Yamaha RX-797 problem...opinions?

bmwscoot · 12th June 2009, 04:50 AM

Hi guys,
New guy here.
I have a problem with a 2.5 year old Yamaha RX-797 Receiver.

All of a sudden, it will not produce any sound unless the "pure direct" button is enabled.
Essentially, this bypasses all tonal control, balance control, etc.
With the "pure direct" enabled the amplifiers work wonderfully, but with no control of tone/balance of course.
I would guess this indicates a problem in either the tone control sub-board, or the "pure direct" sub-board?
Mother Yamaha cannot even recommend a repair facility, or even let me know if there are any T.S.B.'s on this problem.
A Google search yielded a few other people with this same condition in their RX-797, but so far no one has posted any replies on if this is a known problem, etc.
Anyone?
Thanks in advance...

sakis · 12th June 2009, 04:21 PM

to check for dirty switches

proper spray to clean them is not an easy choise ..... apply lilte work them as much is possible ...

WD40 spray is a bad choise ..... red caned spray of philips is an option and there is more better

jaycee · 12th June 2009, 05:51 PM

With a schematic, the best thing to do would be to try and sniff the signal as it goes through. A pair of cheap headphones would do, wire the ground to signal ground, and take the tip of the plug to a probe you can position on the circut. Play a sine wave or something into it and see where it disappears.

A scope would be better for that of course

Of course, I'm also assuming your skills are up to this kind of work. You would have to have the case open and the amplifier powered, so there's a risk.

If you're looking for something quick to try, see if you can find a replacement for the Pure Direct switch and simply try replacing it. You could remove the switch and use wire to hardwire it in the "on" position if you wanted.

PM650 · 13th June 2009, 06:43 AM

The problem is either something on the tone control board, the pure direct switch itself, or the connectors/wire to the tone control board. Send me an email and I will respond with the 797 service manual.

unclejed613 · 13th June 2009, 03:13 PM

pure direct bypasses the DSP board. you either have a bad DSP board or are missing one of the power supplies that feed it. pure direct is one of the troubleshooting steps for determiming whether the problem is with the DSP board or elsewhere, at least on yamahas. other manufacturers have other ways of bypassing the DSP for testing.

bmwscoot · 13th June 2009, 03:28 PM

PM650.
As I am a new member here, I am not yet allowed to email current members.
Please if you have time, email ME!

I had the audio board and switch board out to check for switch operation, and cold solder joints, etc....everything looks fine. I figured out the operation of the switch, and it mimics the other identical "direct CD" switch next to it.
But, w/o a manual or schematic I am looking for the "needle in a haystack".
If you have time, please email me.
Or any other members here that see this please email PM650 to tell him I cannot as yet contact him.
Thank You!

PM650 · 14th June 2009, 06:07 AM

I cannot send you an email until you enable it in your profile options.

unclejed: This is a simple stereo receiver; it has no audio processing (other than electronic input switching). Even the pure direct switch is a physical 6PDT switch

unclejed613 · 14th June 2009, 05:21 PM

sorry... guess i've got so used to seeing DSP in just about EVERYTHING that i got DSP crazy......

bmwscoot · 14th June 2009, 10:12 PM

PM650...

OK, emails good to go.
I'm still too new here for me to get your email, though.

Thanks!

12th June 2009, 04:50 AM	#1
bmwscoot diyAudio Member Join Date: Jun 2009	Yamaha RX-797 problem...opinions? Hi guys, New guy here. I have a problem with a 2.5 year old Yamaha RX-797 Receiver. All of a sudden, it will not produce any sound unless the "pure direct" button is enabled. Essentially, this bypasses all tonal control, balance control, etc. With the "pure direct" enabled the amplifiers work wonderfully, but with no control of tone/balance of course. I would guess this indicates a problem in either the tone control sub-board, or the "pure direct" sub-board? Mother Yamaha cannot even recommend a repair facility, or even let me know if there are any T.S.B.'s on this problem. A Google search yielded a few other people with this same condition in their RX-797, but so far no one has posted any replies on if this is a known problem, etc. Anyone? Thanks in advance...

12th June 2009, 04:21 PM	#2
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	youmay need to check for dirty switches proper spray to clean them is not an easy choise ..... apply lilte work them as much is possible ... WD40 spray is a bad choise ..... red caned spray of philips is an option and there is more better __________________ SERVICE ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

13th June 2009, 03:13 PM	#5
unclejed613 diyAudio Member Join Date: Dec 2006	pure direct bypasses the DSP board. you either have a bad DSP board or are missing one of the power supplies that feed it. pure direct is one of the troubleshooting steps for determiming whether the problem is with the DSP board or elsewhere, at least on yamahas. other manufacturers have other ways of bypassing the DSP for testing. __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

14th June 2009, 05:21 PM	#8
unclejed613 diyAudio Member Join Date: Dec 2006	sorry... guess i've got so used to seeing DSP in just about EVERYTHING that i got DSP crazy...... __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

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12th June 2009, 05:51 PM	#3
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	With a schematic, the best thing to do would be to try and sniff the signal as it goes through. A pair of cheap headphones would do, wire the ground to signal ground, and take the tip of the plug to a probe you can position on the circut. Play a sine wave or something into it and see where it disappears. A scope would be better for that of course Of course, I'm also assuming your skills are up to this kind of work. You would have to have the case open and the amplifier powered, so there's a risk. If you're looking for something quick to try, see if you can find a replacement for the Pure Direct switch and simply try replacing it. You could remove the switch and use wire to hardwire it in the "on" position if you wanted.

13th June 2009, 06:43 AM	#4
PM650 diyAudio Member Join Date: Jul 2005 Location: Tennessee	The problem is either something on the tone control board, the pure direct switch itself, or the connectors/wire to the tone control board. Send me an email and I will respond with the 797 service manual.

13th June 2009, 03:28 PM	#6
bmwscoot diyAudio Member Join Date: Jun 2009	PM650. As I am a new member here, I am not yet allowed to email current members. Please if you have time, email ME! I had the audio board and switch board out to check for switch operation, and cold solder joints, etc....everything looks fine. I figured out the operation of the switch, and it mimics the other identical "direct CD" switch next to it. But, w/o a manual or schematic I am looking for the "needle in a haystack". If you have time, please email me. Or any other members here that see this please email PM650 to tell him I cannot as yet contact him. Thank You!

14th June 2009, 06:07 AM	#7
PM650 diyAudio Member Join Date: Jul 2005 Location: Tennessee	I cannot send you an email until you enable it in your profile options. unclejed: This is a simple stereo receiver; it has no audio processing (other than electronic input switching). Even the pure direct switch is a physical 6PDT switch

14th June 2009, 10:12 PM	#9
bmwscoot diyAudio Member Join Date: Jun 2009	PM650... OK, emails good to go. I'm still too new here for me to get your email, though. Thanks!

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