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G-7000 for reconditioning

Discussion in 'Exclusively Sansui' started by Hyperion, Sep 24, 2018.

  1. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Here are the before & after pictures for the G-7000 F-2852 EQ = Phono Amp board.

    Before (below) and After (right)
    IMG_2469a.jpg IMG_2471a.jpg

    Switch has been re-installed, Quality electrolytics installed strategically, Bead diodes replaced, some resistors changed, and other small changes.

    The board is now re-installed, leaving just the speaker terminals, and the main PSU capacitors to attend to, plus a few other small jobs here and there. ;)
     
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  2. kevzep

    kevzep Its all about the Music Subscriber

    I'm starting to replace those green blob caps now, I have found a few bad ones lately......Obviously depends on what it is they are doing in the circuit though..
    Looking good though John, its going to be singing in no time....
     
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  3. sansui88

    sansui88 I'm a Bass Line Junkie

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    Great work John. I keep spotting different things that have been changed on the 2nd picture. Nicely done as well
     
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  4. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Latest progress, the mains cable has been changed for a 3 core round double insulated cable, and the earth core** has been connected to chassis ground. Four 'difficult to get to' electrolytic capacitors hiding behind the rear panel RCA sockets have been changed. The old speaker sockets have been removed and work on mounting the new ones is in progress.

    The replacement bulbs have arrived from AK member Dgwojo (the bulb man ;)), and as soon as the last (backordered - now overdue) capacitors arrive from Mouser I'll be able to post a picture of the completed PSU board, and I'll be able to start re-stuffing the main PSU capacitors.

    One thing I have really noticed during this particular reconditioning is how much faster the power up sequence is now - in other words the 'time to settle'. Before I started the unit was working, but seemed tired, you would power on and everything seemed slower coming to life. Now, I get power light on, signal strength hits 4½, stereo light on, and protection relay closing all in a much shorter time. Also I notice how very much the DC offset and Bias switch on drift has been reduced. It might be my imagination, but it definitely feels like this G-7000 is 'getting ready for some serious cranking'. :D

    **I saw this recently in one of Kevzep's posts, @kevzep and thought what a good idea it was ;)
     
    Last edited: Oct 12, 2018
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  5. ghazzer

    ghazzer Senior Member Subscriber

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    Good observation. Perhaps it is just grateful for your TLC.
     
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  6. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    And now.... Speaker Terminals!

    IMG_2476a.jpg

    You can also see the new mains cable +new strain relief grommet. ;)
     
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  7. sansui88

    sansui88 I'm a Bass Line Junkie

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    Superb work as usual
     
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  8. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    I removed and cleaned the rear heatsink, removed, cleaned and remounted the 4 OP transistors (all original), and reassembled applying fresh heatsink compound. Originally far too much on the rear heatsink, and not enough on the OP transistors. :dunno:

    I also fitted the new dial illumination bulbs to replace the originals which all decided to blow during various testing power ups.

    Here are the old (obsolete) bulbs - past their best I think :D the replacements from Dgwojo fit perfectly and look great. ;) (pictures when the job is complete).

    IMG_2477a.jpg

    The remaining components should arrive from Mouser during the next few days. :thumbsup:
     
    Last edited: Oct 16, 2018
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  9. kevzep

    kevzep Its all about the Music Subscriber

    I think this is essential to be honest, I am now doing it to all the units I am working on these days.....Those frail old power cables are often damaged, and its often surprising how much voltage leaks onto the chassis.
     
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  10. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    This is obviously sparking some interest (pun not intended :D) another bit of good advice from you Kev. :thumbsup:
     
  11. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Here are before and after pictures of the PSU board.

    Before (below) After (right)
    IMG_2465a.jpg IMG_2484a.jpg

    I still need to remove and clean the fuses. ;)
     
    Last edited: Oct 23, 2018
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  12. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Here are some pictures of the Dual Can Main PSU capacitors.

    Original look - just removed.
    IMG_2482a.jpg

    And re-stuffed - with 2 x 10,000µF and 2 x 2,200µF in parallel, to make 2 x 12,200µF
    IMG_2483a.JPG

    There will be a plastic insulator installed over the wiring and some packing to prevent movement. The wires will be fed through small holes behind the three tags and soldered to the original terminals.
     
    Last edited: Oct 23, 2018
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  13. ghazzer

    ghazzer Senior Member Subscriber

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    Nice/neat work. What did you use to carefully cut the top off the can so that it was reusable?

    It is too small for any can opener I have ever seen, so I'm assuming you used a Dremel tool and a good dose of patience.
     
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  14. stereofun

    stereofun Super Member

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    Hi John - splendid work and documentation - which caps did you use to stuff cans with, a 10k and 2.2k must take up some space or are these cans just huge ?
     
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  15. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    I didn't actually cut the top of the can off, all I did was to cut the black plastic covering off just enough to get access to the 'rolled over' edge. Then I carefully prised up the rolled over edge with a screwdriver, (also using 'stubby' snipe nose pliers) the 'edge' will be bent down again to seal the re-stuffed capacitor.
    I don't have a Dremel unfortunately, but yes, a good dose of patience is required to open the cans up, and re-close them. Choice of just the right size screwdriver for this task is crucial, a broad blade and not too sharp. ;)
     
    Last edited: Oct 27, 2018
  16. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    The cans are quite large at 62mm diameter and 80mm long/deep - the 10,000µF (CDE SLPX) are 30mm diameter and just short of 60mm long overall. With 2 of those in the can there is just enough space left to tuck in 2 x 2,200µF 18mm diameter x 40mm long (Nichicon PW) in the remaining space.

    It is pretty tight, you have to place the two 10,000's in the can one at a time, relatively speaking there is 'plenty' of room left for the 2,200's after that though.

    Note: All of this method was copied from a thread by Kale. :bowdown: :thumbsup:
     
    Last edited: Oct 23, 2018
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  17. mattsd

    mattsd AK Subscriber Subscriber

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    I just got a G-7000 to restore myself, so this thread has been very informative. :thumbsup: Just curious, did you replace the soft start relay? I noticed in the after photo it still looks original.
     
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  18. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Well spotted Matt, soft start = no, speaker relay = yes.
     
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  19. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Well, it's nearly finished, I have had it powered on for a couple of hours now, running as cool as a cucumber and sounding fantastic. I'll go over the adjustments again and check everything is as it should be.

    Just need to clean and re-install the front panel, the knobs and the case, also a bit of internal and external cleaning and we are done. I'll post some pictures in due course.
     
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  20. kevzep

    kevzep Its all about the Music Subscriber

    Nice work John, its now better than new!! Excellent!!

    I have a few Sansui's on the go at the moment but I've been a bit slack in putting threads together....Its a lot of work restoring let alone compiling a thread, so good on you for finding the time to share....
     
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