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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 16th Sep 2019, 12:52 pm   #21
barrywebb
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Default Re: Technics SA-303L amp

Hi i have managed to up load some pictures for you all.
Barry.
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Old 17th Sep 2019, 6:27 am   #22
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Default Re: Technics SA-303L amp

Right, so it's an old tuner/amp, hopefully the same as the bog standard 303 without LW, the amp section that is. If you flip it over does it have a panel that comes off the bottom to get access to the bottom of the PCB?

Andy.
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Old 17th Sep 2019, 8:53 am   #23
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Default Re: Technics SA-303L amp

Awkward question time....

Does this amplifier have any special significance for you? Because it's a bit of an economy model and if it has those STK modules in it as the power amplifiers, they aren't easy to find, nor are they cheap. There are plenty of other amplifiers floating around for not much money (sometimes free) and you can find better ones, higher quality, more power etc all at rock bottom prices if you look around and know what to look for.

You might want to repair it because of a family connection or something like that, or just for the challenge and learning exercise. Mind you, you'd learn more from one using discrete transistors than power modules.

Sorry for being a party pooper

David
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Old 17th Sep 2019, 12:27 pm   #24
barrywebb
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Default Re: Technics SA-303L amp

Quote:
Originally Posted by Diabolical Artificer View Post
Right, so it's an old tuner/amp, hopefully the same as the bog standard 303 without LW, the amp section that is. If you flip it over does it have a panel that comes off the bottom to get access to the bottom of the PCB?

Andy.
Hi yes it does have a panel i have taken if off and here is a photo of it if you can help in anyway.
Barry
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Old 17th Sep 2019, 12:59 pm   #25
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Default Re: Technics SA-303L amp

If you can't see anything obvious and the switches are working ok and you have the service manual all the relevant voltages on the IC's, transistors etc are given both in the schematic and in the layout, you can check them from the side of the panel as shown in your last photo, all measured with respect to ground/chassis (0v)

If you don't have the manual you can down load one from elektrotanya without having to register.

The voltages in the schematic for the output stages are shown for the right hand channel, the voltages for the left hand channel should be the same.

When doing voltage checks on solid state equipment be careful not to short anything out when probing around....IC's. transistors etc don't like shocks and more often than not they won't recover if they get one.

Lawrence.
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Old 18th Sep 2019, 6:36 am   #26
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Default Re: Technics SA-303L amp

As David says worth having a think before diving in, still, there's different ways of tackling this, 1) Thoult shall measure voltages" as Lawrence says and 2) bung a signal in one end, see where it stops. Whichever, having easy access makes your life lots easier.

It's tricky for us to advise, more than we have done so far, check the voltages round the STK module first, as Lawrence says. I might have a spare if not these haven't been made for years and are getting hard to find.

Andy.
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Old 18th Sep 2019, 7:50 pm   #27
barrywebb
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Default Re: Technics SA-303L amp

Hi and thanks again for all your help i have a Friend that has had a look at the pictures and hes pretty sure that its the STK 1039 Power amp chip that gone i have ordered a clone one from Germany once fitted i will report back.
Barry.
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