Help required to repair Yamaha AVR RX-V667

[businessbysaud]

Also. Could the buzzing sound i heard be the mobile charger shorting?

 

[mbhangui]

This will cause the reciever to not turn on?

Like main on button does nothing. If i press tone+info+power. The reciever blinks red light twice. And then stays off.

Is this MOD culprit or something else is bugging?

1. The receiver will not turn on if the power supply has gone totally dead
2. One of the two capacitors C3701, C3717 go bad

If you have a multimeter, just check if there is voltage on the two wires that is coming back from the board (not the L3701 position, but the other position). The mod has not caused this problem. It looks like your SMPS IC went bad last time and the person put a cell phone charger to supply 5volts. Not a bad idea

 

[mbhangui]

Also. Could the buzzing sound i heard be the mobile charger shorting?

Yes. It looks like the mobile charger has gone bad. But only way to find that out is to use a multimeter and check the output on the two wires

 

[mbhangui]

Yes. It looks like the mobile charger has gone bad. But only way to find that out is to use a multimeter and check the output on the two wires. But be careful. YOu have live voltage on that board.

 

[businessbysaud]

I'll check the voltage and report back!
Thanks for the heads up!

 

[businessbysaud]

I wasn't able to check on my receiver due to office but i have noticed a few times that receiver starts on its on. and then turn off after some time.
I am not sure if it will be the MOD problem, something else is causing the system to go into safe mode(maybe). idk if its something shorting on the channels output or something flew inside the receiver. I am really confused.

i want to check the 5v output from mobile charger when the receiver is in running state and then on when its in safe mode unable to start. it will prove if its mobile charger mod that is causing the problem. if not then i will have to trace the problem.

also info+tone control + main zone is pressed. no error is shown. it just goes in A1-1 menu and then idk how to check what to search for in the menu. i referred to the troubleshooting guide but unable to understand any guideline. any help here too?

 

[businessbysaud]

I just figured something with multimeter. my aiwa center and front L/R speakers read 0ohms on the speaker binding post terminals. will they be shorting the amp? OH FFF
my remaining kenwood surround L/R and Surround back L/R read good resistance with multimeter.

if i am not wrong any 8ohm speaker should read beteween 5-7 ohm on dc resistance.

 

[spirovious]

I just figured something with multimeter. my aiwa center and front L/R speakers read 0ohms on the speaker binding post terminals. will they be shorting the amp? OH FFF
my remaining kenwood surround L/R and Surround back L/R read good resistance with multimeter.

If speaker shows 0 ohm that means its short.If its so,then Avr will shut down on volume increase.

 

[mbhangui]

I just figured something with multimeter. my aiwa center and front L/R speakers read 0ohms on the speaker binding post terminals. will they be shorting the amp? OH FFF
my remaining kenwood surround L/R and Surround back L/R read good resistance with multimeter.

if i am not wrong any 8ohm speaker should read beteween 5-7 ohm on dc resistance.

I'm asking a stupid question. I hope you didn't measure the resistance with the speakers connected to the AVR. You can connect the kernwood surround L/R to L/R and play it at low volume to see.

In general when the speaker terminals get shorted, the AVR displays "Speaker PRT"

 

[businessbysaud]

If speaker shows 0 ohm that means its short.If its so,then Avr will shut down on volume increase.

I thought that too. But its not the case. Some cross overs have inductors(i think those are called inductors not sure) which shows no resistance/open circuit.
My speakers have that kinda cross over which made me think my speakers were short. Opened and checked drivers and they are fine.

I'm asking a stupid question. I hope you didn't measure the resistance with the speakers connected to the AVR. You can connect the kernwood surround L/R to L/R and play it at low volume to see.

In general when the speaker terminals get shorted, the AVR displays "Speaker PRT"

It didn't show any. I MEAN "ANY" kind of error.

Btw i tested this for a good 3 days. Worked fine.
And now it shut down on me again. Right now i am running diffrent sets of speakers. Were only running stereo.

It seems like a fault in the avr now. I changed speakers to test the possibility and was convinced it was old speakers doing something to avr. But its something in avr for sure.


I want to know one thing. Video2 board is attached to a board below it.

I removed 3 screws(two on sides, one in back) to get access to the mobile charger(the mod) but i think video2 is linked through a port/some linkage with the board below.

I didn't want to force it so i left it as it is. Can i know how do i remove video2 board?

 

[mbhangui]

I want to know one thing. Video2 board is attached to a board below it.

Yes through a connector.

I removed 3 screws(two on sides, one in back) to get access to the mobile charger(the mod) but i think video2 is linked through a port/some linkage with the board below.

Correct.

I didn't want to force it so i left it as it is. Can i know how do i remove video2 board?

You just have to pull it up with a slight force. The board will come out of the connector on the board below. While fitting it back, you have to align the board male connector over the female connector and push it with a slight force.

 

[businessbysaud]

Yes through a connector.

Correct.

You just have to pull it up with a slight force. The board will come out of the connector on the board below. While fitting it back, you have to align the board male connector over the female connector and push it with a slight force.

This is the video2 board. What do you think of it?

 

[mbhangui]

This is the video2 board. What do you think of it?

The person who repaired it earlier has done a heart bypass for the board

That extra board has two white wires taking the mains power.
The two black wires have the 5.5 volts supply.

You can test it this way
Remove the power cord from the yamaha avr.
Insert that end of the power cord into this board. First put this board properly on a wooden board. Connect a multimeter leads to the two black wires.

Switch on the power supply and see what the multimeter shows. Be careful. Don't touch the board with bare hands with the power supply on.

EDIT: I can already see that you haven't disconnected the power cord. So you just have to connect the power supply and measure the voltage.

 

[businessbysaud]

The person who repaired it earlier has done a heart bypass for the board

That extra board has two white wires taking the mains power.
The two black wires have the 5.5 volts supply.

You can test it this way
Remove the power cord from the yamaha avr.
Insert that end of the power cord into this board. First put this board properly on a wooden board. Connect a multimeter leads to the two black wires.

Switch on the power supply and see what the multimeter shows. Be careful. Don't touch the board with bare hands with the power supply on.

EDIT: I can already see that you haven't disconnected the power cord. So you just have to connect the power supply and measure the voltage.

It's outputting this range: 5.12v - 5.15v

Should it be exactly 5.5 for the power to work?

 

[mbhangui]

It's outputting this range: 5.12v - 5.15v

Should it be exactly 5.5 for the power to work?

I think it is low. 5.5v is not exactly required but this power is required for the HDMI board which also has the microprocessor and does protection of the AVR. To confirm if it is being sensed as low, you will have to open the service manual and turn on the system diagnostics and get the PS1/PS2 value. This is from page 24 of service manual. You will have to read the service manual and learn how to turn on diagnostics. It is not difficult. Just read the manual

PS1 should be in the range 38-141
PS2 should be in the range 34-138

 

[mbhangui]

I guess the voltage you measured was with no load. When the board is connected, it will read much lower than 5.1 volts. The entire HDMI board and the digital boards depend on 5v and 3.3 volts. This are converted from 5.5v by dc-dc convertors. So if the voltage is low, the microprocessor may be turning on the protection.

 

[businessbysaud]

I think it is low. 5.5v is not exactly required but this power is required for the HDMI board which also has the microprocessor and does protection of the AVR. To confirm if it is being sensed as low, you will have to open the service manual and turn on the system diagnostics and get the PS1/PS2 value. This is from page 24 of service manual. You will have to read the service manual and learn how to turn on diagnostics. It is not difficult. Just read the manual

PS1 should be in the range 38-141
PS2 should be in the range 34-138

View attachment 71761
View attachment 71762
View attachment 71763

I took these pictures a week ago when the avr turned on for a short time.

 

[mbhangui]

I took these pictures a week ago when the avr turned on for a short time.

These are all normal. The problem is the AVR shuts off only when the voltage becomes abnormal and that's the voltage you need. This is what was happening with my AVR too.

There is a way to look at the Protection History. Can you see if there is anything in the protection history?

 

[businessbysaud]

These are all normal. The problem is the AVR shuts off only when the voltage becomes abnormal and that's the voltage you need. This is what was happening with my AVR too.

There is a way to look at the Protection History. Can you see if there is anything in the protection history?

if the avr starts up i can check. but if you can give me guide what to look for i might be able to get you the information

 

[mbhangui]

if the avr starts up i can check. but if you can give me guide what to look for i might be able to get you the information

You can do an easier thing. Refer to this photo of yours. There are two black wires coming from that extra SMPS board that the earlier repairer has fitted.

The wire that is almost bent at right angles near the solder point is the positive wire. The other wires that goes almost straight is the negative. Cut the wires. Solder a red coloured wire on the postive and a black wire on the negative. Desolder the two white wires that go to the makeshift SMPS. After this you can completely remove that extra SMPS board.

Take the red and black wires through the back outside the avr. Connect back the board, fix the screws etc.
Take any other chargers that you have. Measure the voltage. Select one that gives more than 5.3v. Cut the wires. Take a multimeter and connect the positive to the red wire and negative to the black wire. Wrong polarity can fry the HDMI board. So be careful here

Connect both the avr power plug and the mobile charger to the mains. This is what I did (2nd photo in this post). If the avr works flawlessly after this, then you just need to put another SMPS supply and it will save you lot of time of troubleshooting. If this doesn't help, then you will have to measure voltages at different test points and that is more complicated.