Yamaha MCR-840 R-840 - The amplifier does not turn on, and the DVD does.

Hello

My five-year-old Yamaha Pianocraft MCR-840 has a problem. Initially, it happened that the R-840 amplifier segment did not turn on immediately. Only after some time did it startle and turn on. There is no problem with the DVD segment. Now, however, the amplifier cannot be turned on at all, it is completely dead. Before I start digging and measuring, I hope that someone has already had a similar problem and will give me some clues.

Any power measurements?

I checked that there is a live Graetz bridge at the input on the StandBy PCB. After the bridge, there is almost 400 V rectified. I got a schematic diagram and a diagram of this board. I will have to analyze step by step where the error is. The tower does not start with either the button or the remote control. Completely zero reaction.

Hello
If you have a schematic of the power supply board, I recommend checking the C13 capacitor and R14 resistor. I used the scheme from 69 pages SERVICE MANUAL R-840 / NS-BP300. Best regards and good service successes.

I have already repaired it, it was the capacitor that was damaged. This is typical for these amplifiers.

Dear Colleagues, you are "DEBESTS" - you helped me too, THANK YOU.
First, I set out ambitiously and scientifically with an oscilloscope in my hand. I was so confused that I postponed the work until the second day. And I remembered about the electrode and, of course, C13 - the job took 5 minutes.

Hello
I also had the above-mentioned problem. I admit that I am a total novice when it comes to electronics. I found a topic, bought a capacitor with parameters 22nF/630V and gave it to an electronics technician for soldering. Costs: PLN 2.5 - capacitor, PLN 10 - soldering.
Thank you and best regards.

Hello, I had similar symptoms - first the receiver did not turn on from time to time, then permanently. I sent it to a service center in Wrocław for repair - below is the receipt - because my soldering skills could cause irreparable damage . Unfortunately, when the amplifier came back on, the sound in the treble range is distorted - you can obviously hear the drums - something as if I was listening to a low-quality MP3. Dear colleagues, do you know what could have gone wrong? I will give the amplifier back, but it would be great if I could direct the service gentlemen - because I am afraid that they will not pay attention to the sound.

Hello
I also had this problem. I bought a capacitor (1.5 for 5 pcs + shipping). I soldered it and it works.
Thanks a lot!!!