Hello everyone,
New to this forum but glad to be here. I purchased a defective Yamaha RX-V2067 2 years ago, hoping it's an easy fix. Sadly it has a DC_PRT too high issue (~200-220 at all times) that triggers protection. I have a friend that repairs electronics but because he did not have enough time, we kinda kept delaying the search for what could be wrong with the amplifier. Today, we took it apart again, removed both (not sure if it's the correct term) power amplifiers/sound amplifiers that driver each channel. So this way, only the logic boards and power supply remained connected. We discovered that it still triggers the protection, so we are pretty sure that it's not those that are faulty.
We traced that the issue starts with IC902 pin 1 that has the high value. If we used a resistor between pin 1 and ground (pin
the issue stops and it does not trigger protection anymore, but if we connect the power amplifiers again, there is a buzzing (probably voltage) coming through on all channels (into a speaker). IC902 pin 1 and 3 do not have the values the service manual states, and we also checked LMT_DC that is created by Q9010 + Q9011 and on the emitter side of Q9010 the voltage is 0 instead of 0.3.
Sadly we could not continue with the search for the issue today, but I would like to ask your opinion on what should we be looking for. Are there specific things that tend to break that may cause these symptoms? We did not check R9008 that is the resistor between the LMT_DC and DC_PRT because we could not find it and we ran out of time.
Thanks a lot and have a great day!