Sony TA1130 low volume?

[novicerepairer]

Hi, I wonder if anyone can help . I have just bought from eBay, a Sony Ta1130
On testing all seems good apart from the volume control needs to be between 10-11 o’clock on tape, or tuner to get a reasonable volume. On most of the other amps I have ( less powered) I would obtain the same at 9 o’clock. Could it be just the trait of the volume control, or something more sinister? The sound quality seems ok , just was expecting more punch? Thanks in advance.

[Ted Kendall]

If that's the only issue, there's nothing wrong. It's usual to have the volume control in the middle third of its travel at normal listening levels, and this is unrelated to the available power.

[novicerepairer]

Originally Posted by Ted Kendall

If that's the only issue, there's nothing wrong. It's usual to have the volume control in the middle third of its travel at normal listening levels, and this is unrelated to the available power.

Thanks so much for getting back so quickly and putting my mind at rest. I was not sure if it was the result of a need of a re cap, or the output transistors on the way out.

[Ted Kendall]

Neither of the causes you mention would affect volume only in both channels at once - distortion or absence of signal would be a more likely sign. In any case, wholesale re-capping of decent domestic kit is seldom necessary, however popular it may be in some quarters. Aside from the fact that Japanese capacitors from as far back as the 1970s have, in general, lasted very well, it is all too easy to put one in the wrong way round and cause an obscure fault. As things stand, if it ain't broke, enjoy it!

[novicerepairer]

Thanks so much Ted. It is in Superb cosmetic condition. I have just got caught up in the look how loud my amp is! And it’s only on No 2!
It has been so reassuring to hear your comments and look forward to just enjoying it now. Thanks again for taking the time to educate and put my mind at rest. Regards, Colin.

[Mooly]

An older amp like this has (by modern standards) a high input sensitivity meaning that full output is achieved with relatively low levels of signal.

The specs mention 130 millivolts into 100k which is bang on the money for something of this age. Now the problem with this is that when such equipment is used with modern source equipment like a CD player then the amp should be really loud for very little rotation of the volume control. A typical CD player puts out around 2 volts rms at full output by way of comparison.

Thoughts... and first thing to say is don't fret over this. Its a nice amp and good cosmetic condition is everything imo.

1/ We don't know what your source is in terms of signal level. If it is similarly old components of this era then I would say its normal. To make any judgement we need to know what you applying to the inputs in terms of level.

2/ If you are using modern source components (like a CD player) then could the amp have been modified by a previous owner such as by fitting attenuators somewhere.

3/ It is easy to check it meets its specification but you would need some means of accurately measuring signal voltages applied to the input and the levels appearing at the speaker output. You would also need a pure test tone of around 400 to 1 kHz which is easy to generate and store as an MP3 file to play on something suitable.

The test can be done at low levels with a bit of calculation... and you don't even need speakers connected. A typical DVM may lack resolution to measure small AC voltages however and a scope is really the best tool for the job here.

And if it hasn't been altered in some way then I would very much doubt there is a problem. Transistors have no impact on gain of the complete circuit, capacitors would probably show other symptoms such as tonal imbalance rather than level issues, and they would almost certainly differ between channels.

[novicerepairer]

Thanks Mooly, for your detailed reply.
Too technical for me I’m afraid. I have the day to myself tomorrow though, so I am going to give it a good clean and have a quick look under the bonnet.
I will probably give the control a quick clean/lube while I am in there.
The tuner I used was a 1979 Pioneer tx9800 on a fixed output and some mission 771’s.
I was just surprised to have to have it approaching half volume before getting some decent loudness. And I have a ta1150 already, that is 15 watts per channel less and I don’t use above 1/4 volume, but as the other kind man informed me , apparently this doesn’t really mean anything. Thanks so much for spending the time to reply in such detail. I agree, having it looking as new is the most important part. If it becomes a concern, I will have someone give it a check over. I was just worried the Fet transistors were on the way out, as I have heard they are quite hard to find for replacing. The main thing that you and the other kind person that replied is it has reassure my purchase as a good one. Thanks again, Colin.

[Mooly]

Don't worry over transistors, the high power output stage on the TA1130 uses conventional bjt transistors. You are maybe thinking of the special VFET power transistors used in a handful of designs.

The only FET's in this amp are in the preamp section and these are just small signal types. The gain of all the circuits is set by the circuit design (the feedback factors and ratios) and these are determined purely by the value of the passive parts (resistors).

The actual transistor characteristics for gain and so on have no impact on the gain of the finished amplifier as far as the user is concerned i.e if you made the amplifier with transistors of gain =40 and another with transistors of gain =200 then the gain of the overall amplifier would still be the same.

The Pioneer tuner will almost certainly have a low (by todays standards) output level and so if that is the only source you have tried then I would say what you experience is probably more in the realm of normal than not.

A good visual inspection is worthwhile. Check for signs of any previous work, make sure the volume control and balance control look original.

[novicerepairer]

Thanks again for your reply and giving me the info on the availability of the transistors. That’s another worry out the way! I initially contacted the seller and stated my concerns. I will now go back and let him know, I think it’s working to spec and put this to bed and start enjoying the sounds of the seventies. It’s a great help having these forums and the kind people like yourselves that share their knowledge. Cheers, Colin.

[Mooly]

That's it it really is one to enjoy.

There is a full service manual available on HiFi Engine if you want to look the design over. Its free but you have to register first.

[novicerepairer]

Thanks, I have done that. Just need a few years to try and learn what it all means! I’ll keep trying though. Thanks for letting me know. Colin.

[Mooly]

Well if you are not sure on anything or just want to know how something on it works then just ask.

----------------------------------------------------

The manual does actually give a nice representation of the gain from input to output. For example the top right shows 19.5v, lets call it 20v. 20v (rms) into 8 ohm is 50 watts. Moving to the left we come down to the next figure, 1 volt. This is the input to the power amp section. So that stage has a numerical gain of 20 meaning 1 volt in gives 20 volts out and so on.

And so it goes on as we work back toward the input sockets. All those levels or ratios can be measured and confirmed as correct by simple voltage tests of signal levels at the key points.

An oscilloscope is really needed for such work although a DVM with good resolution of AC voltages could also be used.

I shall leave it at that... enjoy.

[novicerepairer]

Wow! It’s nice to know there is people like you out there. If I get stuck. Everything inside looked like new, just gave it a few puffs of air and did the easily accessible pots and switches with cleaner/lube. I then put it in a different room with different speakers and although still needed plenty of knob turning (I don’t think that’s the right terminology!) it sounded superb. Definitely happy with the purchase.

[Mooly]

Thanks for the kind words... all I can say is enjoy

Most of the old Sony equipment was superbly built and I still have a Sony TCK5 cassette deck and ST515 tuner in original electrical condition although I think yours predates those a little.

[Radio Wrangler]

Early on in the thread, you used the word 'recap'

This is a warning sign. It is mostly used by people who can't do fault-finding. "There's a bad part in that set, and I can't find out which it is, so I'll change them ALL". Sometimes it's "I don't like how that thing sounds, there might be a bad part in it, so I'll change EVERYTHING and see if that fixes it"

It is a valid method of repairing something, but it is very invasive and the large amount of work has a high risk of introducing an added mistake. It also disturbs everything and may remove the evidence pointing to what the real fault was.

In other words, it is a process which should be nearer the last resort, not the first.

There are exceptions, of course. Some parts are known to be far past their reliable life, and an experienced repairer will replace them on sight... waxed-paper capacitors absorb water and go leaky. Some makes of electrolytic capacitors are known trouble (Plessey, Callins, etc) some paper capacitors in resin cases and even in metal tubes sealed with little rubber bungs are known trouble makers. You'll find that most people on the forum swap these things on sight.

You are very unlikely find any of these things in transistorised gear from Sony.

The Japanese equipment and component manufacturers put in place some continuous quality improvement processes a long time ago. It was an intentional plan. Japan once had a reputation for making cheap junk, and their ministry of trade wanted to escape this reputation and move the whole country into higher quality (and more profitable!) products.

They succeeded. As a result, Japanese capacitors from the seventies onwards have been the standards against which all others are judged in terms of reliability and life expectancy. So much so that for several years now there has been a flow of cheap and nasty electrolytic capacitors out of China which have been marked to fake respected Japanese makes.

So the minefield is that if you take out all the capacitors and replace them with new ones, there is a high risk that you may be fitting fraudulently faked rubbish in their place. Designers of equipment which has to be reliable (I used to design things which linked aircraft into anti-collision systems and air traffic control) have to be VERY careful about where they buy components, especially electrolytic capacitors, from. It's a case of buying from major distributors like RS, Mouser or Farnell - firms which very carefully manage their stock and manage supply lines to ensure the parts they sell are not fakes. The highest risk is if you just hit the internet and buy the lowest price.

In modern equipment, the problem capacitors are the electrolytic ones.

The vast majority of these use an electrically conductive liquid as one of their electrodes. The liquid is water based, and the water can evaporate, faster the hotter they are. These capacitors rely on seals to keep the water vapour in, and the life expectancy of the capacitors depends on the quality of the seals, the temperature they run at, and how much water they started out with.

These parts have safety valves, designed to release pressure if they get too hot - like tiny boilers! In some cases these are weakened paterns pressed into the tops of their aluminium cans, or blow-out plugs.

A visual inspection can find electrolytic capacitors which are bulging, on the point of bursting, or others which have leaked out their fluid (electrically conductive and corrosive - not good news to see on a printed circuit board, it will have shorted things and likely done further damage)

The invisible failed or failing electrolytics exhibit increasing ESR (equivalent series resistance) as their electrolyte dries out through loss of water vapour. You can get little ESR meters to check these in circuit. From seeing the measured ESR and comparing to what a new part should show, you can dip the tank and see how much life is left.

'Recapping' has become a cult thing, starting from America. But it's a very blunt tool and has a number of disadvantages and risks. Sometimes it is the right thing to do, but you should never go into it blind.

So beware of anyone using that word as if it was a straight-forward process. Definitely beware of anyone touting it as a miracle cure. These are valuable clues that someone hasn't got a scoobie about what they're saying.

Yes, I have recapped one piece of equipment. It was a very classy Revox FM tuner which had spent about 20 years running continuously in a rack of equipment at the BBC. It had run hot and continuously. There was some hum on the audio output. Inside, one main reservoir capacitor had been replaced (by an unrecognised brand) it was OK, but not ideal in a piece of very high quality gear. In went something trustworthy. The hum wasn't fixed, of course. That was traced to a small, low value electrolytic in a power supply regulator. There were many dozens of the same part sprinkled throughout the tuner. A check round them showed that about 50% of them were showing increased ESR. I measured a lot of other value small electrolytics and found the same thing. So I set out and replaced all the electrolytics in the box. But remember that this equipment had started out with good quality parts, but had run 24/7 for 20 years in an oven! Notice also that I'd traced the original fault and fixed it first, so I understood what had been wrong and therefore why my fix was a good one. The recapping bit was a pre-emptive strike on some components measurably approaching the end of their lives. Some of them had gone low in capacitance as well, and after their replacement, yes it did sound better. There was an improvement in its bass.

Hope this helps a bit.

David

[novicerepairer]

Thanks for your advise too. I have a bit of dilemma with a Trio KA3500 I own . It has a couple of smallish leaking caps that have leaked on to a resistor as well, but it plays and sounds fine. Because I have never replaced a capacitor, I wonder if to give it a go or just enjoy until something more sinister happens. I am worried if I try replacing, if there will be damage made to the board. Thanks, Colin.

[Mooly]

Firstly are you sure it is leakage? Some caps can be mechanically secured to the PCB with a glue.

A good picture might help us if you are still unsure.

[Radio Wrangler]

Other colours of adhesive are used. some is rubbery, some goes quite hard. Some looks like silicone bathroom sealant piped in by a mini mastic gun... A special grade of silicone that doesn't give off acetic acid as it sets.

Leaked electrolyte is wet when fresh, but dries to leave a deposit which may look somewhat crystalline.

It's easier to say which it is from a photo than it is to describe!

David

[novicerepairer]

Thanks for your replies, I have a busy weekend unfortunately, but will try and get a picture for you, as soon as I can. Thanks both of you for getting back to me. Colin.

[novicerepairer]

Hi, I have just managed to take a couple of Pics while the other half and kids are out!