• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Leestereo's Restoration & Upgrade of a Sansui AU-517

Leestereo

Leestereo

Super Member
AK member @McDee56's very nice Sansui AU-517 integrated amplifier received a complete restoration and upgrade. Note that due to the shared topology between the AU-517 and the AU-717, this current restoration/upgrade is very similar to the latter's detailed AK thread.

Part 1: Tone Control Circuit Board (F-2673)

On the Tone Control board, a total of 28 components were replaced: the signal path polarized electrolytic capacitors were upgraded to stacked film types, bipolar types or Audio Grade polarized types (emitter by-pass); polyester film types were upgraded to polypropylene types; signal path ceramics were upgrade to C0G types (small blue caps) and the ceramic power supply decoupling capacitors were increased and upgraded to higher capacity film types.

index.php


index.php
 
Last edited:
Register to hide this ad
Part 2: Driver Circuit Boards (F-2721 & F-2722)

On the F-2721 (left channel) and the F-2722 (right channel) Driver boards, a total of 31 components were replaced. The local decoupling capacitors were upgraded to higher capacity low ESR types; the 22V zener diodes were replaced with 2% precision/low noise variants and their noise filters were replaced with higher capacity low ESR types; the Vbe multiplier by-pass capacitor was upgraded to a film type; the signal path polyester film capacitors were upgraded to polypropylene film types; and the trimmers for adjusting the bias current and the DC offset were upgraded to high-stability cermet types. The component damage from the in-famous OEM corrosive glue was minimal (only 1 additional resistor needed replacing); the glue residue was completely removed prior to the installation of replacement components. Note that F-2721 and F-2722 boards and the component complement used in the AU-517 are essentially identical (some resistor values are slightly different) to those in the AU-717.

index.php


index.php


index.php


index.php
 
Last edited:
Part 3: Power Supply & Protector Circuit Board (F-2675)

On the regulated Power Supply & Protection board, a total of 25 components were replaced. All of the DC filtering/polarized electrolytic capacitors were upgraded to low ESR types of increased capacity; the bi-polar capacitors in the protection circuit were replaced with bi-polar high temperature types; the failure prone VD1212 dual diode was replaced with 1N4148 diodes in series; and the output relay was replaced with an equivalent Omron MY2 type. Note that any residue from the infamous corrosive glue was removed from the board prior to the installation of any replacement components.

index.php


index.php


index.php
 
I noticed you replaced the zener's on the driver boards but not on the power board. It doesn't look like either were glue afflicted. I'm just curious about your approach to this, whether you were seeing poor readings, maybe just an upgrade, etc.
 
The zener diodes on the driver board were indeed upgraded to low noise, 2% precision types. IMO, this is a worthwhile upgrade as it does directly impact the sound quality since these zeners regulate the supply for the amplifier front-end, i.e., differential input. Also, unlike the zener diodes on the F-2675 board, which are employed as a voltage reference for the pass transistors, the zener diodes on the driver boards do the "heavy-lifting" and hence may be more prone to damage/failure (the replacements are also rated at 1.3W instead of the 1W rating of the originals).
 
Part 4: Pre-Main Switch Circuit Board (F-2670)

On the Pre-Main board, the electrolytic capacitor pairs were upgraded to WIMA stacked polyester film types.

index.php


index.php




Part 5: Main Power Supply Capacitors and Film By-Pass Capacitors

The stock main power supply capacitors (12,000uF/63V) and their polyester film by-passes (1uF) were upgraded to 15,000uF/63V Kemet capacitors and 2.2uF polypropylene types, respectively.

index.php


index.php


index.php
 
Last edited:
Beautiful work! @McDee56 is going to love it.
Do the upgrades made increase the amplifiers power at all?
Not that 65w is underpowered for most sane applications, I expect it is closer to 75w stock anyway.
Great to see another Sansui restored.
 
Alex22 said:
...Do the upgrades made increase the amplifiers power at all?
Not that 65w is underpowered for most sane applications, I expect it is closer to 75w stock anyway...
Click to expand...

The amplifier power output is constrained by the supply rail voltages (±51VDC in the AU-517), and these cannot be increased without replacing the power transformers. The official power output of 65WPC (8 ohms) is a conservative one; with the OEM power supply the AU-517 should be capable of ~85 watts (8 ohms).
 
Part 6: Equalizer Circuit Board (F-2723)

On the phono stage board, a total of 30 components were replaced. In the signal path, the polyester film input capacitors were upgraded to polypropylene film types; the stock ceramic capacitors in the input low-pass filter were replaced with C0G types; the capacitors in the output high-pass filter were replaced with a single 4.7µF stacked polyester film type and the low end roll-off capacitors for the RIAA equalization, were upgraded to bi-polar types. The local decoupling capacitors were replaced with higher capacity low ESR types; the "speed up" capacitors (C19, C20) were upgraded to Nichicon Audio Grade types. Also, the failure-prone fuse resistors and VD-1212 dual diodes were replaced with metal film resistors and 1N4848 diode pairs, respectively.

index.php


index.php



Note that in some AU-517s, the high-pass input filter consists of electrolytic capacitors (C37/C38) with film by-pass (C01/C02) instead of 1.0uF polyester capacitors. Nevertheless, since the F-2723 board used in the AU-517 is identical to the one in the AU-717, all AU-517 phono stages can be upgraded to 1.0uF polypropylene film input capacitors.

index.php


index.php
 
Alex22 said:
Beautiful work! @McDee56 is going to love it.
Do the upgrades made increase the amplifiers power at all?
Not that 65w is underpowered for most sane applications, I expect it is closer to 75w stock anyway.
Great to see another Sansui restored.
Click to expand...

Oh I love it more than words can explain. I will apologize to @Leestereo via this post for my delay in expressing my great appreciation for his work and just how much I really do love my @Leestereo restored 517. I feel as though my delay in providing my words here has been simply rude and goes completely against the tremendous love I have for magic Ben has put in to my 517. And I mean it when I say magic. Our passion and love for music is why we are all here and personally music is my medicine. It has helped me through some dark times and every single time I turn on my 517 I think of Ben and want to thank him for the extra healing powers he's placed within. This might sound corny but I really do struggle with the right words to say to show both my appreciation in Ben's work and also just how good the amp now sounds. I hear things I have never before on albums I have listened to 100 times over again via other equipment. I could spend some time going over songs I have played on it that simply blew my mind and I am happy to do that should there be a desire. Aja was the first album I played when I got the amp home and hooked up and I remember messaging Ben about a minute in to track two (Aja) letting him know my jaw was on the floor with the quality in sound (and the amp sounded pretty solid prior to Ben's work). I tell my friends the best way to really describe it is a richness that can have a 2 minute long Beatles songs for instance feeling like it's 5 minutes long due to such richness, fullness. I still remember listening to Oh! Darling and thinking this is the first time I've really listened to this song as it's meant to be heard - the bass coming through (Oh!) so cleanly and pronounced. It's like the timing on everything has been dialed in. Now put on some Floyd and the timing of Gilmour's notes coming through with the clarity of the amp can give you goosebumps. There is nobody I would rather want doing any work on my amps after the experience I've had and still am having with my with my restored 517. And the way in which Ben works I'm sure you are all well aware of. @Leestereo thank you for the endless enjoyment to my ears and soul that will last for years to come. The 517 is amongst my most prized possessions.
 
Leestereo said:
AK member @McDee56's very nice Sansui AU-517 integrated amplifier received a complete restoration and upgrade. Note that due to the shared topology between the AU-517 and the AU-717, this current restoration/upgrade is very similar to the latter's detailed AK thread.

Part 1: Tone Control Circuit Board (F-2673)

On the Tone Control board, a total of 28 components were replaced: the signal path polarized electrolytic capacitors were upgraded to stacked film types, bipolar types or Audio Grade polarized types (emitter by-pass); polyester film types were upgraded to polypropylene types; signal path ceramics were upgrade to C0G types (small blue caps) and the ceramic power supply decoupling capacitors were increased and upgraded to higher capacity film types.

index.php


index.php
Click to expand...
Master Lee I see you pulled C19 and C21 from one channel and C20, and C22 from the other channel. What value did you use for the coupling caps C17,and C18. Are jumpers needed in the empty spaces.
Also what values did you use for C15 and C16.
 
On F-2673, in the left channel, the two orange sleeved capacitors (C19/C21) and the adjacent green film capacitor (C17) are effectively a single capacitor: 2 polarized electrolytic capacitors in series (to form a bi-polar equivalent) with a film by-pass. These were replaced with a single WIMA 4.7µF polyester film capacitor (red rectangle) installed at C17; jumpers are not installed at C19/C21. Similarly, a single WIMA stacked film capacitor was installed at C18 for the right channel. The stock 100uF emitter by-pass capacitors at C15/C16 were replaced with Nichicon Audio Grade capacitors of the same capacity.
 
Leestereo said:
On F-2673, in the left channel, the two orange sleeved capacitors (C19/C21) and the adjacent green film capacitor (C17) are effectively a single capacitor: 2 polarized electrolytic capacitors in series (to form a bi-polar equivalent) with a film by-pass. These were replaced with a single WIMA 4.7µF polyester film capacitor (red rectangle) installed at C17; jumpers are not installed at C19/C21. Similarly, a single WIMA stacked film capacitor was installed at C18 for the right channel. The stock 100uF emitter by-pass capacitors at C15/C16 were replaced with Nichicon Audio Grade capacitors of the same capacity.
Click to expand...
:rockon:Love it! Thanks for sharing your knowledge. :bowdown:
 
You must log in or register to reply here.
Back
Top Bottom