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John Horner John Horner is offline
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Default Fixed Sony TA-F555ES Integrated Amplifier Today

I suspect that this is a common failure, so I am putting my fix out
there in the wild should anyone else want to use what I learned.

I purchased this amp in the early 1980s and have always liked it. It
was from Sony's high end specialty line at the time.

The problem was that the speaker protection circuit first started taking
a long time to kick in after power on and then eventually wouldn't kick
in at all. You can tell this by the fact that the LED in the volume
knob would stay red instead of turning green and the tell tale sound of
the speaker relays kicking in never happened.

I bought a scan of the schematics off the net. A bit of a rip off, but
I couldn't find free ones.

From the way the problem developed I figured that it was probably a
capacitor which had gotten old. Oddly enough, the circuit is split with
some components on the main board and some on the power supply board.

So, I replaced capacitors C404 (10 uF,16V), C405 (100 uF, 25V), C406 &
C421 (both 10 uf, 50 V NON-POLARIZED). Based on the circuit diagram I
suspect that C405 was the main trouble maker. It looks to me like R406
and C405 create the RC time delay which is an input trigger to the
HA12002 control IC. All of the caps I changed out are on the power
supply board. Be very carefull, those traces lift from the board very
easily. Even with care I buggered two of them up and had to do a bit of
add on wiring to make things right. For everything except the
non-polarized caps I was able to purchase replacement units with higher
voltage ratings. Maybe these will last 40 years .

Finally, I also switched the rear panel speaker impedance selector to
the 4-8 ohm setting. I found out that all this does is to lower the
voltage rails to the output stages and thus limit the peak current
availability. I never push this amp hard, and given it's age I feel
that pulling back on the output drive voltage a little might buy me some
extra lifetime.

Happy Listening!

John
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James Lehman James Lehman is offline
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Default Fixed Sony TA-F555ES Integrated Amplifier Today

It's nice to win one every once and a while. Congratulations!

James. )



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John Horner John Horner is offline
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Default Fixed Sony TA-F555ES Integrated Amplifier Today

James Lehman wrote:
It's nice to win one every once and a while. Congratulations!

James. )




Thanks. I wonder how many other bad or marginal electrolytics there are
in there. The circuits are chock full of the little animals and this is
a very hot running amplified. Even under no load it gets quite warm.
Perhaps some of the stages are biased more in a Class-A style as opposed
to Class B or AB.

John

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James Lehman James Lehman is offline
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Default Fixed Sony TA-F555ES Integrated Amplifier Today

Do you think that the electrolytic juice got cooked out?

I wonder what steps , if any have been taken to prolong the life of a
capacitor in the last 25 years.

I have several amps from the late 70's, early 80's.

I'd like to think that when you get something like that, it should last
forever.

I know one thing... I never buy speakers with foam surrounds any more. I
don't even look at them. I go straight for the butyl rubber or treated cloth
or whatever.

James. )


"John Horner" wrote in message
news:4YSEg.12884$Z1.10502@trnddc03...
James Lehman wrote:
It's nice to win one every once and a while. Congratulations!

James. )




Thanks. I wonder how many other bad or marginal electrolytics there are
in there. The circuits are chock full of the little animals and this is
a very hot running amplified. Even under no load it gets quite warm.
Perhaps some of the stages are biased more in a Class-A style as opposed
to Class B or AB.

John



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John Horner John Horner is offline
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Posts: 5
Default Fixed Sony TA-F555ES Integrated Amplifier Today

James Lehman wrote:
Do you think that the electrolytic juice got cooked out?

I wonder what steps , if any have been taken to prolong the life of a
capacitor in the last 25 years.

I have several amps from the late 70's, early 80's.

I'd like to think that when you get something like that, it should last
forever.

I know one thing... I never buy speakers with foam surrounds any more. I
don't even look at them. I go straight for the butyl rubber or treated cloth
or whatever.

James. )



Nothing lasts forever, especially electrolytic caps. I don't think
today's are necessarily any better than good quality ones from the past.

I agree with you on foam rubber. Anything made out of foam rubber is on
a one-way journey back to goo and dust. The only question is how long
it will take. Don't expect the seats in any modern vehicle to still be
firm 10 years from now!

John



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Mark D. Zacharias Mark D. Zacharias is offline
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Default Fixed Sony TA-F555ES Integrated Amplifier Today

John Horner wrote:
James Lehman wrote:
Do you think that the electrolytic juice got cooked out?

I wonder what steps , if any have been taken to prolong the life of a
capacitor in the last 25 years.

I have several amps from the late 70's, early 80's.

I'd like to think that when you get something like that, it should
last forever.

I know one thing... I never buy speakers with foam surrounds any
more. I don't even look at them. I go straight for the butyl rubber
or treated cloth or whatever.

James. )



Nothing lasts forever, especially electrolytic caps. I don't think
today's are necessarily any better than good quality ones from the
past.
I agree with you on foam rubber. Anything made out of foam rubber is
on a one-way journey back to goo and dust. The only question is how
long it will take. Don't expect the seats in any modern vehicle to
still be firm 10 years from now!

John


Many caps are specifically designed NOT to last as long these days. Look in
a DigiKey catalog. Why else would a cap be rated at 1000 hours, but betters
ones rated at 2000 hours, etc?

I've seen radios at 65 years old which still had (some) good caps in them.


Mark Z.


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John Horner John Horner is offline
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Posts: 5
Default Fixed Sony TA-F555ES Integrated Amplifier Today

Mark D. Zacharias wrote:


Many caps are specifically designed NOT to last as long these days. Look in
a DigiKey catalog. Why else would a cap be rated at 1000 hours, but betters
ones rated at 2000 hours, etc?

I've seen radios at 65 years old which still had (some) good caps in them.


Mark Z.




Probably not aluminum electrolytics though.
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Jooel Jooel is offline
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Posts: 1
Default

Quote:
Originally Posted by John Horner View Post
I suspect that this is a common failure, so I am putting my fix out
there in the wild should anyone else want to use what I learned.

I purchased this amp in the early 1980s and have always liked it. It
was from Sony's high end specialty line at the time.

The problem was that the speaker protection circuit first started taking
a long time to kick in after power on and then eventually wouldn't kick
in at all. You can tell this by the fact that the LED in the volume
knob would stay red instead of turning green and the tell tale sound of
the speaker relays kicking in never happened.

I bought a scan of the schematics off the net. A bit of a rip off, but
I couldn't find free ones.

From the way the problem developed I figured that it was probably a
capacitor which had gotten old. Oddly enough, the circuit is split with
some components on the main board and some on the power supply board.

So, I replaced capacitors C404 (10 uF,16V), C405 (100 uF, 25V), C406 &
C421 (both 10 uf, 50 V NON-POLARIZED). Based on the circuit diagram I
suspect that C405 was the main trouble maker. It looks to me like R406
and C405 create the RC time delay which is an input trigger to the
HA12002 control IC. All of the caps I changed out are on the power
supply board. Be very carefull, those traces lift from the board very
easily. Even with care I buggered two of them up and had to do a bit of
add on wiring to make things right. For everything except the
non-polarized caps I was able to purchase replacement units with higher
voltage ratings. Maybe these will last 40 years .

Finally, I also switched the rear panel speaker impedance selector to
the 4-8 ohm setting. I found out that all this does is to lower the
voltage rails to the output stages and thus limit the peak current
availability. I never push this amp hard, and given it's age I feel
that pulling back on the output drive voltage a little might buy me some
extra lifetime.

Happy Listening!

John
Hello John,
Thanks for this guide!
I have the same amp, and I have a question for you regarding Amp Adjustment of BIAS and BALANCE. I simply cannot complete the procedure of adjustment this amp: I can't set BIAS to 100mV and also cant adjust the V-I board balance. So, the questions are, If you cam, please describe here the procedure of amp adjustment, or, even better if you could scan and send me Your service manual (or parts of it regarding to adjustments). Thank you very much! Regards.
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