Sansui 210, please explain this...

[Racingh11]

I was checking out a Sansui 210 receiver. It is a single sided power supply with the lower voltage tied to chassis ground. It is rectified into a 1000uF 50V capacitor that shows the negative lead going to ground in the schematic. On the board, the negative lead is not connected to anything, and the board is marked "NC" in the copper next to it. Checking voltage across the cap shows about 5 volts DC. Checking from chassis to positive lead is 45V. From chassis to negative lead is about 0.3V. I'm guessing the impedance of the meter is loading that during testing and giving the results that don't really make sense. Why would anyone have a power cap only connected at one terminal. There is no copper or wires running to the cap on the front side.

 

[Blue Shadow]

Is it only two connections on the cap? If three connections, one is not electrically connected and just used for additional support.

What does the cap have written on it as the pins will be identified.

 

[Racingh11]

Is it only two connections on the cap? If three connections, one is not electrically connected and just used for additional support.

What does the cap have written on it as the pins will be identified.

Of course. lol Wasn't thinking there. I bet it is a three terminal cap.

 

[Racingh11]

It is rated at 8 watts per channel 8 ohm. Tested about .06% THD then went up to about 0.1% after things warmed up.

 

[Racingh11]

 

[Bruno Primas]

It is rated at 8 watts per channel 8 ohm. Tested about .06% THD then went up to about 0.1% after things warmed up.

Power output: 10 watts per channel into 8Ω (stereo)

Frequency response: 25Hz to 30kHz


Total harmonic distortion: 1%


Damping factor: 30

Input sensitivity: 3mV (MM), 180mV (DIN), 180mV (line)

Signal to noise ratio: 65dB (MM), 70dB (line)

Channel separation: 40dB (MM), 45dB (line)

Output: 180mV (line), 30mV (DIN)

Speaker load impedance: 8Ω (minimum)

Semiconductors: 30 x transistors, 1 x FET, 20 x diodes

Dimensions: 435 x 127 x 282mm

Weight: 6.1kg

Year: 1972

 

[gadget73]

sounds like its working close to spec. If this is a single rail supply it should have a "center" adjustment that will set the voltage at the junction of the two output transistors. What I've found to work best is to run it right up to the point where it just starts to clip, and adjust that for symmetrical clipping. It gives the best output power possible. It usually ends up with the mid point a little below 1/2 the supply voltage.

if thats off, it limits output power and considerably increases distortion.

 

[Racingh11]

Power output: 10 watts per channel into 8Ω (stereo)

Frequency response: 25Hz to 30kHz


Total harmonic distortion: 1%


Damping factor: 30

Input sensitivity: 3mV (MM), 180mV (DIN), 180mV (line)

Signal to noise ratio: 65dB (MM), 70dB (line)

Channel separation: 40dB (MM), 45dB (line)

Output: 180mV (line), 30mV (DIN)

Speaker load impedance: 8Ω (minimum)

Semiconductors: 30 x transistors, 1 x FET, 20 x diodes

Dimensions: 435 x 127 x 282mm

Weight: 6.1kg

Year: 1972

The sheet for the 210S says 8w 8 ohm and 10w 4 ohm, and it runs the same voltage as the 210A, so I assume they are the same power.

 

[Bruno Primas]

This is from the Sansui 210 service manual.

 

[Racingh11]

I have gained more power than this thing produces, by changing the power cord on amps. lol