ZX475ti amplifier
Posted: Sat Sep 16, 2023 5:34 am
Hi, New here but have been trying to locate a service schematic for this old amplifier. There is a problem with the Front Left and Right Rear outputs, the rest of the amp works perfectly.
These outputs are low compared to the working section and the higher the volume the more distorted it becomes.
No indications of anything burnt, blown up or missing in the amp itself. All transistors tested fine and Op-amps are fine and the other components tested fine as well. These components were removed from the circuit board for testing to avoid any false readings.
I had the scope (Techtronic's) connected to it and the working outputs are showing a good sinewave (with a sinewave input to the amp) except one of the defective sections are showing a Sawtooth Waveform in one section. Thats where a schematic would be very very handy in identifying the section and the culprit causing the problem.
All the red LED's beside the transistors closest to the heat sink section are all working, the other row of red LED's are all off. The amp starts up fine, normal sequence and the blue LED's on the front cover all turn on.
When the amp is working normally on the good section, have it set up on the bench, operating at 12.5 VDC and can easily draw 10 amps of current with the volume turned up part way and no distortion or other problems noticed or heard.
Any assistance in the matter greatly appreciated.
These outputs are low compared to the working section and the higher the volume the more distorted it becomes.
No indications of anything burnt, blown up or missing in the amp itself. All transistors tested fine and Op-amps are fine and the other components tested fine as well. These components were removed from the circuit board for testing to avoid any false readings.
I had the scope (Techtronic's) connected to it and the working outputs are showing a good sinewave (with a sinewave input to the amp) except one of the defective sections are showing a Sawtooth Waveform in one section. Thats where a schematic would be very very handy in identifying the section and the culprit causing the problem.
All the red LED's beside the transistors closest to the heat sink section are all working, the other row of red LED's are all off. The amp starts up fine, normal sequence and the blue LED's on the front cover all turn on.
When the amp is working normally on the good section, have it set up on the bench, operating at 12.5 VDC and can easily draw 10 amps of current with the volume turned up part way and no distortion or other problems noticed or heard.
Any assistance in the matter greatly appreciated.