Sansui QRX 999

Discussion in 'Exclusively Sansui' started by bourvil, Jan 24, 2013.

  1. JOMARK911

    JOMARK911 Super Member

    Messages:
    2,459
    Location:
    Athens Greece
    Thanks bourvil, for sharing, nice but complex machine.
    I will post my c 2301 , nudes, when i get around to clean it.
     
  2. anderslober

    anderslober Yikes...not again!

    Messages:
    3,628
    Location:
    Singapore, Asia.
    Absolutely awesome! :thmbsp:Great work. By far the most complicated beast on the planet!
    When you have restored a couple of 9001's.......you aren't afraid of anything!:thmbsp:
     
  3. bourvil

    bourvil Member

    Messages:
    88
    Location:
    Czech republic
    Thanks for comments to all:thmbsp:. I am glad that you are enjoying this journey with me!:music:

    Today we will look up to the small tone amps behind the bass and treble controls.

    [​IMG]
    This one amp in stock condition. Probably the most densely populated with all orange low leakage caps so there is no more extra space available.
    [​IMG]
    First task was to unsolder all caps, both transistors and all three interconnects which are already bend for shortest way between joints on board. Then good cleaning of board itself but mainly both pots was carried as well.
    [​IMG]
    Here is situation before and after. Two wires are alredy soldered into left board.
    [​IMG]
    TIme to populate the bare board with Nichicons! ES type for low leakage and KW for regular types. Original transistor will be replaced with KSC1845
    and its hFe will be equalised within maximal differnce of 2.
    [​IMG]
    Now all done and boards are ready for whole unit comletation.

    For now this is all and next time we wil be interested in.... wel let me surprise you:banana:
     
  4. naderpe

    naderpe AK Subscriber Subscriber

    Messages:
    771
    Location:
    Chicago
    WOW! You are amazing!
     
  5. harley90

    harley90 Active Member

    Messages:
    353
    Great Work!!! Awesome thread!!
     
  6. bourvil

    bourvil Member

    Messages:
    88
    Location:
    Czech republic
    Ok its time to go further...:music:

    Todays menu is power section. It consists from more boards and each has specific purpose.:scratch2:
    [​IMG]
    This is condition of main power board many months ago. This picture shows original condition - all board is dirty, dusty and covered with thick oily film. Many fuses has stressed filament, so all were replaced alongside with cleaning of fuse holders.
    Restoration includes changing of every capacitor, bunch of diodes and one zener. Because good and reliable source of stable electricity is crucial for function of whole receiver I paid a lot of attention to every part on this board.
    Next was diodes. There was again none failed but 10D1 dodes used here were nasty and their legs were corroded so all were replaced. And finally all transistors were replaced too - again many of them had corroded legs and within same ype there was wide spread of their hFe values.:no:
    [​IMG]
    Main power board is directly connected with terminals for 8 pieces of power output transistor which all were in perfect condition and only maintenance was to replace mica insulator and thermal paste.:yes:
    Other wires lead to protector board which engages relay to switch the speaker output on. Last inteconnect leads to the board which is located underneath transformer. This board deals with thermal protection of power transistors. Surprisingly this board is not noted in any of service material I have - I gues if there was any service manual for QRX 999 only as it seem that this board is used only in this type of amp.:scratch2:
    [​IMG]
    This is main filtration caps with two big rectifying diodes. Quite a big piece, but Sansui engineers make it in such a way so it can be disassembled separately - very usefull feature!
    Amost all caps on main power board were stressed by heat (some glued) but none was completely dried (but majority had lower capacitance than needed) the worse situation was on main filtration caps where capacitance was on 50% of original - this was probably reason why unit loudly popped when turned off.:nono:
    Changing main filtration caps even it is sometimes big struggle to find one with proper diameter and with fact that it is usually the most expansive part is IMHO very crucial to performance of all equipment - you have bad and unstable power source and you have nothing but bad sounding amp even you have nothing but Nichicon FineGold everywhere.
    So if you want to restore any valuable amp - start with power source, especially main caps. My experience is that these big caps drifts in their value end ESR most significantly and value 50% of original is not rare.
    [​IMG]
    This is renovated main power board just before final assemly of receiver. Nice ind shine I would tell. Not mentioned before is replaced relay and all wire interconnect were shortened.
    [​IMG]
    And this is refurbished main filtration block. In this case I was lucky as I found exactly same dimension caps very easily. Even the capacity is same the voltage is doubled. The trickiest issue is that I was not able to find fresh production with solder lugs so I have to deal with much smaller snap-in terminals. Fortunately there was enough place so all went well.

    That is all for now. Next part will continue with other power related boards.:banana:
     
  7. macman007

    macman007 Mcintosh..Made In USA

    Messages:
    1,072
    Location:
    Suburbs, north of Baltimore
    I have a QRX-999. Any idea why the OP didn't finish this thread? It looks like it dates back 4+ years since the last post. My QRX-999 and other components came in original boxes, with all the packaging, information, even the hang tags on the controls and cables from Sansui. I too am looking forward to doing 100% restorations at the level as the OP, as thorough as the one Bourvil began on this thread. I will start another thread when I do. Actually I have 3 QRX receivers, so I will be doing the restoration work myself to all 3 of them plus other components. To go with them, there are 2 Quad 8 track decks that both record, plus 2 Quad open reel decks. I am working on them as I post this reply.Actually the entire system is here, including the 4 matching huge Sansui speakers, the Turntable with its OE Sansui Quad cart, and matching Shibata stylus. I've picked up a couple hundred Quad LP's, QS, SQ and CD-4. plus several boxes of pre recorded discrete 8 track and reel to reel tapes to play in these decks and enjoy I'm hoping to getthe everything restored, back up and running over the next 6 months or so. After I get the first QRX receiver and the rest of the system done, I will move on the the other 2.
     
  8. LBPete

    LBPete Rolling Along Subscriber

    Messages:
    10,922
    Location:
    Long Beach, CA
    I can't speak for the OP but it's a lot of extra work to document a rebuild to this degree. The QRX-9001 is identical to the 999 except for the face plate and knobs. There should be lots of information on rebuilding those available. Try searching for them. When you do start on your rebuild, start a new thread so we don't confuse yours and his.

    Please post the serial numbers of your Sansui gear. Click on the link in my signature block.

    - Pete
     

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