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Post by masterdoor on Nov 14, 2015 7:59:43 GMT -5
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Post by jeremy on Nov 14, 2015 13:07:23 GMT -5
The receiver is likely not "Dead" as you put it. It is most likely in a protection mode which will give the appearance of a totally dead unit. Yamaha is famous for that feature... Theres a certain button sequence you need to do on the front panel to clear the protection mode and get the receiver to power on. I don't know what it is off hand for your model. In regards to that, it likely went into protection because of a power surge or possibly a shorted component in the amplifier. Mastertech should be able to help you get it fired back up though  |
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Post by masterdoor on Nov 14, 2015 16:17:44 GMT -5
I've tried with no luck "Press and hold the "tone control and info" buttons. While holding, press and release the "main zone" button while keep holding the other 2 buttons for another 5 seconds"
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Post by mastertech on Nov 14, 2015 20:22:39 GMT -5
How about IC98 3.3s?
Also check pins 170 and 171 of MPU ic81 for voltage.
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Post by masterdoor on Nov 15, 2015 7:01:48 GMT -5
Missed that one  Checked: IC98 3.3V MPU IC81: 3.3V on pin 25,69,115,164,170,171,174,175 |
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Post by mastertech on Nov 15, 2015 10:02:44 GMT -5
What happens to the voltage on pins 170 and 171 when you push the power button?
Also check the same on pin 27, voltage with power pressed and released.
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Post by jeremy on Nov 15, 2015 12:13:39 GMT -5
I've tried with no luck "Press and hold the "tone control and info" buttons. While holding, press and release the "main zone" button while keep holding the other 2 buttons for another 5 seconds" Yes thats the reset thats published in the user manual. Some of these Yamaha's have a more in depth reset thats only explained in the service manual. So there's still the possibility its just protecting itself, unless mastertech knows something I don't (which is very possible too!) |
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Post by masterdoor on Nov 16, 2015 11:21:43 GMT -5
I appreciate all the help. Pin170 3.3V. Powerbutton pushed 3.3V Pin171 3.3V. Powerbutton pushed 2.46V Pin27 0V. Powerbutton pushed 3.3V jeremyService manual says this to disable protection mode:  |
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Post by mastertech on Nov 17, 2015 10:42:56 GMT -5
Go to pin 171 again and this time push the tone control button and see what the voltage drops to.
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Post by masterdoor on Nov 17, 2015 11:29:17 GMT -5
Tone control 2.71V
Zone2 1.38V
Zone control 1.10V
Radio 0V
CD 0.30V
Tv 0.55V
BD/DVD 0.85V
The other ones - no changes 3.3V
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Post by mastertech on Nov 17, 2015 17:50:46 GMT -5
Almost done. Test voltage on pins 4,15,165 both before pressing power button then after.
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Post by masterdoor on Nov 18, 2015 13:35:06 GMT -5
No change when pressing power button.
Pin4 0.5V
Pin15 0V
Pin165 3.3V
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Post by mastertech on Nov 19, 2015 0:37:18 GMT -5
Well everything does look to be correct so that would leave a problem with the cpu not working properly. But it would not mean the cpu is the conclusive failure. The eeprom, crystal or even a short on a control line can cause the cpu to lock up. The cpu does not appear to be shorted like some others that have been found in yamahas.
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Post by masterdoor on Nov 21, 2015 19:37:28 GMT -5
Thanks for the guidence this far.
The crystal have a nice 8Mhz sinewave.
What is a control line? Where does it go between?
If the eeprom lock up the cpu and i desolder it, could i then see something happen in display?
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Post by masterdoor on Nov 27, 2015 10:30:12 GMT -5
I desoldered the eeprom, but still dead. Thought if eeprom would lock up MPU it should say that it couldn't read eeprom now. Guess the problem lays in MPU. Can i change MPU, or does it need preinstalled firmware? Control line, is that the communication between MPU and eeprom?  |
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