Another Yamaha

[No1baggiesfan]

My Yamaha RX-V671 has an illness
I think we had a power surge/outage a couple of days ago as my PS4 informed me that I hadn't turned it off properly, it's usually left in rest mode to charge the pads, anyway, amp turned itself off when my wife turned it on, and then again, so I tried, same thing, I reset the amp, checked all speaker cables, then powered it back on, it worked fine for about 45 mins then switched off again.
Diagnostic mode gives the error: PS: PRT 135 H
I also see a fluctuating value in p1-2 diagnostic: PS 160/129 which suggests a high volt error somewhere ?
No C405 on this amp lol
I have the service manual, but wiring diagrams have never been my strong point :/

[No1baggiesfan]

Re: Another Yamaha

Nobody ?

[redwire]

Re: Another Yamaha

Why would someone repeat the work others have done, reading the schematics, interpreting 160/129 etc.

You've cross-posted the same repair to at least two other forums:
https://www.eevblog.com/forum/repair/yamaha-amp-woes/
http://repairalmostanything.com/thre...-yamaha?page=1

Perhaps you should finish work with those forums.

[No1baggiesfan]

Re: Another Yamaha

Because I received no replies on one forum and only a couple on the other, is it wrong to ask nowadays ?

[CapLeaker]

Re: Another Yamaha

It's never wrong to ask a question, but if you want to get folks more interested in your case, maybe you should update this thread on what you know, or have figured out in the mean time. You also didn't attach the service manual nor pictures, so I am sure not too many folks are going to spend their time on it like this.
I've seen your posts on the other forums as well and figured your were well on the way.

If it would be me, I'd check and monitor that voltage source. Since it goes high after some time being turned on and is not stable wandering around, I'd say it is heat related. It could be something stupid like a cold solder joint.

[No1baggiesfan]

Re: Another Yamaha

Apologies, I forgot about the service manual.



Not easy to look at on an iPhone lol.

I haven't spent a lot of time on it so far, mainly checking for dry joints, and checking caps that have been mentioned in previous posts.

[kndm17]

Re: Another Yamaha RXV671

Apologies, I forgot about the service manual.



Not easy to look at on an iPhone lol.

I haven't spent a lot of time on it so far, mainly checking for dry joints, and checking caps that have been mentioned in previous posts.

Hi, Please Do check all the Transistor Amplifier. each pair consists of PNP and NPN Transistor. Make sure that they are okay. try to compare the measurement. then after that try to hang all QPins one by one. after that go to Protection Circuit and check if there is no suspicious component.

If all the components are okay you can proceed to check the Main Power Supply.

Thanks.

[redrooster]

Re: Another Yamaha RXV671

Hi, Please Do check all the Transistor Amplifier. each pair consists of PNP and NPN Transistor. Make sure that they are okay. try to compare the measurement. then after that try to hang all QPins one by one. after that go to Protection Circuit and check if there is no suspicious component.

If all the components are okay you can proceed to check the Main Power Supply.

Thanks.

What do you mean by "Hang all Qpins one by one? I've been repairing gear for years if I don't know what you are talking about how is this guy going to figure it out?

[CapLeaker]

Re: Another Yamaha

Well, I'd start measuring all voltage rails and see what gives. There are 2 options. A: a regulator failed, or B: something is dragging a voltage rail down.

[redrooster]

Re: Another Yamaha

Have you checked for burnt or discolored resistors? Give the amplifier a good clean with a new paintbrush and vacuum cleaner, dirt and fluff can become moist and conductive causing the protection to cut in. If you don't know how to test transistors or whatever just say so.

[No1baggiesfan]

Re: Another Yamaha

From what I can see there are no burnt, discoloured or swollen components, the inside is tbh quite clean.
If I've read the manual correctly, then Ic89 is a required voltage test, but I can't see in the manual what they are supposed to be.
Video 7 board has 7.2v off both terminals
Video 2 board has 5.4v from all 4 pins to video 3 board
I'm getting 46v and 21v from transformer, but that is in circuit
None of the "transistor amplifier" test as shorted, all gave the same ohm reading

Qpins ?

[redrooster]

Re: Another Yamaha

From my experience with Yamaha amplifiers, nothing really goes wrong with them unless they are dirty or get overheated? Do an ohms test on your speakers at the terminals, what are they reading and do they match?

[R_J]

Re: Another Yamaha

Measuring the resistance across the speaker terminals will check open because the relay contacts will be open. If you want to check the resistance of the outputs, check between ground and the center of the dual 0.22Ω emitter resistors.
Do a diode check of the 4 diodes in D1040 bridge rectifier.

[redrooster]

Re: Another Yamaha

You have misread my post. I'm talking about measuring the speaker terminals! One of those might be causing the protection to cut in.

[R_J]

Re: Another Yamaha

It is unlikely a shorted speaker would cause this, the protection activates when it sees a high DC offset voltage on the outputs.
From the error that is given it is likely one of the low voltages that is at fault

[No1baggiesfan]

Re: Another Yamaha

It's definitely not a shorted speaker, there is nothing connected to the amp to cause a short and this amp has speaker short protection anyway, I know lol, I saw the 'check spkr' message a few years back when I first installed it

[R_J]

Re: Another Yamaha

A error P1-2 PS: 160/129 would indicate a fault with the lower voltages like 5v 3.3v etc.
Check your + & -12 volt supplies, also check the voltages on Q1067 collector and Q1068 emitter. If they are ok, the fault could be with one of the 5v or 3.3v voltages, there are more than one of each
Check that you have a good 5.5v coming from the ac-dc converter, this is the standby voltage that is allways on and is the source for the 3.3m voltage to the digital board

[CapLeaker]

Re: Another Yamaha

A error P1-2 PS: 160/129 would indicate a fault with the lower voltages like 5v 3.3v etc.
Check your + & -12 volt supplies, also check the voltages on Q1067 collector and Q1068 emitter. If they are ok, the fault could be with one of the 5v or 3.3v voltages, there are more than one of each
Check that you have a good 5.5v coming from the ac-dc converter, this is the standby voltage that is allways on and is the source for the 3.3m voltage to the digital board

That's what I am thinking too. The fault code indicates a low voltage rail problem.

[No1baggiesfan]

Re: Another Yamaha

12v on CB101 is 15.4v
Q1067 is 0.6v middle/top 0.05v middle/bottom
Q1068 is 1v Middle/top 1.6v Middle/bottom

[R_J]

Re: Another Yamaha

CB101 is the AC input to the D1041 bridge rectifier from the transformer, You would be better off checking the DC voltages on the regulator ic outputs, IC101 should have +12 volts, IC102 should have -12 volts.
learn what the pinouts are on transistors, Q1067/Q1068 need to be checked when the amp is turned on. If it is in standby you will not have any voltages at all.
There are about 20 different voltage sources in this amp, you need to be able to identify them and then check there voltages