joined:
    Feb 10, 2014
    Location:
    Philadelphia, PA
    It may not have a high voltage winding, as many of these used flyback transformers to get the highest voltages. It could just be a filament and isolation transformer, like my Knight kit one was. And yeah, cool source for knobs, and don't forget the pilot light.
     
  9. bdgregory

    bdgregory Tele-Afflicted Silver Supporter

    Posts:
    1,225
    Joined:
    Oct 7, 2008
    Location:
    Virginia
    on the contrary, it has multiple (very)high voltage windings, no isolation winding, and possibly only ~4 amps of 6.3V filament.

    oh, yeah - the pilot lamp is good
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.