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Amplifier repair courses?

Discussion in 'd.i.y.' started by rescuest3ve, Nov 4, 2019.

  1. david ellwood

    david ellwood Kirabosi Kognoscente

    I use a 2445 and 2465 and prefer them to my old 465.

    the hameg scopes have a nice curve tracer built in which is useful.

    have fun!
  2. Barrymagrec

    Barrymagrec pfm Member

    The 2445 and 2465 are better scopes than the 465 and with more bandwidth, which is rarely useful for audio but they are also more expensive and more difficult to fix - and good luck with finding the horrizontal o/p chip if you need one, which is not that uncommon these days.

    I have a 2465 with a duff EHT unit in my loft which I really ought to get round to looking at some time.....
  3. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    2445 and 2465 were about the last, most sophisticated, and highest spec analogue scopes ever made...
    They were also released on to the second hand market in large quantities by the military but maybe 15 years after the Cossor ones.... it was suddenly possible to get one of these "£4K second hand" scopes for around £450 ish!

    The problem is that as Barry says they are very complicated and full of unobtianium bits.. although basically an analogue scope and CRT they have considerable digital functionality, on screen cursors and info etc...
    I often considered getting one but the thought that any one of a myriad of possible faults could make it into a door stop rather put me off.... It basically doesn't pass "the Jez test" for such things in as much as must be repairable by myself and have no unobtainium bits in it. Even the 465 and more so the 475 have a very few Tek made IC's but they are generally reliable and as these were the worlds most popular scopes and made in humongous quantities spares can be obtained.
    Even the Tek 465 etc are bloody complicated compared to any hi fi gear and have maybe 4 times as much circuitry crammed into them as a complete hi fi system would have but the 2445 and 2465 take the biscuit!

    2215's have an issue with the CRT's and all the ones I had did suffer from this... a broad and fuzzy trace that can't be adjusted fully into focus no matter what you do and which is not due to a worn tube or any fault with the circuitry.
    It's apparently to do with the innards of the CRT being slightly out of alignment after a knock or similar "shock" and because of a rather duff design of the tube innards... The one I have left is used as my living room scope due to this. It's not so bad that they are not perfectly usable for most applications but does mean you can't really spot that slight thickening of the trace that tells you a circuit under test has very slight excess noise or RF oscillation.
    I don't know if ALL 2215's are so afflicted or just early ones and then an updated tube was used in them...Mines a Guernsey made one....
  4. david ellwood

    david ellwood Kirabosi Kognoscente

    I've had both for over a decade without any issues.
    I was a Tele Mech with the REME out of school and grew up on Tek and Marconi stuff.
    I also still have my old Racal 9343 which still gives sterling service.
  5. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I'm a big fan of Marconi test gear and have many items. Also 2 Racal frequency counters...
  6. Barrymagrec

    Barrymagrec pfm Member

    My 2215 doesn`t have this problem but I remember it occurring on some late 465Bs, sometimes within the warranty period, which was handy, given the price of a replacement tube.
  7. toprepairman

    toprepairman pfm Member

    Interesting, I ran a couple of such courses just a few years back, went down very well. Not sure if I'd want to repeat them but may consider it if enough interest. Won't be for at least a year though, as I'm still working on the new house, nearly got all the windows in.
    On another coincidence, I do have going spare a minty 2215 with good tube and minty 2465B. Could be prised out of my hands for due consideration. These have both not had any use at all and I think I've probably got all the manuals for them but I'll have to check that.

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