Technics SA-500

[ZigDaPig]

Just bought a Technics SA-500 receiver on Ebay. It was supposed to be 100% OK, but (what's new) it's not... :-(
I even paid (shipping included) 115 Euro...
I know, that's a lot, but I really think it's a beautiful piece of equipment...

First of all, most switches and pots seem very dirty and can cause very instable sound (sound dropping away or very distorted when wiggling the switches...)
This I can probably fix -> if you have any tips on how to clean them, they're also welcome.

However, the right channel is ALWAYS weaker than the left channel, independent of the source.
If I turn the balance 2/5 to the right, the sound is balanced.
Can someone help me find out how to fix this ?

Second (and less important), the fm tuning meter doesn't seem to work correctly:
When the FM tuner is not active, it is hanging nicely in the middle.
When the FM tuner is on and NOT tuned, the needle is about halfway to the left.
When the FM tuner is tuned to a station, the needle is a quarter to the left...
The meter NEVER goes to the right.
Is this normal ? (I've never had a tuning indicator like this, so I'm not sure on what would be normal behaviour...)


Z.

 

[Netlist]

I think the receiver needs a good cleanup.
Look for replaced components, bad solderings, the tape/source switch in those amps are often bad.
Re. Tuner, from this picture.
The left meter should be as far to the right as possible, indicating a good reception/strong station.
The right meter should be in the middle when perfectly tuned into the desired station. Of course you need a decent antenna.
If not, the tuner is out of spec.

/Hugo

 

[anatech]

Hi ZigDaPig,
Don't do anything until the switches and controls are cleaned. Use a proper contact cleaner (as little as possible), not tuner cleaner (different stuff).

Your tuner is out of alignment. Even with a weak signal the centre tune meter should be centered. Do not touch it yourself ! This is a job that requires test equipment and knowledge. You can only make things worse. Once the rest is working well, take it to a technician that really knows what they are doing. Not a friend unless they actually do this for a living!!!!!!! and !!!!!!!!. Once set up the tuner will sound great.

I've had to fix several "twiddled" sets over the years. Some from well known shops. Those sets can take hours to fix. Read $$$ -So don't "twiddle" the controls.

-Chris

 

[ZigDaPig]

Thanks already guys !
I'm already taking it apart carefully to clean it...

Could you give me a few clarifications on the next things too ?

- Hugo, when you say the left meter should be to the right on
good reception, does that also count for FM reception ?
Now it is only working on AM reception.

- Chris, I won't touch the tuner (wouldn't know how to fix this anyway), but what do you mean by "twiddling" the controls ?

- The tape/source switch (as well as the others) are encapsulated in a metal housing. Should I just use a little contact spray from outside to inside or should I try taking the switch apart ?

Thanks,

Z.

 

[Netlist]

I "think" the left meter is signal strength for FM.
You should have two antenna inputs on the back. One AM, one FM. Both need a separate antenna in order to have good reception. These old receivers tend to have a good sensitivity, a little wire will do just to test and receive the strongest channels.

Don't take the switches apart. It's not or almost not possible anymore to reassemble them and finding new ones is probably out of the question. Just try cleaning them as Chris suggested, a little bit of spray from outside to inside trough the small holes in the metal housing. Then toggling the switches should give result if that's the cause of the problem.

/Hugo

 

[anatech]

Hi ZigDaPig,
"Twiddling" is the act of adjusting a control to see if it makes things better. Sounds like fiddling and that's what it is. There are sometimes ferrite slugs. If one is broken, you are in trouble. With the wrong tool it is easy to break them. I am talking about trimmer pots, capacitors and tuning slugs in the small transformers.
As Netlist suggested, you can get the fluid in the control from the top through the circular holes. There is almost always some type of opening. Check the rear where the metal is bent over the back if there are no holes.

-Chris

 

[ZigDaPig]

Too bad I live in Belgium

Hi guys,

Thanks for the advice,
it already sounds a lot better now.
But still no balanced channels though, and as for the
FM tuner I'm also having bad luck...
I can't find anyone here in Belgium who repairs
and / or aligns vintage tuners...
Too bad, but I still hope to find a perfect SA-700
one day...

Regards,

Z.