PS48 Bose sub & head unit schematic / advice please.

[zen]

PS48 is model for sub & where i suspect issue lies .

CD head unit seems to run ok , & can take a line out signal into an amp with audio present .

Can't seem to measure any voltages at secondary side of PSU within SUB unit .

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

Yep ,primary side requires a rebuild .

First on the list Q101 & Q102 ( ST Electronics P9NB50FP ) . Both S/C , which doesn't surprise me considering the amount of glue across their respective pins that had turned a dark brown colour & no doubt become conductive .

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

Also replace the following .

U101 , ST Electronics L6598D

R101 , 10R

R103 , 10R

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

C119 ( 470NF ) has a leaky resistance reading of 10K

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

D150 , marked KJJN9 , which is in fact BAV70 .

Contains two diodes with a common cathode .

One of them measuring leaky & become a 2 way street .

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

Q104 , marked K3NN7 , which is an MMBT3906 has a low reading of 45R at collector / emitter junction .

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

Q103 , marked K72 L7 , O/C .

Only mentioned on parts list & schematic as being an N-CH-FET .

Spotted a thread on another forum stating that it's type 2N7002

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

Also stated on thread found that the opto's can go leaky .

Not taking any chances therefore replaced U102 & U103 , both type CNY17F-1

[zen]

Re: PS48 Bose sub & head unit schematic / advice please.

WOW ,what a mission .

All working & on test .