Yamaha RX-A2010 Front Display Garbled/Corrupted After Loud Volumes

[8bit_coder]

Hey all,

My Yamaha RX-A2010 very recently began having weird corrupted characters on the front display. This only happened right after I turned the volume very high up (-2.0 dB) for a short period of time. It always seems to be that certain segments accidentally become "linked" with other random ones, causing them to partially display what's on the other ones in a very broken way. It's completely random when it happens and how severe the issue is.

Here's a video of the problem: https://cdn.discordapp.com/attachments/889966457226682458/1107840178543939684/20230515_181906.mp4

It's solved by turning the receiver off and back on again. But it comes back in very minor glitching on the source name segments (the smaller ones in the top left of the screen) after the receiver has been on for a while (this image depicts a more severe case but my point still stands):



I suspected that this could be a voltage regulator near the display controller going bad since the issue mainly pops up at high volumes, but I checked the voltages leading to the display controller and they all match up with what they're supposed to be. The display on this receiver is a VFD with a built-in controller that seems to operate on SPI (judging by the pin labelled MOSI connected to it). I've checked all of the display's segments through the receiver's diagnostics and all of the elements seem to be working fine on their own.

FWIW, I've managed to reproduce the issue by shorting the Chip Select pin of the VFD controller to ground. I've already reconnected all of the ribbon cables leading to the VFD's board and I don't think this is the issue, but I thought it would be worth mentioning.

Here's the link to the service manual: https://elektrotanya.com/cgi-bin/download2.cgi?dk=h657lly0kukadddpnqc97lqsfgpjf48fkhy18lk4j67pzah0&fid=296141&file=yamaha_rx-a2010_rx-v2071.pdf

I'm fairly good with electronics repair so I'll try anything if it helps.

Any and all help is appreciated. Thanks!

[NiHaoMike]

Try gently knocking on the case to check if there's a loose connection somewhere. Also check the capacitors in the power supply.

[8bit_coder]

Already tried both of these. Knocking / hitting the receiver on any part does nothing to fix the issue, and the power supply caps all seem good. All the voltages are reading correctly and they're not sagging when turning it up really loud.

Also, I don't think it's capacitors since I watched my wall voltage dip from 119 to 114 with the receiver at near full blast and the outputs at test points were rock solid 5.5v and 3.3v. The power supply seems to be working perfectly fine. I even checked the voltage regulators around the display and they were all functioning correctly too.

[David_AVD]

I repaired a Yamaha RX-V series last week that had a bad 4 pin SMD regulator on the display PCB. It supplies 3.3V to the VFD driver.

You can get them from Mouser, but I pinched one off another board to complete the job faster.

The symptom on the one I repaired was the display not running at all, or only for a short while then the scanning stopped and one or more segments lit brightly.

[8bit_coder]

Very interesting that you note this. I actually suspected the exact same regulator you're talking about, a regulator that takes in 5.5v and spits out 3.3v that goes straight to the display's VDD. However, once I checked it with a multimeter, neither the input voltage nor the output voltage budged an inch when the receiver was under extremely heavy load. Good guess though!