Sony TA-1010 noisy phono circuit - UK Vintage Radio Repair and Restoration Discussion Forum

Nickaliath · 4th Dec 2022, 9:26 pm

Hello All,

I've started to have a look at my Sony TA-1010 amplifier, to see if I can sort out the noisy phono circuit.

Playing through all of the other inputs, it is absolutely fine. But when I select phono 1 or 2, the music comes out crackly / distorted.

I've done a quick visual check of the capacitors on the pre-amp and power amp board. None are throwing up any issues that I can tell.

Also I have tried to find information around various sites and some point toward faulty transistors. Apparently the type of transistor on the pre-amp are prone to failure. I happened to have some new equivalent spares lying around, so fitted those 4. However, it didnt make any difference.

So instead of chucking more parts at it, i wondered if anyone would have any ideas of where to go next?

manual is linked at https://audio-circuit.dk/downloads/s...010-int-sm.pdf

DMcMahon · 4th Dec 2022, 10:36 pm

What turntable/record deck cartridge are you using for the phono inputs ?

This amplifier is intended to be used with Moving Magnet (MM) cartridges.

If you are using an old fashioned Ceramic or Crystal cartridge, then it almost certainly would overload the phono inputs and cause distorted signal.

If you are using a modern Moving Coil (MC) cartridge, then it would not give good results into a MM phono input.

David

Silicon · 4th Dec 2022, 11:18 pm

C101 and C106 in the phono equalizer stage are 1uF electrolytic capacitors.

Small electrolytic capacitors have a tendency to dry out.
They are not the easiest components to verify as working OK.

If there was room on the circuit board I would try to replace them with film type capacitors.

The signal from a moving magnet cartridge might be in the region of 5mV.

Nickaliath · 5th Dec 2022, 9:22 am

Ah, ok. Maybe that explains it then.
I initially plugged in a random 90's sony turntable, Which ive now sold.
I then plugged in an RCA to 3.5mm jack into a digital walkman

. Just as a test.

I never realised this would do this and it was only compatible with a certain input type.

Glad I put the message on here now and did think it was weird the other inputs are perfect.

Quote:

Originally Posted by DMcMahon

What turntable/record deck cartridge are you using for the phono inputs ?

This amplifier is intended to be used with Moving Magnet (MM) cartridges.

If you are using an old fashioned Ceramic or Crystal cartridge, then it almost certainly would overload the phono inputs and cause distorted signal.

If you are using a modern Moving Coil (MC) cartridge, then it would not give good results into a MM phono input.

David

Nickaliath · 5th Dec 2022, 9:23 am

Thanks for the quick replies, its appreciated.

DMcMahon · 5th Dec 2022, 9:40 am

The input sensitivity of these Phono inputs is 1.2mV at 47kOhms so a very sensitive input, the TA-1010 specification states that 30mV is the maximum input capability.

If the Walkman signal was anywhere near line level, then it would easily overload a phono input.

David

Nickaliath · 5th Dec 2022, 10:07 am

Sounds like it's definitely the issue. I will try a different turntable when I have one available.

Thanks for the rapid responses, it saves a lot of time.

Thanks

TIMTAPE · 5th Dec 2022, 11:54 am

It's not just a case of overload distortion: you may have been lucky not to have nuked the phono amp transistors.

Nickaliath · 5th Dec 2022, 1:55 pm

Yeah, I've definitely learned something with these replies.
Hopefully they will be ok, as I kept the volume low (if that means anything).

Will soon find out when i get the chance to check on a suitable turntable.

Quote:

Originally Posted by TIMTAPE

It's not just a case of overload distortion: you may have been lucky not to have nuked the phono amp transistors.

DMcMahon · 5th Dec 2022, 3:24 pm

The bottom line is that phono inputs on an amplifier should only be used for turntable/record deck signals, in this case with a moving magnet cartridge.

Another device with low (< 30mV) signal output + matching impedance maybe could be used, but due the phono pre-amplifier applying RIAA equalisation may not sound quite right.

David

dave cox · 5th Dec 2022, 4:38 pm

Although ...
This does use use transistors KNOWN to sometimes go noisy / bad in the RIAA Eq stage. No problem if this is the case, it can be fixed for a few pennies

I would think the 'phones output', with the volume turned down as low as it will go (on the walkman), should not overload the input. As already mentioned, the RIAA Eq will make it sound rather unusual, like you turned the treble to maximum and the bass to minimum. Having said that, some digital amplifiers (in the walkman) don't play nice if they don't have a low enough load impedance but the better brands work just fine ...

dc

Nickaliath · 5th Dec 2022, 6:23 pm

Yeah, I read that these transistors have known issues. This is why i initially thought it may have been this, so changed all of them on the pre-amp. Which diagrams show are connected to phono (if im correct).

The left channel does have some random crackling at times, But the right is fine. As it happens I do have quite a few compatible transistors, from a previous repair.

Quote:

Originally Posted by dave cox

Although ...
This does use use transistors KNOWN to sometimes go noisy / bad in the RIAA Eq stage. No problem if this is the case, it can be fixed for a few pennies

I would think the 'phones output', with the volume turned down as low as it will go (on the walkman), should not overload the input. As already mentioned, the RIAA Eq will make it sound rather unusual, like you turned the treble to maximum and the bass to minimum. Having said that, some digital amplifiers (in the walkman) don't play nice if they don't have a low enough load impedance but the better brands work just fine ...

dc

Herald1360 · 5th Dec 2022, 9:54 pm

Quote:

Originally Posted by dave cox

Although ...
This does use use transistors KNOWN to sometimes go noisy / bad in the RIAA Eq stage. No problem if this is the case, it can be fixed for a few pennies

I would think the 'phones output', with the volume turned down as low as it will go (on the walkman), should not overload the input. As already mentioned, the RIAA Eq will make it sound rather unusual, like you turned the treble to maximum and the bass to minimum. Having said that, some digital amplifiers (in the walkman) don't play nice if they don't have a low enough load impedance but the better brands work just fine ...

dc

Surely the RIAA compensation would boost the bass and attenuate the treble ie bass to maximum and treble to minimum?

Chris55000 · 6th Dec 2022, 1:47 am

Just as an aside, you can get a nice colour scan of the original Sony TA–1010 book with nice turquoise PCB track layout Diagrams in it from here, free of charge :–

https://freeservicemanuals.info/en/s...al/Sony/TA1010

Chris Williams

Radio Wrangler · 6th Dec 2022, 4:47 am

Quote:

Originally Posted by Herald1360

Surely the RIAA compensation would boost the bass and attenuate the treble ie bass to maximum and treble to minimum?

That's the response to noise coming into the stage.

For noise created within the stage, the result isn't necessarily the same.

David

Nickaliath · 6th Dec 2022, 9:50 am

Thanks very much for that.
The manual i was using, was awful. I couldn't find another, so this is perfect.

Quote:

Originally Posted by Chris55000

Just as an aside, you can get a nice colour scan of the original Sony TA–1010 book with nice turquoise PCB track layout Diagrams in it from here, free of charge :–

https://freeservicemanuals.info/en/s...al/Sony/TA1010

Chris Williams

Nickaliath · 6th Dec 2022, 4:22 pm

I decided to replace all the transistors on the power amp board, as these are known noisy transistors.

I had a load of spares anyway, so whilst it was open i thought i might as well.

Luckily the noise on the left channel has now gone, So these must have been the culprit.

4th Dec 2022, 9:26 pm	#1
Nickaliath Triode Join Date: Aug 2022 Location: Somerset, UK. Posts: 49	Sony TA-1010 noisy phono circuit Hello All, I've started to have a look at my Sony TA-1010 amplifier, to see if I can sort out the noisy phono circuit. Playing through all of the other inputs, it is absolutely fine. But when I select phono 1 or 2, the music comes out crackly / distorted. I've done a quick visual check of the capacitors on the pre-amp and power amp board. None are throwing up any issues that I can tell. Also I have tried to find information around various sites and some point toward faulty transistors. Apparently the type of transistor on the pre-amp are prone to failure. I happened to have some new equivalent spares lying around, so fitted those 4. However, it didnt make any difference. So instead of chucking more parts at it, i wondered if anyone would have any ideas of where to go next? manual is linked at https://audio-circuit.dk/downloads/s...010-int-sm.pdf

4th Dec 2022, 10:36 pm	#2
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 5,737	Re: Sony TA-1010 noisy phono circuit What turntable/record deck cartridge are you using for the phono inputs ? This amplifier is intended to be used with Moving Magnet (MM) cartridges. If you are using an old fashioned Ceramic or Crystal cartridge, then it almost certainly would overload the phono inputs and cause distorted signal. If you are using a modern Moving Coil (MC) cartridge, then it would not give good results into a MM phono input. David

4th Dec 2022, 11:18 pm	#3
Silicon Octode Join Date: Jun 2007 Location: Coulsdon, London, UK. Posts: 1,758	Re: Sony TA-1010 noisy phono circuit C101 and C106 in the phono equalizer stage are 1uF electrolytic capacitors. Small electrolytic capacitors have a tendency to dry out. They are not the easiest components to verify as working OK. If there was room on the circuit board I would try to replace them with film type capacitors. The signal from a moving magnet cartridge might be in the region of 5mV.

5th Dec 2022, 9:23 am	#5
Nickaliath Triode Join Date: Aug 2022 Location: Somerset, UK. Posts: 49	Re: Sony TA-1010 noisy phono circuit Thanks for the quick replies, its appreciated.

5th Dec 2022, 9:40 am	#6
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 5,737	Re: Sony TA-1010 noisy phono circuit The input sensitivity of these Phono inputs is 1.2mV at 47kOhms so a very sensitive input, the TA-1010 specification states that 30mV is the maximum input capability. If the Walkman signal was anywhere near line level, then it would easily overload a phono input. David

5th Dec 2022, 10:07 am	#7
Nickaliath Triode Join Date: Aug 2022 Location: Somerset, UK. Posts: 49	Re: Sony TA-1010 noisy phono circuit Sounds like it's definitely the issue. I will try a different turntable when I have one available. Thanks for the rapid responses, it saves a lot of time. Thanks

5th Dec 2022, 11:54 am	#8
TIMTAPE Octode Join Date: Jul 2006 Location: Perth, Western Australia Posts: 1,822	Re: Sony TA-1010 noisy phono circuit It's not just a case of overload distortion: you may have been lucky not to have nuked the phono amp transistors.

5th Dec 2022, 3:24 pm	#10
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 5,737	Re: Sony TA-1010 noisy phono circuit The bottom line is that phono inputs on an amplifier should only be used for turntable/record deck signals, in this case with a moving magnet cartridge. Another device with low (< 30mV) signal output + matching impedance maybe could be used, but due the phono pre-amplifier applying RIAA equalisation may not sound quite right. David

5th Dec 2022, 4:38 pm	#11
dave cox Octode Join Date: Jan 2009 Location: Bristol, UK. Posts: 1,955	Re: Sony TA-1010 noisy phono circuit Although ... This does use use transistors KNOWN to sometimes go noisy / bad in the RIAA Eq stage. No problem if this is the case, it can be fixed for a few pennies I would think the 'phones output', with the volume turned down as low as it will go (on the walkman), should not overload the input. As already mentioned, the RIAA Eq will make it sound rather unusual, like you turned the treble to maximum and the bass to minimum. Having said that, some digital amplifiers (in the walkman) don't play nice if they don't have a low enough load impedance but the better brands work just fine ... dc

6th Dec 2022, 1:47 am	#14
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,408	Re: Sony TA-1010 noisy phono circuit Just as an aside, you can get a nice colour scan of the original Sony TA–1010 book with nice turquoise PCB track layout Diagrams in it from here, free of charge :– https://freeservicemanuals.info/en/s...al/Sony/TA1010 Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

6th Dec 2022, 4:22 pm	#17
Nickaliath Triode Join Date: Aug 2022 Location: Somerset, UK. Posts: 49	Re: Sony TA-1010 noisy phono circuit I decided to replace all the transistors on the power amp board, as these are known noisy transistors. I had a load of spares anyway, so whilst it was open i thought i might as well. Luckily the noise on the left channel has now gone, So these must have been the culprit.