Its definitely a laborious job.Not one of my favorites anyway.But it needs to be done.Those switch contacts are silver plate. Tarnish,dust and moisture make them look pretty bad.
Yamaha CR-840 Repair
- Thread starter mrjoemorgan
- Start date
Thats not good....................
mrjoemorgan
Member
Okay update. I unplugged one speaker and left one in. BINGO, music is back, working perfectly.
However, i turn it off and plug in the 2nd speaker. I turn it on and the "click" is back. However, there is no sound anymore. I can hear feedback in the speakers when I play around with the A/B speaker switch but nothing comes out.
Turn it off, unplug the 2nd speaker to go back to just 1 and same thing, no sound
mrjoemorgan
Member
BINGO!!! The magic ogfDe-Oxit is real! After taking random things apart and putting them back again and using some de-oxit and high-pressure air pressure spray, its WORKING!
Thank you so much Dave for your help.
One question that remains. Mode. Mono v Stereo. What is that exactly? At the moment it just changes the sound a little, one makes the highs a little more muffled.
Mono combines L & R and both amplifiers output the same audio. STEREO there is a defined L channel and R channel. Leave it in Stereo position.
mrjoemorgan
Member
That makes sense. So things are not 100% yet.... I plugged in my record player. It's an Audio Technica so its new record player. There is a lot of feedback from the speakers - if I wiggle the phono cables in the back of the receiver the feedback is more noticeable. About 2/3 songs in the sound cut out again. I turned it off, left it a moment, turned it back on and the sound came back.
So maybe its an issue with the PHONO input that causing something to trip?
cnolanh
Ad astra
Glad you got the Yamaha working! You certainly want the mode set to Stereo for most listening. For the phono trouble, it's possible that you need to clean dirt/corrosion from the RCA jacks on the back of the receiver. Also the Input Selector switch might need more (careful) DeoxIT treatment. It's possible that the Phono position has more dirt/corrosion in it than one of the other positions.
There are multiple other controls that may well need more cleaning later on, since they can cause sound dropouts when dirty (Volume, Balance, Loudness, Speaker switch, etc.). I've done a couple rounds of DeoxIT on my CR-840 and it's pretty smooth now.
And interestingly, the Low Filter switch on my CR-840 has also failed (despite the fact that it's almost never been used).
There are multiple other controls that may well need more cleaning later on, since they can cause sound dropouts when dirty (Volume, Balance, Loudness, Speaker switch, etc.). I've done a couple rounds of DeoxIT on my CR-840 and it's pretty smooth now.
And interestingly, the Low Filter switch on my CR-840 has also failed (despite the fact that it's almost never been used).
mrjoemorgan
Member
Good to know, thank you. Ill give it another going over tomorrow.
So the only thing I notice in the Stereo vs Mono is more bass vs more treble.
That switch may need some more deoxit as well. You should be able to distinguish a 2-channel sound stage versus a 1-channel sound stage.
mrjoemorgan
Member
I spoke too soon. Used it last night for a few hours and it was perfect. No issues at all. Even using my record player for the most part.
This morning I put on a record. The only thing I changed was I realized that I had it on mono, not stereo. So I changed it to stereo. 1.5 songs later, the speaker let out a loud crack and the sound was gone.
I no longer got the "click" when I turn it on and off. I left it for 10 minutes, turned it back on and the crack was back and the sound working again.
I am not sure if it was the Mono/Stereo that did it. I have put it back to Mono to see if it happens again. Do you think thats the issue? Mono vs Stereo?
One question - my bedroom is quite cold and a little damp (old victorian house in San Francisco where its been raining a lot) - does that play in at all?
UPDATE - about 5 minutes after posting this. I heard a crack in the left speaker and the whole thing died again. This time with the Mono switch on.
Could it be the speakers that are causing the issues?
mrjoemorgan
Member
UPDATE: After about an hour, the unit gave me the "click" again. The sound is back, but nothing in the LEFT channel A or B.
The speaker which WAS in the left channel as given me trouble in the past. I had to replace the woofer in it. (Boston Acoustic CR9s) - so i wonder if its a bad speaker causing the receiver to trip?
I have both speakers in the RIGHT channel now (one in A and one in B) and they are both working fine.
Update - 5 minutes after posting this it tripped again. All sound gone
The speaker which WAS in the left channel as given me trouble in the past. I had to replace the woofer in it. (Boston Acoustic CR9s) - so i wonder if its a bad speaker causing the receiver to trip?
I have both speakers in the RIGHT channel now (one in A and one in B) and they are both working fine.
Update - 5 minutes after posting this it tripped again. All sound gone
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mrjoemorgan
Member
I wasn't able to check - i left it for 4 hours and the "click" hasn't come back. Maybe worth replacing the STKs? It seems to be tripping the protection relay. So with the L channel being funky, im sure the pressure on the R channel made the protection relay trip?
mrjoemorgan
Member
Bought a couple of STKs online. Replaced them in the 840 but whilst the unit turns on, still not getting the click. Anything else I should try?
Need to determine if you have any DC voltage on the output pins of both of the STK's.