Sony TA-1120 vs 1120A vs 1120F

[sssboa]

Guys, what are those level adjust knobs at the back for tuner and for aux?

BTW
All electrolytic caps replaced now
Around half transistors replaced
Power microswitch and snubber replaced

Amp tested on headphones and seems ok. But headphones only test the preamp really in this model so I am not celebrating yet.
Now I am to set currents and I'm thinking what's about those level adjust at the back.

 

[bberkom]

They are just input level controls that allow you to set the AUX and Tuner input level so that they match each other and whatever other sources you are using, like phono. That way the volume of your sources can be the same across the board at the same main volume control level.

 

[sssboa]

OK, listening to my TA-1120A on speakers now, sipping C**rs Light . Don't see any problems with either. Another success story. Thx averyone for help!

 

[sssboa]

The amp is made for listening loud, this is when solid bass kicks in. Very clear extended middle frequencies, good for vocals and dialogues.
Heats up a bit. Not as much as modern av receivers, but more than my other vintage units.

 

[bberkom]

Mine also runs a little warmer than other similar vintage units I've had, but it never gets too hot to touch or even close to that.

 

[Oldsansui441]

OK, listening to my TA-1120A on speakers now, sipping C**rs Light

Nice work, great to hear it is running nicely.

 

[sssboa]

Mine also runs a little warmer than other similar vintage units I've had, but it never gets too hot to touch or even close to that.

I doesn't run hot any more. Maybe the voltages have dropped, maybe the new caps matured somehow. But it sounds roughly the same. The most heat used to be over the transformer, now it's the coolest place there, with the warmest part on the left side where the biggest cap is. Now the overall heat is on par with my other amps.

The sound is warm, maybe a tad warmer than initially, a lot of low and middle bass, I add some treble to the mix.

 

[sssboa]

I have distortion of sound when using Tape Head source only.
Any reason for this besides dirty selection switch?
I cleaned it BTW, maybe not well enough though.

 

[Oldsansui441]

What source are you using on the tape head input?

 

[sssboa]

What source are you using on the tape head input?

A DAC like with other inputs, I have a few DACs I use. I switched to to Tuner input and it's ok. Is there any separate circuit for processing signal from Tape Head? I use Tape (not Tape Head), Aux and Tuner inputs, these work ok. I haven't tested Phonos yet.

Also I just realized that I didn't press the diode boards on the other side of main amps against the metal plate for cooling or temperature measuring, whatever it's for. Must disassemble it again.

 

[Oldsansui441]

The tape head input will distort with a line level input. It is designed to be used with a tape player with very low output, similar level to a turntable output level but with a different eq curve.

 

[RobinTW]

Hi,
I’m liking the discussion on the transistors and the rebuild, as I’ll eventually dig into my 1120F, although I can’t locate a schematic yet.
View attachment 1377834

Any luck on finding 1120F's schematic?
How do you adjust the DC-offset?

thanks

 

[bberkom]

At least on the TA-1120A, there is no DC offset adjustment. It's a cap-coupled design anyways. There is an idle bias adjustment and a voltage centering adjustment on each channel's driver board on the TA-1120A. To set bias, you measure voltage across an emitter resistor like you do in a lot of amps. To center the rail voltage, I measure at each of the main filter caps and set each to half of the total PS voltage. You can use a scope to do this as well, but setting each to half of the total works just as well.

 

[sssboa]

At least on the TA-1120A, there is no DC offset adjustment. It's a cap-coupled design anyways. There is an idle bias adjustment and a voltage centering adjustment on each channel's driver board on the TA-1120A. To set bias, you measure voltage across an emitter resistor like you do in a lot of amps. To center the rail voltage, I measure at each of the main filter caps and set each to half of the total PS voltage. You can use a scope to do this as well, but setting each to half of the total works just as well.

I am not sure the F version is cap-coupled, it's from 1973 or so, also quick look at caps and it has 2 big filter caps and next to it 2 small but of different size. It could be more comparable to Sony TA-1130 than TA-1120(A). Research needed.
Below Sony TA-1120F

 

[sssboa]

Yeah, below picture of TA-1130

 

[bberkom]

I am not sure the F version is cap-coupled, it's from 1973 or so, also quick look at caps and it has 2 big filter caps and next to it 2 small but of different size. It could be more comparable to Sony TA-1130 than TA-1120(A). Research needed.
Below Sony TA-1120F

View attachment 1419780

Yep, very different from the A version. Probably a very different procedure.

 

[RobinTW]

Yeah, below picture of TA-1130

View attachment 1419789

Is it possible they share the same power amp design?

 

[sssboa]

Is it possible they share the same power amp design?

It is possible but how can we know if we don't have schematics for F version.
I would download service manual for TA-1130 and see if I can somehow apply it to TA-1120F. I know Sony were juggling those modules in that era, different models share amp/preamps.

 

[sssboa]

From select45rpm.com

Sony TA-1120F amplifier ↑
Interesting. The third version of the 1965 TA-1120, the second was the 1967 TA-1120A & this 1971 TA-1120F is a strange mix of the TA-1120A preamp & the Semi Complimentary TA-1130 amp that came later in 1971. Absolutely no circuits or service manuals findable for free or to buy even for the TA-1120F which is a pity though it'll likely be a mix of the two with minor changes. The preamp has big green coupling capacitors not the kooky big red ones though the Tone stage still has some. The front still has L+R Microphone as the 1120A has on the back, no Tape Head, 'F' stuck on letter on the fascia & still the smooth control knobs. The rear has the 1120A type speaker connectors but the TA-1130 type heatsink & 2 main capacitors for ± voltage. Apparently sold from 1971 to 1976 if clearly few made it to Europe, one on ebay is in the USA. Seems strange to make a third version then quickly issue the TA-1130 with FETs in the preamp, what the 'F' stands for here looking at the boards will be different to the limited spec of the TA-1130. Appears the 1120F is on a lot of websites only in Japan, maybe it was only for the Japanese market & sold well there, but other markets got the 1130 & 1140.

 

[RobinTW]

From select45rpm.com

Sony TA-1120F amplifier ↑
Interesting. The third version of the 1965 TA-1120, the second was the 1967 TA-1120A & this 1971 TA-1120F is a strange mix of the TA-1120A preamp & the Semi Complimentary TA-1130 amp that came later in 1971.

Good to know. Many Thanks. I am still waiting for my newly purchased 1120F to come home.