Sansui Au-517 in problems

[Hipocrates]

Hello guys.... I just got an AU-517, this is what's going on...
As an amplifier both channels works, as integraded right channel is dead.

Any pointers?

Thanks a million folks.

Hipo

 

[usedto]

The connect/disconnect switch on the back may be dirty. Common problem. Squirt it with some contact cleaner and work it back and forth a bunch of times.

That should cure the problem.

 

[Hipocrates]

Thank you very much!... I'll do it

UPDATE: Didn't work

 

[jd-audio]

If the connect/disconnect switch (at the rear) is not the problem (it often is), then first try all pots/switches at the front. Especially selector-switch, tape-monitor and balance-switch are suspect. Just work them while playing some music and see if this makes a difference.

No changes? Then there is probably an internal issue.

-John-

 

[Sansui_Boy]

Clean every single switch and pot with deoxit and move it around a lot and do it again a couple of more times i am sure it is the connected/separated switch. it could also be the vd1212 varistors diodes

 

[skippy124]

You can eliminate the connected/separated switch by using a set of jumpers or RCA cables to bypass the switch.

If there is no joy after cleaning the controls, it may be that the power supply to the bad pre amp channel has a problem. As these are a dual mono power supply there are separate supplies for each pre amp, and the power supply can fail due to the corrosive Sansui capacitor glue, or a bad rectifier diode, or other failure. If you have a multimeter and know the basics of using it you can easily check the power supply voltage for each pre amp channel.

Cheers

John

 

[Hipocrates]

Thank you very much folks for the assistance...

I will clean the pots and the switch again.

Just in case, and sorry for my ignorance... how is the switch bypass done?

Thanks again.

 

[slimecity]

Once You've done all the above - if you still have an issue - replace the relay - I had issues with mine and spent ages trying to diagnose the issue - when all I had to do was replace the relay. If the connections in there are bad, it could prevent the relay from "turning on" one channel.

 

[Hipocrates]

Awesome, now I have some work to do, thank you Slimecity

 

[skippy124]

Thank you very much folks for the assistance...

I will clean the pots and the switch again.

Just in case, and sorry for my ignorance... how is the switch bypass done?

Thanks again.

On the rear panel above the connected/separated switch there are the pre out/main in RCA sockets. Connect the Left pre out to the left main in and right pre out to the right main in using RCA cables - this effectively shorts out the switch. If this resolves the problem then the issue is definitely with the switch. My bet is that the problem lies elsewhere.

Cheers

John

 

[Hipocrates]

UPDATE:
Controls and switch cleaned, with jumpers in place right channel is dead... without the jumpers right channel is very very weak.

 

[slimecity]

Ok -do you have another power amplifier lying around that you can use for testing? If you get a music signal, run it into your sansui amplifier, and run some RCA cables from the "pre out" sockets of your sansui amp (to an input on your other amplifier), then use the volume control on your sansui amplifier to control the volume - what do you get? This will narrow down if your issue is in the "pre" or "power" section of your sansui. If you still get only one channel working after doing this test: the problem is in the "pre" section of the sansui. If you get BOTH channels working doing this test, then the problem is in the sansuis' "power" section. Good luck.

 

[Hipocrates]

Thanks guys. Slime, just a quick question... Can be possible that this amplifier have problems in the power section even when works just as an amp (not as integrated).
I tested as power amp, works fine.

Should I start to check the cards? I'm looking right now the F-2675 and seems to be fine.

thanks for your help fellas

 

[anderslober]

If the amps are ok....then you have a preamp problem. I had this problem on a 517 I did recently. It was a tr in the preamp section. I found it with my super-advanced Radioshack signal tracer.
Check the input wiring at the RCA points too. A wire could have come loose. It is most likely a tr in the preamp section........easily serviceable. 2sc1222 and 2sa750 .......I changed all of them.

 

[slimecity]

Yes as anderslober says: if your amplifier works fine just as a "power amp" - ie: the power amplifier modules work OK when you have another sound source connected to the input RCA's for the power amp - then that suggests that both the power amplifier boards and the powersupply board (the F-2675 board you have above) appear to be working OK. You've now narrowed the issue down to what could be the input RCA sockets, the input wires, the selector switches, the connection blocks for the pre-section, the controls themselves, or the preamp board (transistors, diodes), or the wires that feed power to the preamp board. You will need to check and go over all those things. Do you have the same issue on the phono section (only using a real phono source, not a line-level source....)

 

[thattreeguy]

I realize this thread is over 3 years old...but I'm so grateful for it and Audiokarma that I had to express my gratitude. I purchased a AU-517 a few months ago (my first Sansui amp, won't be my last!) and coupled with a Sansui FR 5080 TT and PSB Stratus Bronze speakers I had fallen in love with the Sansui sound. So about a week ago when the right channel went dead I was crushed. Being poor and totally tech. challenged I figured it was hopeless...but then I stumbled upon this thread. Thinking there ain't no way, I stuck a straw from a can of deoxit in to the pre/power amp switch and worked it back & forth about 15 times. Hooked it all back up and to my amazement that sweet Sansui sound is back fully in both channels! THANK YOU AK!

I don't know if anyone will read this, but if so I have a question. If this switch causes problems, would there be any benefit (or problems) with connecting the pre out and power in with rca cables? Could using high quality cables have any improvement on the sound quality?

Hope to hear from someone. Thank you.

Can I get a "hell yeah" for Sansui!

 

[Hipocrates]

Hope to hear from someone. Thank you

Good to see that your unit is working and you are happy.

If this switch causes problems, would there be any benefit (or problems) with connecting the pre out and power in with rca cables?

That will bypass the switch. you can try and see if you like it better, to me sounds the same.

Could using high quality cables have any improvement on the sound quality?

That is a controversial subject that people are too passionate about. To me, CL2 14 AWG speaker wire and just some regular interconnects from monoprice or similar and you will be ok.