SONY - STR-GX900ES - FLASHING "PROTECTOR"
Errol gomes
flashing "protector".
I have checked all ground screws, weak solder joints, etc. infact I
Replaced the main amplifier IC's - STK350-230, and the protection
transistors - 2SA988, and the protector switch transistors - 2SC1841,
AND 2SD774, along with some diodes - 1N4148M.
now the amp section is fine but the unit will still not come out of
protection, now I know, you may ask how do I know that the amp is
fine, heres how.
When a working unit (same model-str-gx900es) is turned on the main
relay on the main amp circuit board energises, and makes contact, so
to test the amp this is what I did, I took off the plastic cap off the
relay, and exposed the contacts(L & R Speaker), then I turn on the
unit and before the protector message hits the screen and unit, I
manually energise the relay contacts(with my fingers), and I get
clean, clear - distortion free (FM) sound from both left and right
channels, until protection hits and then the music stops, and all is
silent with the message " protector" flashing on the display.
now I would think the amp is fine as I am getting sound from all
channels, but what I do not know is what I am overlooking, or what is
still causing the protection fault.
I would really appreciate any and all the help that I can get to have
this problem solved, if you do have any advise, or suggestions,
questions, statements etc. Please do drop me a line at :
cli...@hotmail.com
thanking you
Errol
(cli...@hotmail.com)
Sofie
Did you measure the DC offset on the speaker rails (without load) ? ?
Even a small amount will cause the protection circuitry to trigger.....
otherwise you may have to troubleshoot the protection circuitry itself.....
strange.... that all 3 units have the same symptoms ...... could be
different faults for each, however. Happy troubleshooting.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
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Errol gomes <cli...@hotmail.com> wrote in message
news:d306878e.01110...@posting.google.com...
Errol gomes
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hi sophie, thanks for your advice, I do have a question though, you
say I should measure the DC offset on the speaker rails, by this I
guess you mean check for DC current on or at the
speaker(Left,Right,Center,Rear) terminals.
Is this correct or have I misunderstood you, please do let me know(I
guess there should be no DC current leakage at the speaker terminals
at all.
Is there any way that I can bypass the protection circuit at all so
that I can troubleshoot the reciever, by turning it on without it
going into the protection mode at all, and finally here is something
else That I tried - I tracked down the protection circuit to a
microprocessor IC(IC150 - P/N# HD6433258B55F) on the surround board,
the protection circuit connects to pin number 12 on the MICROPROCESSOR
IC, which is designated as "PROTECTOR SIGNAL INPUT" On the service
manual, now, hoping to bypass the protection message & circuit, I
thought I would disconnect this single pin (protect signal input) from
the circuit board, so that, When I turn the unit on it comes on and
does not go into protection. all said and done I unhook(disconnect )
this pin from the circuit board, and then turn the unit on, and guess
what, this is really weird - the unit still goes into protection mode.
now my question is simple, even though I have disconnected the
"protect signal in" terminal of the microprocessor, how is the unit
still going into protection
Please, any and all help will be much appreciated, as I am almost out
of options, and would like to keep the cost of replacing parts as low
as possible.
Please do advise.
P.S. I shall be checking for DC current at the speaker terminals
today, and see what I find.
Once again, thank you for your much appreciated advice and input.
thank you
Errol
(cli...@hotmail.com)
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THIS MESSAGE BELOW WAS POSTED ON NOV.5TH 2001
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cli...@hotmail.com (Errol gomes) wrote in message news:<d306878e.01110...@posting.google.com>...
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