Sansui AU-3900

[mot on/off]

Hello Everybody!!

I've got the Sansui AU-3900 amplifier, it's 2x22W...
I'm looking for the service manual, because something "strange" happend from my brother !!

Some people sell it on net, but i don't know if any mate got it and can post it please..

Thank a lot !!

😉

 

[Leolabs]

What's the "strange" thing???

 

[mot on/off]

Goodmorning!!

I mean that he didn't take care and he propably sortcut the output of the amplifier!! Since then the loudspeakers "scratch" in low volume..

I wanted to measure the check points to see what's going on inside the amp, so i can change the damaged components

Thanx 🙂

 

[Vidalgo]

mot on/off,
Here you can find schematics for your amp. Not free, but cheap.
Hope it will help.

 

[mot on/off]

Hello,

Thanks Vidalgo, i've got the schematics for the amplifier (schearching a lot at the net) for free.
I found out that if i connect a multimeter (in Volts) at the 2 possitive outputs of the amplifier, red - right & red - left i've got voltage!!

Something is wrong with the output transistors maybe..

 

[Vidalgo]

mot on/off ,
you noted:

the loudspeakers "scratch" in low volume..

Probably, the only reason for it is defective volume control potentiometer, with loosing wiper contact.
You can check it with ohmmeter, connected between wiper pin and ground.
If readings momentary "jumps" while turning, the potentiometer must be replaced. Sometimes cleaning also helps.

 

[anatech]

Hi mot on/off,
You are measuring from ground to the speaker output positive?

I don't have the schematic so here goes some general help.

If your unit has capacitor coupled outputs some DC voltage may be a little leakage that disappears when you hook up a speaker.

If your unit is standard direct coupled (no cap, no transformer), a DC voltage is very harmful to your speakers. Full range or woofers in particular. It doesn't take too many volts to kill a woofer. 4 VDC may be enough for some speakers.

-Chris

 

[mot on/off]

Hello again!😉

If i connect the two possitive (red) outputs of the amplifier wih a multimeter, the volume ay 1~2/10 i've got AC voltage!!!
And disturtion at the tweeter!

Schematics

 

[mot on/off]

The two "+" outputs only! without the ground..

+(Left) -----------> O ]----- multimeter

+ (Right) ---------> O ]---- multimeter

 

[dudu]

Hi
write here u'r E-mail address and i'll send it to u.
Regards
Dudu

 

[mot on/off]

Check your mail mate🙂

Thanks a lot!! 😀 😀

 

[meizhi]

au 3900

please tell me the out power of san sui au 3900

 

[mot on/off]

Hello,

I have the owners manual and it's 2 x 28 Watt

I like it anyway!!

 

[anatech]

Hi mot on/off,
Nothing wrong with low power. There are people out there that listen happily to 1 watt SET tube amps.

Nice looking unit, perfect for the bedroom or office.

-Chris

 

[meizhi]

help

please please

i need a circuit of sansui au4900

thanks

 

[meizhi]

help

i have sansui au3900 and au4900

please mail me a circuit

please please my email is meizhi2003@hotmail.com

thanks

 

[mot on/off]

There it is !!!


😉

 

[mot on/off]

Hi mot on/off,
Nothing wrong with low power. There are people out there that listen happily to 1 watt SET tube amps.

Nice looking unit, perfect for the bedroom or office.

-Chris

Sure!

I like him a lot!

I think that it's a very fair amp!



😉

 

[meizhi]

au4900

yes

that is for 3900

please tell me how to get 4900 service manual

thanks

 

[hersp13]

look like sansui au 1100