Sony STR-DE615 : Indicates PROTECTOR

R

Russ Wright

Guest
Recieved with the main fuse blown. No text display.

Replaced MN2488 (Q556) and MP1620 (Q557)outputs plus 2SA988 (Q558)

Now the unit indicates PROTECTOR after a few seconds, What may I have
missed. Any suggestions ,

Thank You


Russ
 
Open resistors, bad 2SA988 protection "gate" transistors, open emitter
resistor, DC offset due to bad driver IC, who knows?

Mark Z.


"Russ Wright" <russwright@magma.ca*NO*SPAM*> wrote in message
news:VWydnde7-O08fxCiU-KYjQ@magma.ca...
Recieved with the main fuse blown. No text display.

Replaced MN2488 (Q556) and MP1620 (Q557)outputs plus 2SA988 (Q558)

Now the unit indicates PROTECTOR after a few seconds, What may I have
missed. Any suggestions ,

Thank You


Russ
Click to expand...
 
Russ Wright wrote:
Recieved with the main fuse blown. No text display.

Replaced MN2488 (Q556) and MP1620 (Q557)outputs plus 2SA988 (Q558)

Now the unit indicates PROTECTOR after a few seconds, What may I have
missed. Any suggestions ,

Thank You

Russ
Click to expand...

First thing to do is make some measurements to find out what's
happening. Chances are you'll see a large DC offset on the emitter
resistors. In any amp, this is due to any number of problems such as
open resistors, or bad driver transistors and ICs. Use the good channel
as a reference to see where the DC offset is coming from, or to swap
driver ICs and other parts.
--
Andy Cuffe
baltimora@psu.edu
 
Russ Wright wrote:
Recieved with the main fuse blown. No text display.

Replaced MN2488 (Q556) and MP1620 (Q557)outputs plus 2SA988 (Q558)

Now the unit indicates PROTECTOR after a few seconds, What may I have
missed. Any suggestions ,

Thank You

Russ
Click to expand...

Do you get a raster when you turn up the G2 control?
--
Andy Cuffe
baltimora@psu.edu
 
Did the new transistors short? Did you check the emitter resistor? Did it
run with the transistors out of the circuit? Did you resolder several dozen
bad solder joints?

Leonard Caillouet

"Andy Cuffe" <baltimora@psu.edu> wrote in message
news:3F8E0228.6E2C@psu.edu...
Russ Wright wrote:

Recieved with the main fuse blown. No text display.

Replaced MN2488 (Q556) and MP1620 (Q557)outputs plus 2SA988 (Q558)

Now the unit indicates PROTECTOR after a few seconds, What may I have
missed. Any suggestions ,

Thank You

Russ


Do you get a raster when you turn up the G2 control?
--
Andy Cuffe
baltimora@psu.edu
Click to expand...
 
As suggested by others, I have found an open Emitter resister , that is used
with the shorted output transistors that I changed earlier. I will replace
this, I also found doing some web searches about insuring ALL ground screws
are in place.
I have not resoldered any "cold solder joints" As I was not looking that
way, something else to check

Thanks , I will follow up as I go.

Russ


"Leonard Caillouet" <lcailloNOSPAM@devoynet.com> wrote in message
news:npnjb.77316$AH4.37324@lakeread06...
Did the new transistors short? Did you check the emitter resistor? Did
it
run with the transistors out of the circuit? Did you resolder several
dozen
bad solder joints?

Leonard Caillouet

"Andy Cuffe" <baltimora@psu.edu> wrote in message
news:3F8E0228.6E2C@psu.edu...
Russ Wright wrote:

Recieved with the main fuse blown. No text display.

Replaced MN2488 (Q556) and MP1620 (Q557)outputs plus 2SA988 (Q558)

Now the unit indicates PROTECTOR after a few seconds, What may I have
missed. Any suggestions ,

Thank You

Russ


Do you get a raster when you turn up the G2 control?
--
Andy Cuffe
baltimora@psu.edu
Click to expand...
 
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