Help required to repair Yamaha AVR RX-V667

[mbhangui]

Does the AVR startup if you press "tone control + info" on the front panel together. Keep it pressed with two fingers and then press the power button using your other hand

 

[businessbysaud]

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.

View attachment 71769

View attachment 71770

will this separate 5v end up in ground loop? that might be problematic for the avr no? considering i am connecting to the AC supply on the wall instead of the AC that the board is supplying?

 

[businessbysaud]

Does the AVR startup if you press "tone control + info" on the front panel together. Keep it pressed with two fingers and then press the power button using your other hand

it doesnt start at all with 3 button config.
sometimes it starts but with no error at all!

 

[mbhangui]

will this separate 5v end up in ground loop? that might be problematic for the avr no? considering i am connecting to the AC supply on the wall instead of the AC that the board is supplying?

No. The power from this smps doesn't go to any audio circuits. It just supplies the HDMI and video board. Also what I suggested is only temporary. If that SMPS board is the culprit, you have two choices
1) Fit another smps (maybe of better quality). You can make a LPS too using LM317 IC and use that.
or
2) get the TOP254PN ic, remove inductor from some other SMPS and repair the yamaha's SMPS board.

 

[businessbysaud]

ok. lets say smps is not the culprit. what might be causing the problem? in hdmi or video board?

 

[mbhangui]

ok. lets say smps is not the culprit. what might be causing the problem? in hdmi or video board?

The power transistors in the amp circuit. Leaky capacitors on the amp board. Unlikely the HDMI or video board will cause this problem. Does the AMP remain on for long time if speakers are not connected.

But you can find the problem only if you manage to switch on the amp and put it in diagnostic mode and then play song and then see what gets recorded in the protection history.

 

[businessbysaud]

The power transistors in the amp circuit. Leaky capacitors on the amp board. Unlikely the HDMI or video board will cause this problem. Does the AMP remain on for long time if speakers are not connected.

But you can find the problem only if you manage to switch on the amp and put it in diagnostic mode and then play song and then see what gets recorded in the protection history.

so a new phenomenon is noticed so i am reporting it here before i start to fiddle into things.

i am gonna make it steps to fill the context.

1- i start the avr. works fine. then shuts off due to some reason.
2- doesnt start using main zone button. then i try 3 button start up. -> doesn't start
3- leave it for some hours; 3-6 hours
4- start it again using 3 button start up. -> this time it starts
4a- first relay is switched. its in A1-1 no protection screen display; 0-3 seconds after first switch on
4b- second relay is switched -> main amp turns on; 3-4 seconds
4c- on 7th second after 4a step the avr shuts off. main zone light blinks 2 time and doesn't wanna start. 3 button combo doesn't start the avr either.

if you understands this correctly this means that whenever the avr wants to start. or starts up. its first relay is switched on 3rd second. on 5-6th second 2nd relay switches. on 7th second the avr shuts itself off with red light blinking 2 times and doesn't wanna start anymore. until 3-6 hours have passed.

this means there is a current present in the system? maybe a capacitor that is holding a charge for 3-6 hours and till the charge in the capacitor is lost the avr doesn't wanna start again. high probability that this behaviour is caused by capacitor(if i still remember my 9th grade physics book).

thoughts?

edit; there is no speaker or any kind of wire attached except main AC wire that goes into AC outlet

 

[HIEND-Raja]

This symptoms look like dry capacitor in power supply. You need LCR meter.

 

[mbhangui]

so a new phenomenon is noticed so i am reporting it here before i start to fiddle into things.

i am gonna make it steps to fill the context.

1- i start the avr. works fine. then shuts off due to some reason.
2- doesnt start using main zone button. then i try 3 button start up. -> doesn't start
3- leave it for some hours; 3-6 hours
4- start it again using 3 button start up. -> this time it starts
4a- first relay is switched. its in A1-1 no protection screen display; 0-3 seconds after first switch on
4b- second relay is switched -> main amp turns on; 3-4 seconds
4c- on 7th second after 4a step the avr shuts off. main zone light blinks 2 time and doesn't wanna start. 3 button combo doesn't start the avr either.

if you understands this correctly this means that whenever the avr wants to start. or starts up. its first relay is switched on 3rd second. on 5-6th second 2nd relay switches. on 7th second the avr shuts itself off with red light blinking 2 times and doesn't wanna start anymore. until 3-6 hours have passed.

this means there is a current present in the system? maybe a capacitor that is holding a charge for 3-6 hours and till the charge in the capacitor is lost the avr doesn't wanna start again. high probability that this behaviour is caused by capacitor(if i still remember my 9th grade physics book).

thoughts?

edit; there is no speaker or any kind of wire attached except main AC wire that goes into AC outlet

Check all electrolytic capacitors on the amp board. The amp board also has the DC power supply.

 

[businessbysaud]

This symptoms look like dry capacitor in power supply. You need LCR meter.

specifically LCR meter or a multi meter will work?

Check all electrolytic capacitors on the amp board. The amp board also has the DC power supply.

by amp board you mean the Video2 board? can you specify which board you are referencing?

 

[mbhangui]

specifically LCR meter or a multi meter will work?

by amp board you mean the Video2 board? can you specify which board you are referencing?

No. The video2 board just has the relay to turn on the main power. The amp board is below the HDMI board. I think it is labelled MAIN(1) PCB. It also has the speaker outputs and heatsink. There are 5 large caps on this board (two are very large).

Remove the HDMI board to see inside. It will require you to disconnect few connectors and ribbon cables and screws. Be careful with the ribbon cable. Then use a torch light to see inside for any signs of leakage. This avr is not very old, so the caps shouldn't have dried up, but chances are one may have leaked.

 

[businessbysaud]

Tried using an alternative power supply to check if its the 5.5v issue but of no use.

Physically i see no burned caps or anything out of. The ordinary.

Next is to disassemble the avr and check the amp board. Right now its not powering up at all.

 

[mbhangui]

Tried using an alternative power supply to check if its the 5.5v issue but of no use.

Physically i see no burned caps or anything out of. The ordinary.

Next is to disassemble the avr and check the amp board. Right now its not powering up at all.

Is the standy red light near the power button glowing?

 

[businessbysaud]

Is the standy red light near the power button glowing?

Yes it is. 3 button diagnostic isn't powering up the amp anymore

 

[mbhangui]

Yes it is. 3 button diagnostic isn't powering up the amp anymore

Can you connect your tv to the HDMI out port and connect any video source to one of the HDMI input port (for e.g. connect it to HDMI1). If you have firestick, connect it to HDMI1 and ;power on the firestick. Switch on the AVR in standby mode (just the red led will glow). No need to press the power button on the AVR.

Play any video and on your remote select HDMI1 and see if video plays on TV. Then press HDMI2 and now your TV should go blank.

If all that is working, it means that your HDMI board and the microprocessor which does protection, etc are all working

 

[businessbysaud]

Can you connect your tv to the HDMI out port and connect any video source to one of the HDMI input port (for e.g. connect it to HDMI1). If you have firestick, connect it to HDMI1 and ;power on the firestick. Switch on the AVR in standby mode (just the red led will glow). No need to press the power button on the AVR.

Play any video and on your remote select HDMI1 and see if video plays on TV. Then press HDMI2 and now your TV should go blank.

If all that is working, it means that your HDMI board and the microprocessor which does protection, etc are all working

You're saying that the avr is recieving the signal from hdmi source and passing it to the tv even when its off?
Yea that will sort out digital board. Thats a good point to test.

Will the remote be recognized? Even when avr is turned off? I'll check in the morning

 

[mbhangui]

You're saying that the avr is recieving the signal from hdmi source and passing it to the tv even when its off?
Yea that will sort out digital board. Thats a good point to test.

Will the remote be recognized? Even when avr is turned off? I'll check in the morning

Yes, the remote will be recognized. That 5.5v supplies voltage for the digital board and the front panel. The digital board is always on, even in standby mode. The protection circuit is all in the digital board. It receives voltages from all other boards and other things like temperature and current.

 

[antoniodias]

Great job. Am happy your singing too. That too with the patience you have, I have to admire your DIY. GOD BLESS.

 

[businessbysaud]

Yes, the remote will be recognized. That 5.5v supplies voltage for the digital board and the front panel. The digital board is always on, even in standby mode. The protection circuit is all in the digital board. It receives voltages from all other boards and other things like temperature and current.

Ok so all hdmi ports are being recognized. That means digital board is fine.

Edit;
Adding a context
When we switch input from hdmi 1 to hdmi 2 the red light blinks 2 times.

The same blink happens when i press 3 button combo and then nothing happens. Just wanted to add it as an info to the thread

 

[businessbysaud]

There is absolutely no issue with db level. The power supply for the amps are different (unregulated 37 volts). All yamahas have multiple taps on the main transformer. However the main transformer is never connected to the mains directly. There is a standby power supply which uses 0.022 microfarad caps to bring down the AC voltage (C3701 and C3717) in the diagram. The most common problem with Yamaha AVRs I have come to know in various forums is that this design of using polypropylene caps rated for 630v is bad. They fail a lot and is the most common problem. In my case, the caps are fine. But have ordered better caps rated > 1000v to replace them. I have put the image of the caps below.
View attachment 63758

There is a SMPS circuitry which provides 5.64 volts and 3.3 volts for the digital board and the power on switch to function. The SMPS circuitry is based on TOP254PN IC (IC371 in the schematic diagram posted above). In the standby state, the digital board functions partially. e.g. If you have A/V sources connected to the HDMI ports, and a TV is connected to the HDMI out, you can switch the HDMI ports even when the AVR is in standby state. When you press the power switch button, it activates a relay on the standby power supply board and the main transformer starts getting power. Only when the main transformer gets power, the actual AMP gets activated. The amp boards also have 7812, 7912 and 7905 regulators which provide power for various signal processing boards.

In my case what is happening is that, even in the standby state, the amp switches off. It becomes totally off. The red led also doesn't light up and pressing the power button does nothing. To start the unit, I have to pull out the cable for around 20 seconds and connect it. Once I do that, the standby PS becomes on again and the push button starts functioning and the AVR works perfectly for few minutes till the power protection circuit gets triggered. The IC TOP254PN gets extremely hot.

how did you test your caps on the power board?
because my situation is similar to the problem stated here : https://sterlingit.com.au/yamaha-am...g-on-rx-v3800-rx0v1900-and-many-other-models/