Sansui 5050 Restoration /w 2700 PCB

Discussion in 'Exclusively Sansui' started by Sagacious, Oct 5, 2017.

  1. Sagacious

    Sagacious Member

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    Hello all,

    I'm going to begin my first vintage audio restoration on my Sansui 5050. As mentioned in the title it is of the 2700/2701 rectifier/power supply variety. I am by no means an expert but I have done a lot of reading on posts from others about what to change out and what to change it out with. This started with me just wanting to replace the capacitors but then I learned of the dreaded fuse resistors so I'll be replacing those too.

    I've found a replacement capacitor list from another thread on this forum but the post is old and some of the caps are obsolete and I'd like to keep all the "audio" caps of the same brand and series. So, I'd like to ask if anyone can chime in on what highly quality audio caps people are using. here's the thread where i got the capacitor list: http://audiokarma.org/forums/index.php?threads/sansui-5050-recapping-successful.252048/

    also, the problem with this thread is that he has the more common F-2648 board and not the F-2700 so I'm sure my capacitor list would be different from his. Does anyone have a list of capacitor values and fuse resistors values for the F-2700 & F-2701 boards? My 5050 service manual only references the version with the F-2648 board.

    Ideally, I'd like us all to come up with a complete replacement parts list with modern day part numbers. I know that's not likely to happen though. Anyway, this will be ongoing for me in between work and kids. Hopefully some folks can fill in the gaps of info for me and I'll post my progress and part numbers along the way...
     
  2. LBPete

    LBPete Rolling Along Subscriber

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    Sansui made a lot of production changes on this model. It's best to make your own list looking at the values on each cap. Take pictures and draw a diagram of each board outlining the location and polarity of each cap. Nichicon has several lines of "audio grade" caps. Look for those as weil as low esr long life caps. I use mostly KT and PW series.

    Nichicon Caps

    Please post the serial number for the database. Click on the link in my signature block.

    - Pete
     
  3. Sagacious

    Sagacious Member

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    Location:
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    Thanks Pete. After looking at that chart I'm assuming you use the PW series for power supply section? Also, have you tried the KZ series for audio vs the KT? I know the KZ temp rating is only 85C. My original thought was to replace everything with 105C rated caps but if the KZ's series are really that much better than the KT and maybe I don't really need 105C rated audio caps(?) --they might be worth it...?

    I'd like to do this right and not wish I chose a different type later...which includes being clear on why I made my choice. I'm learning on this one--but I'm treating it like I'd treat my 9090DB :D
     
  4. Leestereo

    Leestereo Super Member

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    Consider using stacked polyester film (e.g., Wima MKS2, Kemet R82) or electrolytic bipolar types (e.g., Nichicon ES) in the signal path. In the 5050, the preamp stage board (F-2646) is somewhat crowded, but you can use films for the <1µF capacitors and bipolar types for the 3.3µF capacitors. For the driver boards (F-2647), the small ceramics in the signal path, i.e., C03/04 (low-pass filter) and C11/12 (feedback loop) can also be upgraded to C0G types. For non-signal path duties, low ESR types such as Nichicon PW can be used.

    Also, here is a link to the 5050 service manual with a schematic with the F-2700 and F-2701 boards: http://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Sansui-5050-Service-Manual.pdf
     
    Last edited: Oct 6, 2017
    Sagacious likes this.
  5. LBPete

    LBPete Rolling Along Subscriber

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    The PW caps are high quality, high temp, long life, low esr caps. Exactly what you want in audio systems. You will find that not all values are available for all series. ANY of these caps are much much better than what Sansui used originally and will sound wonderful in any Sansui receiver.

    - Pete
     
  6. Sagacious

    Sagacious Member

    Messages:
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    Location:
    Texas


    Thanks Lee. That's a big help. So...you're certainly not the first person to recommend the WIMA MKS2 film caps. Just to be clear, are you recommending that I use the WIMA's in F-2646 for all non electrolytic capacitors less than 1µF? and Electrolytic for everything equal to & greater than 3.3uF ? Is the Nichicon KZ a good choice?

    for the driver board (F-2647) you recommend upgrading to a C0G type. Have you found a particular brand or series you like to use? I came across these: http://www.mouser.com/ProductDetail...EpiMZZMt3KoXD5rJ2N%2bAl5eebuf1QO%2b6p51bk7ko=
    on C03 & C04 the originals have the capacitance written on them (220pF) but no voltage rating ? so I'm not sure if the above part from Mouser is the right choice...and for C11 & C12 I don't see any significant markings on those to tell me what their specs are.

    I guess part of my problem here is that the service manual only lists some of the parts (??) --or am I missing something ? This is really my biggest problem, if the part doesn't have a label to tell me what it is and it's not shown in the parts list --how do I know what to replace it with? :(

    another thing I'm confused about after reading your restoration thread on the AU-717, you mention replacing original polyester/mylar film type capacitors with polypropylene film types. --but aren't the WIMA MKS2's polyester?
     
  7. Sagacious

    Sagacious Member

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    for instance, none of the capacitors are listed and what about R17, R13, R26, R21, R29, etc?
     

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  8. Leestereo

    Leestereo Super Member

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    Typically, Sansui will not include "common" components in their Service Manual parts listings; one has to rely on the schematic to identify the circuit component types and values and then confirm with the actual part installed. This last part is particularly important as there are many instances where the schematic and/or the parts list was in error. Further, the schematic is useful in elucidating the circuit topology and determining components would benefit from replacement with better parts, e.g., replacing signal path electrolytic capacitors with film or bipolar types.
     
  9. Leestereo

    Leestereo Super Member

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    For F-2646, I recommend replacing the signal path electrolytic capacitors <1µF with film types, i.e., C05/06 is a 0.47µF polarized electrolytic that can be replaced with a film type. The other signal path electrolytic capacitors, i.e., C07/08, C15/16, C21/22 are polarized 3.3µF low leakage ("BRN" notation) electrolytics that can be replaced with Nichicon ES bipolar electrolytic types (due to the limited space on the board).

    For C0G capacitors, I have used Vishay, Kemet and Murata brands, for voltage rating, you can use 50V or 100V. Specifically; for C03/04 on F-2647, I suggest reducing the value to 47pF to eliminate the phase shift within the audible range, e.g., http://www.mouser.com/ProductDetail/Murata-Electronics/RDE5C2A470J0M1H03A. Capacitors C11/12 are 3pF in the schematic and confirmed to be the same in the 5050 that I currently have on the bench.

    Polypropylene film is a better capacitor dielectric than polyester. Currently manufactured polypropylene capacitors are small enough to replace the original vintage polyester film capacitors with.

    Generally, due to capacitor size constraints, one can replace signal path electrolytic capacitors <4.7µF with stacked polyester film types and >4.7µF capacitors with bi-polar electrolytic types; original polyester film types can be upgraded to modern polypropylene types. Sometimes, due to and board space constraints (e.g., F-2646), one is limited to using bi-polar electrolytic replacements for <4.7µF capacitors.
     
  10. Sagacious

    Sagacious Member

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    Location:
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    Thanks Lee! I'm definitely taking notes. much appreciated. I'm going to need to complete the "parts list" for each board. regarding film types, do you have a preferred brand/series for polyprops? for F-2646 C05/06 I was looking at these: http://www.mouser.com/Passive-Compo...znbzsZ1z0wquaZ1z0widhZ1yx4avuZ1yx4atuZ1z0wpn9

    Also out of curiosity, (for electrolytics) why do you recommend the Nichicon ES over the KZ, FG, KW, etc?
     
  11. Leestereo

    Leestereo Super Member

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    Have used Panasonic ECW, Kemet PHE426, WIMA MKP...etc...no real preference. The 0.47µF polypropylene capacitor you have linked to is much too large to fit on the F-2646 board. Generally, polypropylene film capacitors are much larger than polyester film types and such, in most cases an original electrolytic capacitor can only be replaced with a stacked polyester film type due to the available board space. For F-2646 C05/06, this WIMA MKS2 0.47µF/63V capacitor would fit: http://www.mouser.com/ProductDetail/WIMA/MKS2C034701C00JI00

    For signal path capacitors larger than 4.7µF, electrolytic bi-polar types (e.g., Nichicon ES) are preferable over polarized types (e.g., Nichicon KZ, FG, KW). This approach is largely derived from the work of Cyril Bateman examining the impact of capacitors on sound quality: https://linearaudio.nl/cyril-batemans-capacitor-sound-articles. He tested electrolytic capacitors extensively and demonstrated that in AC coupling (i.e., signal path), bipolar electrolytic capacitors have the lowest distortion/noise of all the electrolytic types (even the presence of a polarizing voltage) and that film capacitors are generally lower distortion/noise than electrolytic capacitors of any type.
     

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