Technics SA-410 stopped working today

[jaynews]

I have a 23-year old (try not to laugh) Technics SA-410 receiver. It worked
fine earlier today, but I went to use it a 2nd time and I'm getting
absolutely no output out of either speakers or headphones. Something
defitely failed within the unit.

It appears to power up. When booting up it has an orange indicator on the
front says "preload" and then after a few seconds a green indicator that
says "Auto" lights up. I could have sworn I used to hear a "click" that
took place when it got to the "auto" stage, which sounded like a solenoid
activating....but I may be mistaken since I actually haven't used the unit
much lately. Could it be a solenoid is shot? If so, how easy would it be
for a novice to replace?

Thanks,

J.

 

[William R. Walsh]

Hi!

That's one of the Technics models that (IIRC) uses a "hybrid" power amplifer
module. Most (if not all) of these modules were made by Sanyo.

(You can find an article about repairing a Telefunken amplifier that uses
these modules here:
http://john.ccac.rwth-aachen.de:8000/misc/rr100rep/. No, it isn't what you
have, but all of these amplifiers are built similarly.)

If you can find the module being sold anywhere and you know how to solder,
you could replace it. There's not much you can do other than that. The
insides of these modules aren't repairable as far as I know.

Be glad the unit didn't damage your speakers when it failed. I've seen a
number of Technics receivers that burned out other internal components or
the speakers that were hooked up to them. Your unit may turn off the speaker
outputs via a relay if failure of the power amplifier module has taken
place.

William

 

[Arfa Daily]

I have a 23-year old (try not to laugh) Technics SA-410 receiver. It
worked fine earlier today, but I went to use it a 2nd time and I'm getting
absolutely no output out of either speakers or headphones. Something
defitely failed within the unit.

It appears to power up. When booting up it has an orange indicator on the
front says "preload" and then after a few seconds a green indicator that
says "Auto" lights up. I could have sworn I used to hear a "click" that
took place when it got to the "auto" stage, which sounded like a solenoid
activating....but I may be mistaken since I actually haven't used the unit
much lately. Could it be a solenoid is shot? If so, how easy would it be
for a novice to replace?

Thanks,

J.

What you used to hear was the speaker protection relay coming in. If it gets
as far as the green light coming on, that basically says that it has
performed its checks, and it thinks that everything is ok. This makes it
unlikely that there has been a failure of the output hybrid or associated
components. It would also make it unlikely that that there is any such
problems as shorted speaker wires or faulty speakers. That doesn't leave
much, other than the relay circuit itself, which in reality means either a
faulty driver transistor or, it being a Technics, bad joints on the relay
coil pins. Another possibility is a problem with the speaker switching from
the headphone socket.

My first moves would be to stick a pair of headphones in the front, and work
the plug in and out a few times to see if that clears the problem. If it
does, squib a little switch cleaner fluid in the socket and repeat. If no
go, take the cover off, and locate the output relay. It will be not far from
the output sockets. It's a small 'box' about 1" x 0.75" x 0.5" and is
usually black, but may be blue. Place a finger on the top and push a
little - down or to the side. If the relay clicks, look underneath for a bad
joint. Beyond this, without faultfinding experience on this sort of kit, I
don't think realistically, you are going to get far without landing the unit
deeper in trouble. FWIW, the problem doesn't *sound* serious on the surface,
based on experience of these things, and it would probably be worth spending
out a little to get a professional opinion if you can't bottom it yourelf.

Arfa