Sony TA-F55es doesn't complete power-on delay [audio amp]

N

Nautilus

Guest
I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
 
Get an ESR meter, and check all the caps in the amp. Considering the age, I
am sure you will find a number of them to be high in ESR. Without an ESR
meter, the only way to check the caps is by substitution. After changing all
the high ESR caps, you may find the unit to even sound better. This type of
cap problem was common in many of these amps.

The service manual may be available from Sam's Publications. Considering
the age, I would think the Sony parts department may no longer have this
manual as available.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...

I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
 
Could be a bad cap - but I think I've seen bad dual-FET's in these things.
Unless you're a pretty skilled tech type or just lucky I would think your
chances of repairing this yourself are slim.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...
I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
Click to expand...
 
"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...
I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
Click to expand...
Check the supply first. This is a switched mode supply and the output
capacitors (in the metal box) can be bad. Also the 2 large buffer capacitors
next to the endstage should be replaced. Further you can look for loose
solder joints, there were some in my TA-F55.

Also it could be wise to replace any other electrolyte capacitors. These
things always go bad after some years, and even faster in such hot
amplifier.

Good luck with it!

Al
 
schematic
www.datadart.com/jerry/TA-F555.PDF

hope it works for you


"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...
I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
Click to expand...
 
I just saw the posting of JR3611 and the circuit. To my surprise I see that
this amp has a normal power transformer?. I'm 100% sure that the TA-F55 here
has a switched mode powersupply... Is the 'es' on the end saying that it is
a complete different model? Weird.

Al
 
Thanks! Moderately skilled and often lucky. I'm great at
de-soldering, have a scope, and with the schemo now I can make a good
attempt. It's not my trade but experience goes back to when I built a
Heathkit TV (GR2000?). Last 'big' project was a couple years back - I
reversed engineered an RC toy to make a robot platform:
http://wombatlink.com/?250x02ibbw
See the PCB pics towards the bottom. It wasn't until after I reverse
engineered it that I found out RS has a manual available <g>.

It's probably not worth taking the amp to a real shop since it sounds
like all the electrolytics should be replaced to begin with. If you
think this model is worth that investment, let me know.

- Naut


On Mon, 2 Feb 2004 05:46:37 -0600, "Mark D. Zacharias"
<mzacharias@yis.us> wrote:

Could be a bad cap - but I think I've seen bad dual-FET's in these things.
Unless you're a pretty skilled tech type or just lucky I would think your
chances of repairing this yourself are slim.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...

I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
Click to expand...
 
Al,

Thanks for the pointers!


On Mon, 2 Feb 2004 19:49:47 +0100, "The Al Bundy"
<the_al_bundy@*^no-spam!^*hotmail.com> wrote:

"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...

I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!


Check the supply first. This is a switched mode supply and the output
capacitors (in the metal box) can be bad. Also the 2 large buffer capacitors
next to the endstage should be replaced. Further you can look for loose
solder joints, there were some in my TA-F55.

Also it could be wise to replace any other electrolyte capacitors. These
things always go bad after some years, and even faster in such hot
amplifier.

Good luck with it!

Al
Click to expand...
 
MANY Thanks!!!


On Mon, 02 Feb 2004 20:56:43 GMT, "JR3611" <jerry@datadart.com> wrote:

schematic
www.datadart.com/jerry/TA-F555.PDF

hope it works for you


"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote in message
news:xaednVWQ4s4CfIDd4p2dnA@comcast.com...

I have a Sony TA-F555es audio amp that does not complete the power-on
(speaker protection?) delay. It's a decent amp, I sure would like to
get it going again.

I've had it a long time and it had a consistent power-on delay (10
seconds?), then over a couple years it would take longer and longer
(1-10 minutes), and I noticed it would turn the speaker relay on more
quickly when it was off for only a day as opposed to a week. Now, it
won't come on at all.

This 'feels' like an electrolytic in a protection circuit has failed.
When in use the amp was babied, hardly ever run at 50% volume. Once
the amp came on it always stayed on. I'd bet the output transistors
are A-ok.

My first question ... is the power-on delay an RC circuit? Can anyone
point me to that section of the PCB or component ID #'s?

Second ... anyone have a schematic? Can you give me test points to
see the status of power-on and current-sense signals? The user
manual's block diagram just shows a protection muting block
immediately in front of the output connections.

THANKS!
Click to expand...
 
Oops, I see I have a typo in the subject line ... it's a "555", not a
55.


On Mon, 2 Feb 2004 22:11:15 +0100, "The Al Bundy"
<the_al_bundy@*^no-spam!^*hotmail.com> wrote:

I just saw the posting of JR3611 and the circuit. To my surprise I see that
this amp has a normal power transformer?. I'm 100% sure that the TA-F55 here
has a switched mode powersupply... Is the 'es' on the end saying that it is
a complete different model? Weird.

Al
Click to expand...
 
"Nautilus" <reply_in_newsgroup_thanks@example.com> wrote
news:jdadnb4Imq-7VIPdRVn-jw@comcast.com...
Oops, I see I have a typo in the subject line ... it's a "555", not a
55.
Click to expand...
That explains it :)
 
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