Sansui TU-9900 Restoration and Mods

[Algar_emi]

And the new vibration insulaton feet from E-A-R. They are used by Bel Canto by the way...

 

[Netlist]

Ever thought of making a balanced output?

/Hugo

 

[Algar_emi]

No. The real fast way to do it is to build a phase inverter using an other op-amp. No real gain I guest because it is a single ended signal to start with.

Here all the parts that I uograded. The removed AC cord is on the right. Not too bad

 

[Algar_emi]

I added John Camille's "snubber" circuit after the fuse and before the transformer, see: http://www.fmtunerinfo.com/DIY.html

WARNING: Don't try to install this mod unless you know what you're doing. Sector AC voltages are lethal and you can damage your tuner for good.

I also selected what phase (L or N) give me the lowest AC leakage on the frame. I connected the AC inlet ground to the frame using a 0.47uF capacitor. Now the leakage is less than 0.3Vac.

This is complete my works on this tuner. Time to move to the next project.

 

[Zeljko]

I have done the same job on one TU9900 but I used two OPA 604.
Regards!

 

[Zeljko]

And I putted silver mica capacitors to bypass power-supply (PIN 1 was modified to GROUND).
Regards!

 

[Acoustat]

Hello does anyone have the schematic for this unit?? . I have one of these really great tuners but need schematic for upgrade..















Thanks

Lawrence

 

[htsource]

I just purchased a Sansui TU-9900 myself, would like to know if anyone is willing to mod it for me? I was told by upgrading the op-amp, it makes a good difference. I'm in Ontario, Canada.

Much appreciate your information.

 

[Jaimo]

TU9900 mods

Hello HT Source - I have done many of the mods mentioned here to a Kenwood KT-7500 with fantastic results - I am in Ontario as well...look out for a pm from me

 

[n9ami]

My personal belief is if its working then don't mess with it. I think a lot of this audiophile stuff makes no difference except in your bank account.

 

[drjb]

Hello everyone & I'm nearly finished the restoration of my beloved TU-9900 and have a question remaining. The service manual doesn't clearly indicate how to measure the power supply voltage, what leads to use. If anyone can advise me, would much appreciate it.

Also, I have to thank Algar_emi for providing his detailed information as it served me, a novice, as an ideal guideline!

Thank you!

John

 

[diyralf]

I used my Clio system to do a FFT analysis at 1Khz, 0.5V.

Noise floor is as low as the CLIO system, at -120dBV, not bad

The 60Hz ripple from the supply is at -84dBV. I'll see if by replacing the supply rectifier diodes with soft recovery diodes and upgrading the supply caps, the noise floor and 60 hz peak came be lower. They may come from my signal generator also.

But it seems pretty hard to improve already.

I listen to a strong carrier without modulation and the noise floor is soo low, as the measurement are showing, that is perfect silence.

The noise level is very high. Nowadays -130..-140dB are state of the art.