I have a SONY a home Cinema system (STR KSL5) which after about 2 mins
shuts down with the word PROTECT in the display screen. I have checked
all the speaker outputs and they are fine, no shorts. I have removed
all the speakers and the same problem occurs. The fan works so doesn't
seem to be an overheating problem. This PROTECT fault occurs even when
the volume is turned right down therefore not driving the amp. Anyone
have any ideas what might cause this fault? and how to rectify it?

Thanks

Davy H

"Davy H" wrote in message
ups.com...
I have a SONY a home Cinema system (STR KSL5) which after about 2 mins
shuts down with the word PROTECT in the display screen. I have checked
all the speaker outputs and they are fine, no shorts. I have removed
all the speakers and the same problem occurs. The fan works so doesn't
seem to be an overheating problem. This PROTECT fault occurs even when
the volume is turned right down therefore not driving the amp. Anyone
have any ideas what might cause this fault? and how to rectify it?

Thanks

Davy H


Sounds like an overheating (i.e., thermal intermittent) prob to me if it's
shutting down after 2 mins. That the fan is functioning doesn't preclude a
thermal defect in one or more components.

Get a can of component chiller (Freeze-It, et al) and spray each component
in the amp chain, beginning with the higher-current devices at the final
output stages. Allow the chilled part to warm up before proceeding to the
next one.

Alternatively, allow the unit to _fully_ cool, then manually heat components
with a soldering iron or finely tipped heat gun -- some techs use the
reverse (blow) mode of their desoldering guns -- within that 2 minute
window. Be very careful using this approach, as you can destroy a component
if you apply heat to it for too long or otherwise go beyond its designed
safety margins.

"Ray L. Volts" wrote in message
news:6v3Af.18398$sq.13135@trnddc01...

"Davy H" wrote in message
ups.com...
I have a SONY a home Cinema system (STR KSL5) which after about 2 mins
shuts down with the word PROTECT in the display screen. I have checked
all the speaker outputs and they are fine, no shorts. I have removed
all the speakers and the same problem occurs. The fan works so doesn't
seem to be an overheating problem. This PROTECT fault occurs even when
the volume is turned right down therefore not driving the amp. Anyone
have any ideas what might cause this fault? and how to rectify it?

Thanks

Davy H


Sounds like an overheating (i.e., thermal intermittent) prob to me if it's
shutting down after 2 mins. That the fan is functioning doesn't preclude
a thermal defect in one or more components.

Get a can of component chiller (Freeze-It, et al) and spray each component
in the amp chain, beginning with the higher-current devices at the final
output stages. Allow the chilled part to warm up before proceeding to the
next one.


This is what I get for usenetting when I'm barely awake. Obviously, if the
protection circuit has shut down the final stages, they won't warm up again
until the thermal fault is corrected, as power is likely not being applied
to them. You may have to give blanket coverage to several components at
once to bring the unit out of shutdown. Once you've determined the general
area at fault, you can hone in on the specific part(s) that is/are causing
the problem.

"Ray L. Volts" wrote in message
news:MB3Af.18399$sq.10742@trnddc01...

"Ray L. Volts" wrote in message
news:6v3Af.18398$sq.13135@trnddc01...

"Davy H" wrote in message
ups.com...
I have a SONY a home Cinema system (STR KSL5) which after about 2 mins
shuts down with the word PROTECT in the display screen. I have checked
all the speaker outputs and they are fine, no shorts. I have removed
all the speakers and the same problem occurs. The fan works so doesn't
seem to be an overheating problem. This PROTECT fault occurs even when
the volume is turned right down therefore not driving the amp. Anyone
have any ideas what might cause this fault? and how to rectify it?

Thanks

Davy H


Sounds like an overheating (i.e., thermal intermittent) prob to me if
it's shutting down after 2 mins. That the fan is functioning doesn't
preclude a thermal defect in one or more components.

Get a can of component chiller (Freeze-It, et al) and spray each
component in the amp chain, beginning with the higher-current devices at
the final output stages. Allow the chilled part to warm up before
proceeding to the next one.


This is what I get for usenetting when I'm barely awake. Obviously, if
the protection circuit has shut down the final stages, they won't warm up
again until the thermal fault is corrected, as power is likely not being
applied to them. You may have to give blanket coverage to several
components at once to bring the unit out of shutdown. Once you've
determined the general area at fault, you can hone in on the specific
part(s) that is/are causing the problem.


Bad joints on the output IC pins are very common on Sony A/V amps, and cause
the unit to go into protect like this

Arfa

Could be any of the 5 output amps, the sensing circuits or the CPU IC. You'll need a schematic to troubleshoot it. All 5 amps have a transistor Q401-Q405 2SA1162 (Protect) near them which monitor current flow to that output amp IC. These 5 all connect together to Q406 near IC321 on the main board.

Q406 should have +5V on the collector. That goes to pin 2 of IC321, out pin 3 of IC 321, then out connector D to Digital board, thru R112 to pin 53 of IC101 (CPU IC) on the digital board.

If you have +5V on pin 53, the CPU is bad. Part # 6-800-673-01 IC101 MB90553ABPF-G-209-BND. You won't, so you have to find out where the problem is.

"Davy H" wrote in message ups.com...
I have a SONY a home Cinema system (STR KSL5) which after about 2 mins
shuts down with the word PROTECT in the display screen. I have checked
all the speaker outputs and they are fine, no shorts. I have removed
all the speakers and the same problem occurs. The fan works so doesn't
seem to be an overheating problem. This PROTECT fault occurs even when
the volume is turned right down therefore not driving the amp. Anyone
have any ideas what might cause this fault? and how to rectify it?

Thanks

Davy H