Rotel RX-950-AX

shocks · 11:47 PM

Hello and Happy Thanksgiving
My Partners Rotel won't power on

My business partner and I have been giving each other birthday gifts for 30 years. Needless to say I was running low on ideas. I asked him if he had any wishes and he asked me if I could take a look at his Rotel Rx-950-AX receiver because it had a broken "power on button". To make a long story short after searching the net for two weeks I finally found a DPDT switch that would fit the circuit board and I installed it for him. (it had lost its latching ability). Voila replaceing the switch is was not the problem. It remains in standy.
So far I removed two capacitors located near the transformer c955 and V956.
I have not replaced them yet. I have identified the diode recitifier and some other capacitors of interest 902,903, 905,907. I tested the 902 and 903 with an ESR meter and I believe those caps are good. I can not test 905 or 7 without doing a tremendous about of work removing the board. I was wondering if anyone could give me some testing ideas that might help me isolate the problem better. I hve not tested the diode recitifier yet.
Thank you
I can provide pictures if needed.
Also tried to upload service manual from another site but "size to big"

Thanks Bill

bullittstang · 30th November 2020, 12:05 AM

Have you checked to make sure you have proper supply voltages? If not do that first, because it will more than likely tell you they are fine and it is protection not stand-by issue.

If it is protection, most likely you have DC on the speaker outputs and have a shorted output transistor and maybe a driver transistor.

First is to verify you have all voltages you should, then move to the harder stuff to find the issue.

shocks · 30th November 2020, 12:32 AM

Thank you for those quick and thoughtful ideas bullitstang. Could you step me through that if I could get the service manual to you. I have all the equiptment but my know how is lacking.

bullittstang · 30th November 2020, 12:45 AM

I would post the manual and schematic on the forum.

I can certainly help but there are others that will jump in that are way more knowledgeable than me. It also will assist those that might have the same issue in the future.

shocks · 01:09 AM

Thank you.
I reduced the PDF so I can upload
I am pretty good at locating things and have a rudimentary understanding of diagrams but this unit looks complicated to me.

shocks · 30th November 2020, 01:10 AM

Sorry the attachement got a bit blurry when I reduced size

bullittstang · 30th November 2020, 01:13 AM

Maybe start with uploading the power supply, any schematic diagrams and amp board as separate individual PDFs.
As it is it’s of very little use.

shocks · 30th November 2020, 01:24 AM

I apologize. I am off to a bad start with the schematic upload. I am using a Mac and I cant figure out how to upload a legible diagram. I could give teh other website where I download it from but I dont want to violate site rules.
Tomorrow I will have access to a pc and an adobe program and I can do a better uploading job. thank you and speak soon
Bill

PRR · 30th November 2020, 03:44 AM

Quote:

Originally Posted by shocks

...I could give teh other website where I download ...

It is in HiFi Engine, and we often post those links.

Rotel RX-950 AM/FM Stereo Receiver Manual | HiFi Engine

shocks · 30th November 2020, 01:45 PM

Thank you for posting the HiFi Engine service manual for me.
I guess my basic question is where do I place my meters electrodes to see if the power supply is putting out correct voltage?

29th November 2020, 11:29 PM	#1
shocks diyAudio Member Join Date: Dec 2015	Rotel RX-950-AX wont power on. In standby only Hello and Happy Thanksgiving My Partners Rotel won't power on My business partner and I have been giving each other birthday gifts for 30 years. Needless to say I was running low on ideas. I asked him if he had any wishes and he asked me if I could take a look at his Rotel Rx-950-AX receiver because it had a broken "power on button". To make a long story short after searching the net for two weeks I finally found a DPDT switch that would fit the circuit board and I installed it for him. (it had lost its latching ability). Voila replaceing the switch is was not the problem. It remains in standy. So far I removed two capacitors located near the transformer c955 and V956. I have not replaced them yet. I have identified the diode recitifier and some other capacitors of interest 902,903, 905,907. I tested the 902 and 903 with an ESR meter and I believe those caps are good. I can not test 905 or 7 without doing a tremendous about of work removing the board. I was wondering if anyone could give me some testing ideas that might help me isolate the problem better. I hve not tested the diode recitifier yet. Thank you I can provide pictures if needed. Also tried to upload service manual from another site but "size to big" Thanks Bill Last edited by shocks; 29th November 2020 at 11:47 PM. Reason: more thoughts

30th November 2020, 01:24 AM	#8
shocks diyAudio Member Join Date: Dec 2015	Rotel RX-950-AX wont power on. In standby only I apologize. I am off to a bad start with the schematic upload. I am using a Mac and I cant figure out how to upload a legible diagram. I could give teh other website where I download it from but I dont want to violate site rules. Tomorrow I will have access to a pc and an adobe program and I can do a better uploading job. thank you and speak soon Bill

30th November 2020, 01:45 PM	#10
shocks diyAudio Member Join Date: Dec 2015	Rotel RX-950-AX wont power on. In standby only Thank you for posting the HiFi Engine service manual for me. I guess my basic question is where do I place my meters electrodes to see if the power supply is putting out correct voltage?

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30th November 2020, 12:05 AM	#2
bullittstang diyAudio Member Join Date: May 2013 Location: Detroit, MI	Have you checked to make sure you have proper supply voltages? If not do that first, because it will more than likely tell you they are fine and it is protection not stand-by issue. If it is protection, most likely you have DC on the speaker outputs and have a shorted output transistor and maybe a driver transistor. First is to verify you have all voltages you should, then move to the harder stuff to find the issue.

30th November 2020, 12:32 AM	#3
shocks diyAudio Member Join Date: Dec 2015	Thank you for those quick and thoughtful ideas bullitstang. Could you step me through that if I could get the service manual to you. I have all the equiptment but my know how is lacking.

30th November 2020, 12:45 AM	#4
bullittstang diyAudio Member Join Date: May 2013 Location: Detroit, MI	I would post the manual and schematic on the forum. I can certainly help but there are others that will jump in that are way more knowledgeable than me. It also will assist those that might have the same issue in the future.

30th November 2020, 01:10 AM	#6
shocks diyAudio Member Join Date: Dec 2015	Sorry the attachement got a bit blurry when I reduced size

30th November 2020, 01:13 AM	#7
bullittstang diyAudio Member Join Date: May 2013 Location: Detroit, MI	Maybe start with uploading the power supply, any schematic diagrams and amp board as separate individual PDFs. As it is it’s of very little use.