yamaha RX-V579 dead no power - Page 1
Forum section: electronics / repair

author: dbgeek
author_rank: Newbie
timestamp: January 15, 2025, 12:48:56 pm
content: Hi,bought a dead RX-V579 ,do get 5.5 volts from rail but no +3.3 volts on the rail that powers Relay ,service manual that I downloaded is incorrect as it shows voltage checks for a non -US receiverhttps://elektrotanya.com/yamaha_rx-v579_tsr-5790.pdf/download.htmlhave replaced both 47nf caps C5408,C5409,online folks have said that it may be C5405 .Not sure how to troubleshoot this issue.Fact that 5.5 volt rail is working tells me that Primary transformer on power supply is working only issue is to get +3.3 volts working for PRY to work I guessThanks

author: tom66
author_rank: Super Contributor
timestamp: January 15, 2025, 01:13:03 pm
content: I had this with my old Yamaha (RX-V457) and ultimately concluded it was a dead microcontroller, so it went to the e-waste pile in the sky. Check the processor board is regulating the 5.5V down to 3.3V for the microcontroller. My 3.3V supply was present but all signals on the MCU were dead, including relay on signal, I later found online this does occur sometimes, perhaps power surge damage or bad flash cells degrading. In theory a new board could fix it, but I couldn't source one. The RX-V579 is a much newer generation though so you may have better luck, good luck either way.

author: FIXITNOW2003
author_rank: Regular Contributor
timestamp: January 16, 2025, 07:27:40 am
content: https://www.hifiengine.com/hfe_downloads/download.php?yamaha/yamaha_rx-v579_tsr-5790_service_en.pdf

author: dbgeek
author_rank: Newbie
timestamp: January 17, 2025, 03:49:16 am
content: sorry I am not able to download as hifi site disabled new user creation, I accidentally disconnected connector from micro and after connecting I do see 3.3M but still cannot power up the system.when I tried jumper on relay I do hear click on amp relay but nothing happens, should I be checking any other part/s for voltage as I am guessing issue is with not powering relay on standby and amp/regulator needs to checked

author: tom66
author_rank: Super Contributor
timestamp: January 19, 2025, 10:18:54 pm
content: Can you upload that PDF directly? I can't access it.

author: FIXITNOW2003
author_rank: Regular Contributor
timestamp: January 20, 2025, 08:04:35 am
content: its 18 meg SO TOO LARGE FOR HERE pm me your email address

author: MathWizard
author_rank: Super Contributor
timestamp: January 21, 2025, 06:05:38 pm
content: What's missing, the logic control signal to the BJT's for the PWR ON relay ? Or the Vcc that would be on C2206 in that 1st manual ? Where's that Vcc com from, some 3-pin regulator or little circuit from a StandBy rail ?I'd start with it turned off, with a DMM I'd check over all the power rails, and Vcc rails on each board. Then I'd make sure the relay circuit itself is working, I might discount some of the boards or cut power to sections , just until I was sure the PSU section is ok.So why did you get the Stereo? For fun, profit, learning experience, /etc ?I bought 1 used stereo last winter, and it had problems on day 1, but I kept it for fun and to learn more about them. Some of the input chips on mine are acting up, and /or the main MCU. So I'm programming my own MCU to help out, when my stereo doesn't do what it should be doing.

author: dbgeek
author_rank: Newbie
timestamp: January 31, 2025, 11:57:10 pm
content: was able to get receiver powered up by chance, when I push info and tone control button while plugging 5 volt rail from standby power to ldmi board, receiver comes on and goes to USB UPDATE mode ,and I can get it to same state 3 times.will try USB UPDATE with firmware later and report back,weird guessing a USB UPDATE could have been attempted by the guy who sold this to me and could have bricked or flash is corrupt somehow!

author: dbgeek
author_rank: Newbie
timestamp: February 06, 2025, 12:14:19 am
content: I am able to power when I unplug and plugin 5 volts rail from standby connector and receiver goes into standby state with led on and with remote can power on and get all the functions working display works,but nothing from front panel works(buttons ) except volume control knob and direct button(which is Key2 etc) and when I push buttons receiver shuts down if press net or radio button only thing that works is the info button, when powering up (with volt rail plug in time ) sends receiver to usb update mode and I was able to update firmware as well.but only was to get this is via the 5 volt rail method.not sure if microprocessor is acting up or something is shorted!

author: wraper
author_rank: Unknown
timestamp: February 06, 2025, 12:28:52 am
content: QuoteCheck/replace electrolytic capacitors in standby PSU if it's SMPS, especially small capacitor on primary side on PWM controller VCC.