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Toshiba SD-3950/60 Swenson mods.

post #1 of 4
Thread Starter 

My Onkyo SACD player quit recently (16 day out of warranty and while I'm building the courage to poop in it and post the video on You-tube) I've been tinkering with a few 3950's and 60's doing the Swenson mods to them. The stock DC crackle has been tamed and reduced significantly with the new capacitors but some remains and I'm wondering (since I see resistors added to some of the mods) if someone with previous 3950/60 modding can suggest some component values uf and volts that might help improve noise reduction even more. I'm feeding them into a Schiit Valhalla and Beyer T70-250's  

post #2 of 4

Wow, have not heard of Vinnie or Swenson modded Toshiba CD players in many years.  I modded a couple 3960's but cannot remember any of the details.  Here is an email I found in my "archives" - sorry if it's no use - go to Lampizators site for additional help...

 

 

Here is a short description of what to do with the capacitors:

 

The instructions for the power supply are ok as per Vinnies description. Just drill two small holes on either side of the C801 and C802 which are flanking the coil T801. Bend the leads of the two big black Panasonic caps 90 degree to the side and insert them trough the holes. They lie flat on top of C801 and C802. One covers the fuse partially, but that should not be a problem. Solder the leads of the new caps to the leads of the caps in place by bending them over to those leads on the solder side.

 

The Audio PCB board: 

 

The first line of cap numbers is correct

C901 was forgotten in the Vinnie mod. I saw on the scope digital stuff on this cap. In my first mod I used a Black Gate here. In my second mod I used the 47uF 10V nonpolarized  cap that was harvested from the C918/C920 location because I was out of BG.  C903 and C905 are smoothing caps for the DAC DC supply. Use BG here.  This all you need to replace with BG if you do the Swenson mod by going from the C912 and C910 location with a good audio coupling cap to the RCA connector direct. More on that below.

 

If you replace the OPAmp you need to use BG in the C912 and C910 location. They couple the signal to the OPAmp. C902 is a smoothing cap for the OPAmp and I would recommend BG here as well 47uF 6.3V.  C918 and C920 couple the signal from the OPA to the RCA connector. They are originally 47uF 10V nonpolarized caps. They should be BG but not 6.3Volt.  I saw the signal on the scope. It rides on 5Volt DC and swings into the area of 8.5Volt. 10Volt parts are a wiser choice here.

 

If you do the Swenson mod You make C901,C903, C905 Black Gates at 6.3Volt.  You take out without replacement C912, C902, C910, C920, C918 and the little yellow caps next to the RCA

outlets. Short out the tiny resistors which have 512 written on their body (one is R909). They are in the trace from the corner of the DAC to the positive side of C912 and C910 on top side of the board. You can leave them in place.  Just solder a very thin wire across the resistor using the tinned ends of each resistor to solder to. You can also take the resistors out and short the pads they leave, but make certain there is no short to adjacent traces and the trace the resistors used to bridge.  Then you can use the positive hole of former C912 and C910 to attach your new audio output cap. The other lead can be threaded into the hole left by the little yellow cap that leads to the RCA connector. Test for continuity first.(the other hole is connected to ground) It’s a good idea to cut the trace that connects to this hole of the yellow cap on the topside of the board. That trace connects to a resistor network and a transistor which do the muting on “no signal” condition. Cut the trace on top of the board very close to the hole twice parallel close and scratch away the copper between the two parallel cuts.  (Stanley knife) Make sure not to cut other adjacent

traces.  The trace that connects this hole to the RCA connector is on the bottom side of the board.

I used a film and foil 4uF 100V cap that I had four of. Sounds wonderful with plenty base.

I modded my second player the Swenson way too in a matter of 3 hours. I knew better this time!

Only difference is that I used the stock 47uF 10V nonpolarized cap in the C901 location.

 

Good luck and have fun! 

post #3 of 4
Thread Starter 

Thanks for your input. It was overall helpful even if the project has not technically gained ground.

 

I've spent the last few days swapping out various harvested and purchased capacitors and have calmed the trashy static crackle down, but I'm left with sound that is less than remarkable (diminished bass and rolled off highs the result).

 Depression failure and general "why am I bothering" flowing like a river when I compare the modded 3960 with stock players of other manufacture; I put one of the players back together like it was, and had my answer= the bass was bold tight and correct, the slight sounds of conductor & orchestra were clear and present, and the highs were criminally pure. The 3950/60 is (for the $25 price) something very special until that trashy load crackle steps in to ruin everything.

 

I'm thinking that shi#y op-amp stage being bypassed is what makes the player so juicy (and terrible)

 

has anyone built a bypass output stage with higher quality op-amps and parts?      

post #4 of 4

I'm afraid if I asked more questions regarding this "DC/load crackle" issue, I would not be able to help anyway.  But I modded two of these, a buddy of mine modded another two, and I never heard any "crackle".  The mods did wonders to the stock box and I lived with it for 2 years but, in the end, the player was a little too much on the bright side to me.  I wondered if there was an inherent issue with your stock unit but I see you have many - strange.

John Swenson is still quite active (and accessible) on AA - worth a try to write him.  Or Vinnie R. http://www.audioasylum.com/audio/digital/messages/81792.html

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