Got this old Luxman L-215 in for repair. Complaint: One channel not working and a bad zener diode.
Took it home and sure enough, almost no audio on one channel, even so both LED's are on in the amp.
The repair:
1: LED mod. The Zener diode D112 was bad and left a black spot where it was installed. C133 was bad too and R153 was hot. I modified the circuit a little bit. Removed D112 altogether. Snipped R153 on the output side and added another 500 Ohm 2W resistor (all I had in the junk box) in series for combined 800 Ohms in total. Replaced C133 with a 100uF 50V capacitor out of a junk board. Took out the old lamp. Soldered a NSI45020 led driver to the pin on the function switch PCB, replaced the old bulb with a blue LED. Works great!
2: The audio repair: Both of the LEDs in the amp section were on, so the amp had to work. Basically I found tons of bad solder joints on the main and tone control board, dirty switches and variable pots.
Another one saved from the bin!
Took it home and sure enough, almost no audio on one channel, even so both LED's are on in the amp.
The repair:
1: LED mod. The Zener diode D112 was bad and left a black spot where it was installed. C133 was bad too and R153 was hot. I modified the circuit a little bit. Removed D112 altogether. Snipped R153 on the output side and added another 500 Ohm 2W resistor (all I had in the junk box) in series for combined 800 Ohms in total. Replaced C133 with a 100uF 50V capacitor out of a junk board. Took out the old lamp. Soldered a NSI45020 led driver to the pin on the function switch PCB, replaced the old bulb with a blue LED. Works great!
2: The audio repair: Both of the LEDs in the amp section were on, so the amp had to work. Basically I found tons of bad solder joints on the main and tone control board, dirty switches and variable pots.
Another one saved from the bin!