Help - Problem with SANSUI AU-517 AMP

[Srivatsan Sukumar]

Hi:

I have a Sansui AU-517 integrated amplifier. Here are the Symptoms that I am
seeing:

1. When I turn on the power, I can hear some relay engaging and when it does I
hear a "Ting" and "Scratchy" sound from the right channel.

2. When I turn up the volume past 10 O'clock, the scratching goes away and it
plays normally. Now when I adjust the volume everything (does this eliminate
a bad volume control?) is fine until I power down the AMP. Then the cycle
repeats.

My knowledge on electronics repair is atmost Novice level but I want to fix
this myself. Where should I start looking?

Thanks

Please post your reply or send me e-mail at the above address or
ssuk...@oracle.com

[TERRY DEWICK]

t1sr...@tek.com (Srivatsan Sukumar) writes:

>
-> I have a Sansui AU-517 integrated amplifier. Here are the Symptoms that I am
-> seeing:
->
-> 1. When I turn on the power, I can hear some relay engaging and when it does
-> hear a "Ting" and "Scratchy" sound from the right channel.
->
-> 2. When I turn up the volume past 10 O'clock, the scratching goes away and i
-> plays normally. Now when I adjust the volume everything (does this eliminate
-> a bad volume control?) is fine until I power down the AMP. Then the cycle
-> repeats.

Start with the relay that you hear closing after turn on, it most likley is
dirty. Carefully burnish the contacts, burnishing file preferred or 600 grit
emory paper. When done flush with a cleaner (tuner or contact) to remove any
residual grunge.

Terry

[Mark Kinsler]

>I have a Sansui AU-517 integrated amplifier. Here are the Symptoms that I

am >seeing: > >1. When I turn on the power, I can hear some relay engaging
and when it does I >hear a "Ting" and "Scratchy" sound from the right
channel. > >2. When I turn up the volume past 10 O'clock, the scratching
goes away and it >plays normally. Now when I adjust the volume everything
(does this eliminate >a bad volume control?) is fine until I power down
the AMP. Then the cycle >repeats.

Here's a guess: you've got crud on a contact somewhere between the output
transistors and the speaker terminals. When the amplifier is sleeping at
night, oxide grows on the cruddy contact. When you turn it on, only a
bit of current can get through, and intermittently at that. When you
turn the volume up real high the contact arcs over and makes a little
weld, through which music flows unimpeded. This deteriorates again
whilst the amplifier sleeps.
Get a can of contact cleaner and clean the speaker switches (A, B, A/B
and all that) and the insides of the relay that goes ting. Poke a hole
in its plastic case with a hot soldering iron to get the spray nozzle
in. You might have a bad solder connection in the amplifier or in a
speaker, and it's possible that you've got a bum contact within a power
transistor or IC that you can't fix without replacing the bad part.
Happy hunting.
M Kinsler

[SORENSEN]

In article <t1srivas.1...@tek.com>, t1sr...@tek.com (Srivatsan Sukumar) says:
>
>Hi:

>
>I have a Sansui AU-517 integrated amplifier. Here are the Symptoms that I am
>seeing:
>
>1. When I turn on the power, I can hear some relay engaging and when it does I
>hear a "Ting" and "Scratchy" sound from the right channel.
>
>2. When I turn up the volume past 10 O'clock, the scratching goes away and it
>plays normally. Now when I adjust the volume everything (does this eliminate
>a bad volume control?) is fine until I power down the AMP. Then the cycle
>repeats.
>

>My knowledge on electronics repair is atmost Novice level but I want to fix
>this myself. Where should I start looking?
>
>Thanks
>
>Please post your reply or send me e-mail at the above address or
>ssuk...@oracle.com

Hi,

Here is what happens; when you turn on the amp the relay switches.
The noise that you hear is due to dirt on the relay contacts. When
you turn up the volume you get enough voltage across the relay switch
to "bridge" the dirt. This works as long as the relay stays in the
same position (until you turn it of). I once had the same problem
with a Luxman. One cure is to change the relay, either with an original
Sansui part (could be expensive or difficult to get) or with a standard
relay with the same coil voltage and contact current rating. You can
measure the coil voltage when the amp is turned on, the contact
current rating should be a 1-2 amps. A second, cheaper and simpler,
cure is to shortcircuit the relay contacts. This might cause some noise
when the amp is turned on and off (which is why the relay is there
in the first place). However, this solution was proposed by the Luxman
dealer in Denmark, and it worked just fine.
If you are too 'novice' to follow these suggestions, don't repair it
yourself.

Peter

[Mark Kinsler]

>current rating should be a 1-2 amps. A second, cheaper and simpler,
>cure is to shortcircuit the relay contacts. This might cause some noise
>when the amp is turned on and off (which is why the relay is there
>in the first place). However, this solution was proposed by the Luxman
>dealer in Denmark, and it worked just fine.

Not a good idea. The relay is there to protect the speakers from the DC
that's always present at the amplifier output when the amplifier is
turned on. There's a circuit that detects when the amplifier has
balanced (it takes a couple of seconds) and energizes the relay
coil. If a power transistor fails, the amplifier will unbalance and the
relay will cut off the speakers.
If you short out the relay you have the opportunity to connect one side
or the other of the power supply directly across the speaker terminals
while the amplifier is initializing. This will typically burn out the
voice coil of the speaker. The Luxman dealer was lucky: the amplifiers he
tried this kludge on must have stayed in balance pretty well when power
was applied.
M Kinsler

[Sam Goldwasser]

I agree. This may work in some cases but depending on the design of the
amp and the particular sample, it could be an expensive way of saving money.
If you don't want to be gouged by the price of an original replacement
relay, electrical equivalents should be readily available requiring at most
some creative mounting.

--- sam

> M Kinsler

[Kevin Deal]

If you have a service or owners manual for this curve tracer, I will pay
you for it or a copy - thanks!!!! Kevin

[Srivatsan Sukumar]

In article <SAM.95Ma...@colossus.stdavids.picker.com> s...@colossus.stdavids.picker.com (Sam Goldwasser) writes:
>From: s...@colossus.stdavids.picker.com (Sam Goldwasser)
>Subject: Re: Help - Problem with SANSUI AU-517 AMP
>Date: Sat, 6 May 1995 12:14:27 GMT

>In article <D80rE...@boss.cs.ohiou.edu> kin...@bobcat.ent.ohiou.edu (Mark Kinsler ) writes:

>> >current rating should be a 1-2 amps. A second, cheaper and simpler,
>> >cure is to shortcircuit the relay contacts. This might cause some noise
>> >when the amp is turned on and off (which is why the relay is there
>> >in the first place). However, this solution was proposed by the Luxman
>> >dealer in Denmark, and it worked just fine.

[Snip...]

>I agree. This may work in some cases but depending on the design of the
>amp and the particular sample, it could be an expensive way of saving money.
>If you don't want to be gouged by the price of an original replacement
>relay, electrical equivalents should be readily available requiring at most
>some creative mounting.

>--- sam

>> M Kinsler

I am the original poster. Thanks for all the responses. The problem is solved.

I went to a local electronic parts store and bought some tuner clear and some
gunk remover cans. Opened and with a blower removed all the dust. Cleaned all
circuit boards with the gunk remover. Cleaned Relays/Switches with the tuner
cleaner. Dried all circuit board/switches with a hair dryer. Powered it up and
BINGO no noise. The tuner cleaner really works. No scratchy noise from any of
the switches.

Thanks for all your help/suggestions.

-Sri