PROTECTION ISSUE SOLVED! NOTE TO EVERYONE: PAY ATTENTION TO YOUR REPLACEMENT TRANSISTORS! AN NPN TRANSISTOR WON'T WORK IN A PNP SPOT! THANKS TO @petehall347 !
Picked up an SX-950 which was guaranteed, in person, to my face, to work great. Pretty excited, my first 'big' Pioneer. Of course, it does not work at all.
First observation was that it was not coming out of protection. Other observations are that none of the speaker lights ever light up (A/B/C), and also that the source lights (Phono / FM / AM / Aux / etc) light briefly and quickly fade away.
I saw weird protection circuit readings. So, I replaced all caps & transistors in my power supply and my protection circuits. What did I use for replacements? Well, I followed the parts lists that are posted around here. I am (pretty) sure that all my transistor B/C/E and capacitor +/- orientations are correct. Will be confirming.
Unfortunately, I am getting wonky readings from my power supply, and wanted to post here for help / commentary as I go about scratching my head about it.
So here are the power supply (AWR-101) readings I have done so far:
R1, R2, and R20 all test OK
D1, D2, D3, D4 all test OK
Fuses all test OK
Outputs
Pins: Pin / Ref / Read
6, 7 51.5V 14.75V BAD
8, 9, 10 36.5V 10V BAD
11 28V 6.5V BAD
13 -13.5V -13.3V OK
14 -51.5V -51.5V OK
15 -19V -19V OK
4, 5 13.9V 2.8V BAD
2, 3 5.4V ?Oscillates? VERY BAD
Transistors:
Pins: B C E
Q1 15V 66.9V 14.4V WRONG B & E
Q2 -52.1V -67.2V -51.6V OK
Q7 6.8V 7.2V 6V ALL WRONG
Q3 4V 15.2V 3.4V ALL WRONG
Really, I'm confused as to HOW I can be getting such a bad reading at the Base of Q1 with R1 & R2 testing properly as well as D1-D4.
Picked up an SX-950 which was guaranteed, in person, to my face, to work great. Pretty excited, my first 'big' Pioneer. Of course, it does not work at all.
First observation was that it was not coming out of protection. Other observations are that none of the speaker lights ever light up (A/B/C), and also that the source lights (Phono / FM / AM / Aux / etc) light briefly and quickly fade away.
I saw weird protection circuit readings. So, I replaced all caps & transistors in my power supply and my protection circuits. What did I use for replacements? Well, I followed the parts lists that are posted around here. I am (pretty) sure that all my transistor B/C/E and capacitor +/- orientations are correct. Will be confirming.
Unfortunately, I am getting wonky readings from my power supply, and wanted to post here for help / commentary as I go about scratching my head about it.
So here are the power supply (AWR-101) readings I have done so far:
R1, R2, and R20 all test OK
D1, D2, D3, D4 all test OK
Fuses all test OK
Outputs
Pins: Pin / Ref / Read
6, 7 51.5V 14.75V BAD
8, 9, 10 36.5V 10V BAD
11 28V 6.5V BAD
13 -13.5V -13.3V OK
14 -51.5V -51.5V OK
15 -19V -19V OK
4, 5 13.9V 2.8V BAD
2, 3 5.4V ?Oscillates? VERY BAD
Transistors:
Pins: B C E
Q1 15V 66.9V 14.4V WRONG B & E
Q2 -52.1V -67.2V -51.6V OK
Q7 6.8V 7.2V 6V ALL WRONG
Q3 4V 15.2V 3.4V ALL WRONG
Really, I'm confused as to HOW I can be getting such a bad reading at the Base of Q1 with R1 & R2 testing properly as well as D1-D4.
Last edited: