Hi All
I have a Technics Midi system from the early 1990's (all that remains of my first paycheck after graduation) currently sitting on my bench. It started playing up a while back, I took it down to a service agent but he advised that it wasn't worth his time to fault find and repair so it has gathered dust under the desk but now is the time to give it another look.
The protection cut out is tripping the speakers, in some cases as soon as it is turned on while in others it runs for a couple of hours before failure. Yesterday I spent most of the afternoon rocking to the 80's at 50%+ volume no issues before tripping.
Turning the volume to zero, turn power on, slowly increase volume, if speakers 'Pop' and protection trips, turn off and try again.
I have followed the Service Manual instructions and disassembled the unit on the bench so it can still be used.
http://elektrotanya.com/technics_su-x102_sm_1.pdf/download.html
My reading on the internet has indicated that Caps or Dry Joints tend to be an issue with this model. The main board looks clean, no discoloration or leaking Caps, the through whole solder joints appear secure.
Looking through the schematic I have traced a few of the voltage lines and the only thing I noticed was the that higher voltage lines to the Power Amp look low;
Pin Spec As Read
1 0v 0v
2 38.7 37.3
3 -39.4 -37.5
4 0
5 14.2 13.3 (starts at 14.2 but voltage drops away as reading )
6 0
7 4.4 4.3
8 -14.8 -14.3
9 0 0
I have also found that as I read the 0V signal pins (10, 11 & 13, 14) I get an interference buzz except reading pin 14 trips the protection every time.
I am open to any and all suggestions on how I should best fault find to resolution.
Regards
Dave
I have a Technics Midi system from the early 1990's (all that remains of my first paycheck after graduation) currently sitting on my bench. It started playing up a while back, I took it down to a service agent but he advised that it wasn't worth his time to fault find and repair so it has gathered dust under the desk but now is the time to give it another look.
The protection cut out is tripping the speakers, in some cases as soon as it is turned on while in others it runs for a couple of hours before failure. Yesterday I spent most of the afternoon rocking to the 80's at 50%+ volume no issues before tripping.
Turning the volume to zero, turn power on, slowly increase volume, if speakers 'Pop' and protection trips, turn off and try again.
I have followed the Service Manual instructions and disassembled the unit on the bench so it can still be used.
http://elektrotanya.com/technics_su-x102_sm_1.pdf/download.html
My reading on the internet has indicated that Caps or Dry Joints tend to be an issue with this model. The main board looks clean, no discoloration or leaking Caps, the through whole solder joints appear secure.
Looking through the schematic I have traced a few of the voltage lines and the only thing I noticed was the that higher voltage lines to the Power Amp look low;
Pin Spec As Read
1 0v 0v
2 38.7 37.3
3 -39.4 -37.5
4 0
5 14.2 13.3 (starts at 14.2 but voltage drops away as reading )
6 0
7 4.4 4.3
8 -14.8 -14.3
9 0 0
I have also found that as I read the 0V signal pins (10, 11 & 13, 14) I get an interference buzz except reading pin 14 trips the protection every time.
I am open to any and all suggestions on how I should best fault find to resolution.
Regards
Dave
).
