Had to desolder this part and re-break it were I glued it together. Sure enough some excess glues was in there. Now the switches stick again. I'll be more careful with the glue this time. At this point i guess I'm documenting this in case someone else comes along with these issues - slef inflicted or not!
Yamaha C-80 lost sound switching inputs
- Thread starter ghankstef
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- preamp yamaha c-80
Had to desolder this part and re-break it were I glued it together. Sure enough some excess glues was in there. Now the switches stick again. I'll be more careful with the glue this time . Guess I am documenting this now in case someone else needs to do this.
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It's good to show our mistakes IMO. I was thinking 2 things:
1. There's alot of parts donor C-80's out there from smashed volume controls. Maybe the C-85, 65, 60 input selector boards would work too?
2. I'm wondering if acetone would break up the super glue but it might cause other problems in the process...like eating the switch,lol
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Good ideas - I'll try the acetone and start looking for a donor unit.
Still a lot of work to do on this preamp.
Only two inputs working (DAD and tuner), has a general hum and the phono stage has a terrible hum. Going to check my solder joints on the input board and the joints of the RCA inputs.
Then touching the variable loudness pot increases the hum.
Phono stage still has a very loud hum - louder than the other inputs. Reflowing the phono ground solder joint and tightening the screws on the board didn't help. I even tightened the screws for the transformer. Tightened them as much as I could without risking them getting too tighten and unable to loosen again.
The hum is interesting in that if I have a source connected to say the DAD input the hum is less. If I turn the volume all the way up or all the way down, the hum seems to go away but in between the hum is there. Maybe I need to reflow solder joints on the volume/loudness board too.
Only two inputs working (DAD and tuner), has a general hum and the phono stage has a terrible hum. Going to check my solder joints on the input board and the joints of the RCA inputs.
Then touching the variable loudness pot increases the hum.
Phono stage still has a very loud hum - louder than the other inputs. Reflowing the phono ground solder joint and tightening the screws on the board didn't help. I even tightened the screws for the transformer. Tightened them as much as I could without risking them getting too tighten and unable to loosen again.
The hum is interesting in that if I have a source connected to say the DAD input the hum is less. If I turn the volume all the way up or all the way down, the hum seems to go away but in between the hum is there. Maybe I need to reflow solder joints on the volume/loudness board too.
Make sure the volume/loudness controls mounting hex nut is securely tightened. -- grounded to the chassis.
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in terms of donors checking on fleabay I got this one for $100 and even parts and repair units seems to be going for $3-400!
I checked barter town for ya...nothing at this time. Since it's the Tape 2 input that's broke I'd say F it, who uses that? As long as Tape 2 isn't stuck engaged, all the other inputs should toggle. All the other inputs work?
Esoteric Redneckisms
Are ya using headphones for sound checks? It's been a few years since I fixed my C-80 but I remember it hummed alot with headphone testing. Hum went full weird when I touched the volume. It worked well for me when I fed it to an amp though.
Can't remember if it was a chassis ground issue (lug on the back) or was from the face cover being off. Good luck.
No only DAD and Tuner inputs work. Phono maybe "works" but has a terrible hum. Aux and Tape 1 - no sound aside from the general hum a hear - probably a 60hz hum I haven't figured out the cause of. Do you think I need to short out the tape 2 section on the input selection board somehow?
Ah! I get a similar thing. It has a general 50 or 60hz hum (guessing but it sounds like the electrical hum you hear). I am testing it with a Fosi Audio V3 class D amp and some minimus 7 speakers. It sounds gorgeous apart from the hum but if I test anything metal - the case, the loudness pot, another pot - the hum gets worse. Here is a 12 second video to demonstrate:
Dropbox
www.dropbox.com
The hum is less bad with a source connected but still there.
Spent time tonight reflowing solder joints for the rca inputs and on the input selector board. I also tightend the hex nut on the volume/loudness pot. Still have these issues:
1. general 50 or 60hz hum that is less bad with a source connected but louder when selecting an input without a source attached and even worse with the phono input selected
2. Only DAD and Tuner inputs work - or maybe phono does but it has such a horrible hum I haven't tried it yet.
Do you think since Tape 2 is missing the component the switch uses - that is causing the 2 other inputs on the same row - aux and tape 1 not to work? Do I need to short out tape 2 somehow? See photo attached.
Also some pins don't even have a solder pad or solder underneath (2nd and 3rd photo) should I do something about that - bridge the pin/leg to another component in the same path on the board or scrape off to the copper in that spot and solder from the leg to there with a piece of wire?
Appreciate all the tips here. Really hoping to get this thing working better as it sound fantastic in spite of the hum.
1. general 50 or 60hz hum that is less bad with a source connected but louder when selecting an input without a source attached and even worse with the phono input selected
2. Only DAD and Tuner inputs work - or maybe phono does but it has such a horrible hum I haven't tried it yet.
Do you think since Tape 2 is missing the component the switch uses - that is causing the 2 other inputs on the same row - aux and tape 1 not to work? Do I need to short out tape 2 somehow? See photo attached.
Also some pins don't even have a solder pad or solder underneath (2nd and 3rd photo) should I do something about that - bridge the pin/leg to another component in the same path on the board or scrape off to the copper in that spot and solder from the leg to there with a piece of wire?
Appreciate all the tips here. Really hoping to get this thing working better as it sound fantastic in spite of the hum.
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Sounds to me like the tactile switch is mechanically hosed up. My 80 wasn't as challenging as yours so I'll take a step back. Mine just needed the glue service, some solder reflowed, switches & pot cleaning, and a boring re-cap...86 of them, lol.
EDIT: 62 caps vice 86, still boring though, lol
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Sometimes a guy buys a Fbay piece that truly means donor. I bought 3 pieces that must have been dumpster rescues, hoping I could fix them. One of them was in a house fire.
Yeah mine was humming like that too. Just like in your video. I do remember it stopped after I removed the cheap CD player I was using as a source. Sounded fine with a tuner.Ah! I get a similar thing. It has a general 50 or 60hz hum (guessing but it sounds like the electrical hum you hear). I am testing it with a Fosi Audio V3 class D amp and some minimus 7 speakers. It sounds gorgeous apart from the hum but if I test anything metal - the case, the loudness pot, another pot - the hum gets worse. Here is a 12 second video to demonstrate:
Dropbox
The hum is less bad with a source connected but still there.
EDIT: Best I can explain is...that thing is sensitive to ungrounded signals. My finger is an ungrounded signal. So yes, when I touched the front chassis, volume knob, I heard that 60Hz hum too. Try a different input source like a tuner. Put the face cover on with a screw or two. Better yet,put the bottom cover service panel back on at the metallic screw spots, especially the ones in the center riding the aluminum chassis rail, I'll bet that hum goes away.
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If your from MN. It would be 60hz or 120hz.
Because those pins are not used. So don't go jumper connecting them to anything.
No visible leakage or anything. I can pull them and test them with a multimeter if need be. Oh and I have a cheap component tester that gives me ESR readings might be worth a shot.