SONY "PROTECT" MHC-EC909iP

[Pick]

SONY
MINI HI-FI COMPONENT SYSTEM
MHC-EC909iP

Unit normally displays "PROTECT", if speaker wires "cross" or touch one another. After resolving this "wire issue", unplugging the unit & then plugging it back in then resolves the issue.

However, this time is different.

I've unplugged all speaker wires, from the back of the unit, and "PROTECT" error continues to display.

I notice the unit "Clicks", a certain number of times, while powering on (before finally deciding to display "PROTECT"). Perhaps the number of times the unit "clicks", before Powering On, might indicate the problem / help to troubleshoot the error? Does anyone know where I might find more information about this "troubleshoot clicking"?

Any help is greatly appreciated.

Thanks!

-Pick

Josh Pickeral
[mod edit: E-Mail removed, please reply within this thread or use private message (conversation) if necessary.]

 

[73's de Edd]

Sir Josh Pickeral . . . . . . . . . . .

The clickee- clickee noises that you are hearing are probably the effect of the overload condition causing relay
RY701, in disengaging your amp power connection to the right and left channel speakers as well as RY801,
disengaging connection to your B E E E G center speaker.
One certainly does not want upwards of + or - 35 VDC at 500 + ma hitting the speaker voice coils.
Touching the top cases of the two relays should let your sense of feel, confirm if they are the source of the clicks at power turn on / ons.

The power amps are potted power modules IC604 for the R and L channels and IC606 for the center
channel amp.

A DC sampling is taken from the Audio output pins of the respective power amps (pins 4-5-6-7) and is fed to OVERLOAD detection circuitry, which then trips those relays to speaker disconnect in case of DC voltage coming from a defective POWER AMP module.
Marked on parts designator for an IC604 is being STK433-870-E
Marked on parts designator for an IC606 is being STK433-070-SE

You initially gain chassis access to the two large potted modules and use metering of voltage in the DC mode and use meter ground to pin 10 and then see which of the pins 4-5-6-7 of either modules have in excess of probably a minimum of 1 VDC, which would then trip your overload detection circuitry.
(Such as you are probably experiencing.)


What else could you possibly need now ?

RELEVANT TECHNO REFERENCING . . . . .



73's de Edd
.....

 

[WHONOES]

Sounds like you have shorted an output once too often and wrecked an amplifier module. You probably need to get in there and do some measurements like the DC offset voltage of the amps.