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Thread: Tresham DR-102 Power amplifier with no Power Supply...HELP!!!

  1. #21
    Join Date: Feb 2016

    Location: London

    Posts: 876
    I'm Don.

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    Quote Originally Posted by DSJR View Post
    Ignoring personalities - and one in particular - I understand Tresham was sold totally to Tannoy and this included all documentation, drawings and so on. This individual wasn't with Tannoy for very long my dealer-pal tells me and, apart from a generally very good review in one of the 'Choice amp books, Tannoy quietly abandoned production a short while later I understand.

    Maybe it's too much bother for Tannoy for someone to look through old files thirty five years on, but if they hold the schematics and so on, they should be willing to help surely? Maybe they've also destroyed all the old paperwork and designs for units that they didn't continue with?
    Spot on, yes Tannoy's bought the brains as well as the documentation et al.

    about 7 years ago, I came across a DR-1 Tresham pre amp, with no power supply...1st call = Tannoy. I spoke to customer services; Can't help you Sir point blank.
    2nd Call to Schweppes (You know who): totally negative response, didn't want to know, why don't you try one of my plastic boxes with earthing problems?

    There's load more, but this thread is all about re creating a power supply, and whose got the schematics...

  2. #22
    Join Date: Aug 2008

    Location: Suffolk, UK

    Posts: 1,473
    I'm Paul.

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    I also suspect that the published power output of these amps were very conservative. I found a data sheet and the figures seem to be what the designer considered maximum power while still retaining good performance, not what the amp is actually capable of. The key is to find out the output of the low current regulator. For this I think it is a case of tracing out the circuit and running it through a simulator.
    Last edited by Primalsea; 17-11-2017 at 19:38. Reason: I hate typing on tablets!
    ~Paul~

  3. #23
    Join Date: Oct 2011

    Location: Nothamptonshire

    Posts: 164
    I'm Sharif.

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    Not sure if this will help!

    Tresham transformer.jpg

  4. #24
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,089
    I'm Alan.

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    Well that certainly helps a lot.

    With a bit of creative rectification you could do that with 2 off the shelf transformers.

  5. #25
    Join Date: Aug 2008

    Location: Suffolk, UK

    Posts: 1,473
    I'm Paul.

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    I think I may have cracked it.

    Toroidal 35V x 2 300VA RS 123-4029. This is rectified and filtered in the DR102 to provide +/- 50 VDC for the output MOSFETS.

    Toroidal 67V x 2 1A (120VA). This is rectified and filtered in the DR102 to provide +/- 100 VDC which is then dropped to +/- 80 VDC for the driver stage. A 65V X 2 toroidal may work; is is a more commonly available item.

    Toroidal 18V x 2 120VA (3.33A) RS 223-8033
    2A 200V Bridge rectifier RS 629-3728
    2 x 4700uF 50V capacitors RS 711-1526 (Twin pack)

    These last three items are required because the relay and sensing board needs +/ 24VDC. I haven't checked the but this may also be the power supply for the preamp as well. Not sure yet. Very over specified components just to power a relay board.

    From Farnell:

    Connector Housing, Mini Universal MATE-N-LOK Series, Plug, 9 Ways, 4.14 mm
    Manufacturer: AMP - TE CONNECTIVITY
    172169-1

    Connector Housing, Mini Universal MATE-N-LOK Series, Receptacle, 9 Ways, 4.14 mm
    Manufacturer: AMP - TE CONNECTIVITY
    172161-1

    The connector & plug are to replace the BICC Burndy 12 way connectors that are no longer available as far as I can tell. Only 7 pins are actually used, so a 9 way connector will be fine. This is a 14mm x 14mm connector and some modification to the case may be required.

    Rocker Switch, Non Illuminated, DPDT, On-On, Black, Panel, 20 A
    Manufacturer: ARCOLECTRIC
    C1560VQAAA

    Fuse, Cartridge, Slow Blow, 5 A, 250 V, 5mm x 20mm, 0.2" x 0.79", 218 Series
    Manufacturer: LITTELFUSE
    0218005.MXP

    Fuseholder, Base Mount, 250V, 6.3A, 5 x 20mm, Solder Tags
    Manufacturer: BULGIN
    FX0360

    Power Entry Connector, 6600.3, Receptacle, 250 V, 10 A, Panel Mount, Quick Connect
    Manufacturer: SCHURTER
    6600.4320

    LED Panel Mount Indicator, Amber, 240 VAC, 6.4 mm, 1 mA
    Manufacturer: CAMDENBOSS
    IND515205-LED2-T/AMB

    Metal Enclosure, NEMA, IP66, Wall Mount, Steel, IP66, NEMA 4, 12, 200 mm, 300 mm
    Manufacturer: HOFFMAN ENCLOSURES
    MSC20030080E

    the case is white and not exactly a stunner, but it is relatively cheap.
    ~Paul~

  6. #26
    Join Date: Feb 2016

    Location: London

    Posts: 876
    I'm Don.

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    Well done Paul..

    Sent from my ONE A2003 using Tapatalk

  7. #27
    Join Date: May 2008

    Location: A Strangely Isolated Place in Suffolk with Far Away Trains Passing By...

    Posts: 14,535
    I'm David.

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    I do wish you all the best, as I hate to see old decent gear be chucked out because nothing can be done with them. Even the Goodmans Module 90, of which shedloads were sold (and the chassis used in other label music-centres too, the deck mounted on top) wasn't a bad unit when new I recall.
    Tear down these walls; Cut the ties that held me
    Crying out at the top of my voice; Tell me now if you can hear me

  8. #28
    Join Date: Feb 2016

    Location: London

    Posts: 876
    I'm Don.

    Default So near but so far...

    Well, we've come this far...but we are looking at £100 alone in transformers for this power supply...this could be one costly power supply, unless anyone has any ideas or access to cheaper components, Transformers from a trade source maybe? (not sacrificing quality, of course...)

    Comments welcome...

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