Sansui AU-222 Hissing Noise

[Fitra]

I got a Sansui AU 222 (Recap & Recable) that made Hissing Noise when volume increased but the noise reduced when I set volume to middle. Also when Treble is turn all the way left (counter clockwise) the Hissing Noise is gone.
I suspect some parts in Head Amp section create these noise.
Thanks for anyone willing to help in this!

 

[quadmatrix82]

The au-222 isn’t the most quiet amp you can replace all the 2sc871 transistors these often go noisy with ksc1845

It’s also advisable to use shorting rca plugs for the phono and tape inputs when not in use

Lovely amplifier enjoy it

 

[Scott Muni]

My AU222 is quiet, but all signal transistors have been replaced.
Be sure to use the tape loop input (not tape head). Aux input goes through the phono amp section for some silly reason.

 

[Fitra]

The au-222 isn’t the most quiet amp you can replace all the 2sc871 transistors these often go noisy with ksc1845

It’s also advisable to use shorting rca plugs for the phono and tape inputs when not in use

Lovely amplifier enjoy it

Thanks, I will try to replace those transistor.

My AU222 is quiet, but all signal transistors have been replaced.
Be sure to use the tape loop input (not tape head). Aux input goes through the phono amp section for some silly reason.

Oh, thanks for the info. I use DAC dongle (usually for IEM) which input should I use?
I forgot to add that even without input (No RCA connected) the Hissing Noise still exist

 

[Scott Muni]

Thanks, I will try to replace those transistor.

Oh, thanks for the info. I use DAC dongle (usually for IEM) which input should I use?

Tape loop, the one with the switch next to stereo/mono switch.

 

[Hyperion]

Be sure to use the tape loop input (not tape head). Aux input goes through the phono amp section for some silly reason.

Cost cutting. - uses the phono stage gain to buffer or improve the sensitivity of the AUX input in this BOTL amplifier.

 

[Fitra]

Do I need to change the phono Amp transistor for less noise? 2SC871F and 2SC733 (originally)

 

[Fitra]

The au-222 isn’t the most quiet amp you can replace all the 2sc871 transistors these often go noisy with ksc1845

It’s also advisable to use shorting rca plugs for the phono and tape inputs when not in use

Lovely amplifier enjoy it

Can I replace the 2SC871 and 2SC871F (in phono amp) with KSC1845FTA? and 2SC733 in phono amp with KSC1815YTA?
i can get them from same (online) store

 

[quadmatrix82]

Can I replace the 2SC871 and 2SC871F (in phono amp) with KSC1845FTA? and 2SC733 in phono amp with KSC1815YTA?
i can get them from same (online) store

i normally buy from mouser or digi key you can get ksc1845 and ksc733 from them in the one order hope that helps

 

[Fitra]

i normally buy from mouser or digi key you can get ksc1845 and ksc733 from them in the one order hope that helps

I'm from SEA, mouser and digikey are too far and this store also source their transistor from mouser and digikey and sold them at equals to 20 cents each

 

[quadmatrix82]

Those substitutes I believe are ok

 

[Fitra]

Cost cutting. - uses the phono stage gain to buffer or improve the sensitivity of the AUX input in this BOTL amplifier.

I plan to replace all small transistor, are these OK?
Original Transistor, TR601: 2SC871F, TR603: 2SC733, TR701: 2SC871, TR801: 2SC871, TR803: 2SC815, TR805: 2SC815, TR807: 2SA539

 

[rotobadger]

I plan to replace all small transistor, are these OK?
Original Transistor, TR601: 2SC871F, TR603: 2SC733, TR701: 2SC871, TR801: 2SC871, TR803: 2SC815, TR805: 2SC815, TR807: 2SA539

Can you update us as to whether replacing the transistors got rid of your hiss problem?

 

[mr_macgee]

It’s also advisable to use shorting rca plugs for the phono and tape inputs when not in use

Lovely amplifier enjoy it

I totally concur about using shortening plugs on the Tape Head (see pic), it really helped mine quiet down. It's such a simple little beast, just go through everything and check each item down the line, take mesurements, it doesn't take long but be careful, I had a 2SC871 transistor go bad, even though it tested fine on its own, so it was head scratcher for a while, (replaced with KSC1845). Our fellow member Doctorhugo helped me with mine.

Not to mention, copious amounts of repeated Deoxit on all controls really did wonders. The old girl just needs a little attention and freshening up : )

Enjoy the amp, it's my favorite Sansui. along with the matching TU-555 tuner.

 

[quadmatrix82]

I plan to replace all small transistor, are these OK?
Original Transistor, TR601: 2SC871F, TR603: 2SC733, TR701: 2SC871, TR801: 2SC871, TR803: 2SC815, TR805: 2SC815, TR807: 2SA539

Suggest you do the c871 only first, the others are pretty reliable the subs you mentioned look ok if you want to do the lot however

 

[Fitra]

Can you update us as to whether replacing the transistors got rid of your hiss problem?

In the end I only replaced the 2sc871 (with KSC1845FTA) both on Control Amp PCB & Main Amp PCB. Yes it has less Hissing Noise than before.

But now, there's another problem which is potentiometer for balance is problematic and I will try to change it with 100k Ohm for now.

Still, my main amplifier is National SU-7048S which has no audible noise at all

 

[rotobadger]

In the end I only replaced the 2sc871 (with KSC1845FTA) both on Control Amp PCB & Main Amp PCB. Yes it has less Hissing Noise than before.

But now, there's another problem which is potentiometer for balance is problematic and I will try to change it with 100k Ohm for now.

Still, my main amplifier is National SU-7048S which has no audible noise at all

Are you thinking that changing the transistors affected the balance pot? Also, how much less hiss? A lot? Or just slightly reduced? Thanks!