Yamaha rx-v673 does not power on - relay not clicking and none led lit - Page 1
Forum section: electronics / repair

author: Roberts
author_rank: Contributor
timestamp: December 09, 2021, 08:26:40 pm
content: Hello eevblog, greeting from Serbia.I am troubleshooting one of these units and I thought it was going to be easy repair but...After checking all CPU voltages, capacitors, diodes and what not, I am beginning to think that CPU is maybe dead.p.s. only ic85 gets slightly warm at about 35 degrees if temperature on ir cam can be trusted for accuracy / and 50C when I press info+tone controll+main zoneAnd unit does consume 0.1w at first stage, but then it seems some process begins consuming 1w of power after one minute when main zone led begins to lit.Just found voltage on STBY_LED is 0.14v and goes to 0v when unit starts consuming 1w...What could be the problem?

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 10, 2021, 12:27:13 am
content: Check standby board first. Detailed information see pm.

author: Roberts
author_rank: Contributor
timestamp: December 10, 2021, 06:58:09 am
content: I have just checked CB375 has odd DEST voltage of 2.7 volts...That is all I can think of is wrong right now

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 10, 2021, 09:00:53 am
content: DEST voltage of 2.7 volts...This value should keep low 0.4V. Trace schematic and find out where it goes and check ALL components related to thisvoltage. In my memory, DEST means destination passingthrough mux and MAIN CPU. Check them ALL.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 10, 2021, 10:56:25 am
content: Sorry, I forgot to read pm. SMPS problem. Just Wait for mypm tomorrow. I will tell you how to fix SMPS in detail.All other voltages are off too... Do you mean NO voltages?She is very beautiful.173V is for 120V , while 330V is for 220-230V.One more question. In CB375, Did you get +3.3M 3.3VACPWR 3.3V & CPU_N_RST 3.3V? If yes, SMPS is OK.The problem is DEST.

author: Roberts
author_rank: Contributor
timestamp: December 10, 2021, 07:51:35 pm
content: Yes cb375 is all ok expect dest voltage...I have looked at DEST trace goes to IC76 Y5 pin... that is SN74LV4051A 8-Channel Analog Multiplexer and Demultiplexer...Voltages on this IC A,B,C is High, and if i am right this IC should by the truth table output 2.7volts on Y7 not on y5-dest...Or this is not he way these Ics work? Can someone correct me if I am wrong.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 11, 2021, 08:46:53 am
content: In normal condition, DEST is 3.026V, not 0.4V. I measured the voltage. Your value is lower. See photos. You need to find out why.I have looked at DEST trace goes to IC76 Y5 pin... that is SN74LV4051A 8-Channel Analog Multiplexer and Demultiplexer... There is a voltage supply here. Find it outand check voltage then check ALL resistors , caps related.

author: Roberts
author_rank: Contributor
timestamp: December 11, 2021, 12:52:27 pm
content: Vcc of IC76 is 3.3v...it is supplied properly...Maybe u can tell me how LCD is supplied with voltage because only thing i can get working is main zone led...Also i can not get PRY signal which switches on big transformer...p.s. maybe it is my multimeter but checking the CPU oscillator does not show 8mhz frequency. It shows fluctuations at 11Khz +-3Khz.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 11, 2021, 02:07:38 pm
content: see pmMaybe u can tell me how lcd is supplied with voltage because "only thing i can get working is main zone led..."Too bad, this means CPU is faulty.Also i can not get PRY signal which switches on big transformer... This is because CPU IS NOT working.At least makes DEST 3.026V is the only task.RESET amp first by a wire then use an oscilloscopeto check crystal 8MHz.It is 10:15pm Hong Kong time. I sleep now.

author: Roberts
author_rank: Contributor
timestamp: December 12, 2021, 07:27:26 am
content: After looking carefully at schematic I don't think that DEST voltage is fixed in every unit because if you look at resistor r3726 it is destination country dependent.I have checked everything u told me except frequency with oscilloscope and components do test ok. I will try oscilloscope test soon and I think there will be something wrong with frequency.By the way do you think that there is chance of corrupted EEPROM?

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 12, 2021, 09:28:44 am
content: After looking carefully at schematic I don't think that DEST voltage is fixed in every unit because if you look at resistor r3726 it is destination country dependent.Believe it or not, see photos. You can download it forcomparison. RXV767 service manual.By the way do you think that there is chance of corrupted EEPROM? Maybe. see pm for details.For oscilloscope check, reset signal and 8MHz xtal ,I will tell you tomorrowIf you want, rent a postbox. Give me address I will send youthis analog mux. I buy it from taobao and you replace it. Maybe 3.036V present. You can‘t know if it goes wrong until you replace it.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 12, 2021, 09:32:45 am
content: see photo. I can buy it at cheap price and send to you.

author: Roberts
author_rank: Contributor
timestamp: December 12, 2021, 03:18:37 pm
content: Thanks friend,but I do have it available for ordering.Osciloscope shows one 5v pulse at 125ns, so it looks like it is oscilating corectly.About analog mux - I have already switched them as there are at least 2 onboard and they behave the same...

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 13, 2021, 11:56:24 am
content: Thank you for your post .Your post let me know what DEST is.I finally know what DEST , destination is used for.I record a video for you to see what DEST is USED FORand will be pm you tomorrow.I will also record the waveform and reset signal for you.Please wait until tomorrow before 11:00 a.m. Hong Kong time.

author: Roberts
author_rank: Contributor
timestamp: December 13, 2021, 09:08:17 pm
content: Cheers

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 14, 2021, 04:02:52 am
content: Sorry for my late, brotherAfter study the schematic, I make a serious mistake. See pm and watch the video to troubleshoot.There is 99.99% for you to troubleshoot the amp if 1-6 is oK. 1-6 makes sure CPU can work properlyI want to say: fuck YOU yamaha forever. Waste my precious time to read the whole cpu schematic again due tochange of the cpu design. Fuck you yamaha all the time!!!!I have uploaded all videos for you.Be patient, watch them all, please, especially the fucking DEST.USE the switch to make your amp on and off during voltage measurement, see pm and photo.Borrow a mutimeter with freq. measurement to measure the xtal freq. (meter should be able to measure9.9999MHz freq. is more than enoughwhen freq. equals to 8MHz and amplitude are OK, crystal is ok.

author: Roberts
author_rank: Contributor
timestamp: May 02, 2022, 08:46:41 am
content: Ambrosia Heart still nothing after replacing components...Sorry for such a huge delay.

author: YADAN
author_rank: Newbie
timestamp: May 23, 2022, 06:19:14 pm
content: bonjourJ ai le meme problèmes avec Yamaha rx v673 pouvez vous envoyer les vidéos pour le dépannage merci beaucoupj.yadan.yahoo.fr