Yamaha RX-V*7* series protection circuits

[videobruce]

Yamaha RX-V series (specifically the 675) won't power up.
This isn't a bad caps problem, but appears to be their overly aggressive protection circuit problem.

I got it uses, initially it did power up. Going through testing all the inputs and outputs (except for the surround speaker outputs) all was fine.
After a few hours, I came back to familiarize myself with the on screen menu, but it didn't respond to the front panel button. I unplugged and re-plugged it and it did power up.
The next day no power At all, removing the power cord and re-applying it made no difference. I did hear the relay(s) click a couple of times, but tht was it.

I checked the standby board fuse which was good. I did check the input lead to the main xformer and it was not open (in case it had a thermal fuse). I tried the 'Info-Tone Control-Main Zone' button trio protection bypass per the SM, but still nothing.

The volume was at mute (turned all the way down). I only had a pair of bookshelf speakers connected to the front outs (and no, the cables were not shorted). I only ran at low levels just to confirm audio output.

Nothing obvious inside other than a 'musty' smell like one smells from 30 year old equipment. This is only three years old or less and it was 'refurbished' which means someone else had a problem, not doubt this.

Any ideas with their protection circuit assuming that is the probelm area?

[Longbow]

Re: Yamaha RX-V*7* series protection circuits

I checked the standby board fuse which was good.

But what about your standby 5v?

I did check the input lead to the main xformer and it was not open (in case it had a thermal fuse).

But what about your secondary voltages on the supply?

I tried the 'Info-Tone Control-Main Zone' button trio protection bypass per the SM, but still nothing.

That would be getting ahead of yourself, since you don't have a stable turn-on.

[honda191]

Re: Yamaha RX-V*7* series protection circuits

I have exactly the same amp and issue! Read somewhere about a Thermal Fuse in the power supply but the model in the U tube video I reviewed is different they have a grey and blue wires my amp has a blue and white wire that comes from the input board to the power supply to a small board on the power supply. My question is how to bypass the original thermal fuse and install the new replacement???

[budm]

Re: Yamaha RX-V*7* series protection circuits

The question is, is the Thermal fuse open circuit? It is wrapped under the insulation tape on the Primary winding of the transformer. So did you check resistance of the primary winding of that main power transformer?
Did you verify that you do have MAIN AC between the White and Blue wires soldered to the PCB on the transformer?

[honda191]

Re: Yamaha RX-V*7* series protection circuits

I did not check power I will tonight but I did check resistance and there was none between the white and blue wire at the board.

[budm]

Re: Yamaha RX-V*7* series protection circuits

If it shows open circuit then you do have open primary circuit, so the thermal fuse may have blown open circuit dues to fault in the transformer. You need to remove the transformer to the fuse under the wrapping.

[honda191]

Re: Yamaha RX-V*7* series protection circuits

The small board that had the blue and white wires connected to the power supply had a bad trace. Removed the board wired directly to the leads to the supply and now I can get the amp to power up in sleep mode. I disconnected all speaker wires and tried to power up normally but shuts down.

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Here is a picture of input connections on the Power Supply hoping you can see the 2 small silver wires connecting to the main is solder junction is this the connection of the Thermal Fuse?? I checked resistance and it is open. I need a little help on where to cut and re solder in the new one.

[budm]

Re: Yamaha RX-V*7* series protection circuits

Can I see the whole transformer top side?
They usually have the thermal fuse on the primary, your pictures look like the secondary side?
But I though you fixed the connection on the primary side and able to get the resistance reading on the primary winding.
BTW, what is the full model number?

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Model RXV765 I did run the protection diagnostics actually 3 times each time resetting the code it reads dc016L

[budm]

Re: Yamaha RX-V*7* series protection circuits

Do you have the service manual?

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Yes all printed out

[budm]

Re: Yamaha RX-V*7* series protection circuits

So what does it say in the service manual for the error code dc016L?

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Dc current low

[honda191]

Re: Yamaha RX-V*7* series protection circuits

016 = A/D value when the protection function is activated reference voltage 3.3 v

L= when the lower limit of the protection function is exceeded.

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Any help on where to look for the source of issue with the DC over voltage???

[budm]

Re: Yamaha RX-V*7* series protection circuits

I looked at the service manual that I sow on the link, where do you see the error codes listing?

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Page 62 is where I got the above description.

BTW, I had the amp in sleep protection mode last night and got distracted for an hour or so came back to my bench and it was totally powered off and now I can not get any response other than the initial click no there relays function display does not light up. Tested Ac in to power supply (Blue and white Wires) and no voltage. Should I just order a new main board if so how do you go about ordering it from Yamaha?

[honda191]

Re: Yamaha RX-V*7* series protection circuits

Page 108 in the manual is the board for power in can't seem to find the part number for the whole board assembly? I think it is WR433800 but not 100% sure

[madan1]

Re: Yamaha RX-V*7* series protection circuits

can you post some images of the unit and the individual PCBs?
the dc power regulators usually look like transistors and are mounted on radiators or the chasis. They have 3 legs ( input ground output , order differs ). Near them you will find e-caps. On the pcb it should be undicated for whuch dc line is the regulator ( +/- 12, 8, 7, 5, etc V ).