yamaha RX-V365 Receiver

Maybe something got lost in the translation. DC output of the power amplifier will only show up at the speaker terminals if the speaker relay is energized. It's not clear to me what protection functons are being bypassed by pressing the "Effect" & "Night" buttons. In other words, check the DC at the power amp output before it goes to the protection relay. Other than that, perhaps our resident Yamaha expert, Mark Z. will chime in with some advice. (-:

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David Farber 
Los Osos, CA

The translation is a bit off. It's trying to say that there WAS a DC offset at one or more speaker terminals, therefore the protect was activated. The DC is actually detected BEFORE the speaker relays via sensing resistors going over to the appropriate DC PRT input on the microprocessor. The value 210 translates as follows:

divide 3.3 by 255. This equals 0.01294117

Multiply this value times the error code 210. The result (2.717647) is the voltage seen at that input on the microprocessor. Actually it's quite accurate - no need for a multimeter here.

The acceptable range (maybe 70 to 125 etc) multiplied the same constant would give the "normal" DC range that should be seen by the microprocessor.

Bottom line - probably one channel has a DC offset caused by a bad output IC.

That DC voltage can be measured at any of the white emitter resistors sitting in front of the output IC's. One white dual resistor for each channel.

In this case, since it is not an over-current shutdown, the protection cancel method shown in the manual can force the receiver to stay ON so that voltage readings can be made.

Enough?

Mark Z.

Thank you so much guys. Will post my findings soon. PS: I've been toggling the power on and off to get readings. Protection bypass didn't seem to matter, although unit will stay running in firmware update mode.

Regards: Bill

Measured the center post on ceramic resistors in front of amp i.c.'s (4) measured .8vdc (1) measured 52.6 vdc. (front-left speaker output) of STK433-330-E Replace the I.C. ? Any other offending parts I should look at?

I heard a high pitch sound the other day and thought it was around the volt age regulators on operation board 2. LOL (not even close) It was the STK43

3-330 I.C. . Oh well, the regulators got a new grease job and the 6.3v 1uf caps checked out good with ESR and LC meters.

Checked Q119 (2n5551c) with dvm. I checked ok.

Hi I have the same problem with my receiver, did you managed to fix it?

Thanks

I just ordered a (4) piece lot of the STK433-330. I'm quite sure it will be fine. I will have 3 extras if you want to purchase 1 from me. I'm not sure when they will arrive.

Did you check the voltage outputs of the amp of the (7) protection circuit resistors? They are the white large cement (ceramic) type.

Download the datasheet and it will demystify the the circuit and how it works. I found it quite interesting, especially the 8 bit code to the MCU stuff that Mark Z explained. I haven't delved much into that yet (just curious) The overvoltage protection circuit is neat how it puts the amps into standby mode, etc..

Update: Amp IC on back order. looking at other sources.

Hi did you have any joy with the IC's you ordered? Have you for any for sale?

What's it to you?

THis thread is from early 2013, now almost 2 years ago. You weren't posting when he was having a problems, so why should you care?

And if you really have to dig up old posts to reply nonsense to, at least have the decency to quote what you are replying to, so there is context. We aren't all at google, we don't see 2 year old messages on one single page.

For that matter, always check the date before replying.

Michael