solderdude
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Post by solderdude on Oct 25, 2020 19:40:11 GMT
I have not noticed a marker would be conductive. Maybe marker dependent. When it is fully dry there probably aren't conductive materials in there. Alternative: black paint (hobby paint, small pots for model airplanes) or black nailpolish (will probably exist) Nor does it matter because the 2 damaged pads are the same ground as what surrounds it. For solderrot you need high temp, and movement (for instance a heatsink expanding at higher temp) The currents are mA's Actually the marker/paint is more for covering the exposed copper track elsewhere. I'll look for those (at least a different brand of marker) once I am done with the volpot replacement
Thanks about the solderrot info by the way, it is my first time hearing about this. Does this happen to leaded solder more than non-leaded (RoHS) solder?
Solderrot is a weird name. Nothing is rotting though. It also isn't aging. They just call it solderrot. It is more a 'crack' caused by small movements. Looks like this, sometimes it isn't this clear but just a tiny small 'ring'.  In most cases a lot of current and mechanical stress is needed. The amp doesn't have high currents but some materials do expand. |
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Post by darkarn on Nov 13, 2020 6:23:17 GMT
Actually the marker/paint is more for covering the exposed copper track elsewhere. I'll look for those (at least a different brand of marker) once I am done with the volpot replacement
Thanks about the solderrot info by the way, it is my first time hearing about this. Does this happen to leaded solder more than non-leaded (RoHS) solder?
Solderrot is a weird name. Nothing is rotting though. It also isn't aging. They just call it solderrot. It is more a 'crack' caused by small movements. Looks like this, sometimes it isn't this clear but just a tiny small 'ring'. In most cases a lot of current and mechanical stress is needed. The amp doesn't have high currents but some materials do expand.
Ah, sorry, this took a while. Now I can see why you told me to focus on the tube socket given that its solder joints are large and there is mechanical stress on them. Thankfully the joints look fine
Meanwhile, Jeremy has sent out the volpots about a few days ago and I am looking to ship eyelets (and other tools maybe) via Amazon so it will be at least a month or two before I can update further about the volpot repair
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Post by darkarn on Nov 13, 2020 6:26:41 GMT
And meanwhile, I am looking to get something from Schiit and found these 6BZ7 and 6SN7 tubes too (https://www.schiit.com/products/tubes)
I am thinking of getting these tubes along with that something just to maximise the delivery charges  Will these be ok with Project Ember and the other Project amps? |
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solderdude
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Post by solderdude on Nov 13, 2020 16:49:05 GMT
The 6SN7 works well with Ember but you need a converter.
The 6BZ7 should work.
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Post by darkarn on Nov 15, 2020 10:11:33 GMT
The 6SN7 works well with Ember but you need a converter. The 6BZ7 should work.
Thanks, thankfully I have the 6SN7 converter ready for this
Meanwhile, is there any way to tell the bias voltage when using the Ember? I just want to see how much the tubes have degraded over the years. Or actually, is this an accurate way of doing so?
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solderdude
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Post by solderdude on Nov 15, 2020 11:00:56 GMT
The bias is constantly adjusted from the moment it is switched on. The process is slow enough to not affect the sound (think DC-servo).
At some point in time it will run out of adjustment range.
Telltale signs will be distortions at higher listening levels or noise creeping up.
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Post by darkarn on Nov 18, 2020 8:00:27 GMT
The bias is constantly adjusted from the moment it is switched on. The process is slow enough to not affect the sound (think DC-servo). At some point in time it will run out of adjustment range. Telltale signs will be distortions at higher listening levels or noise creeping up.
Thanks, I don't exactly listen at high levels though, so is trying to find noise the best way to find out?
Also, are there audio samples of failing tubes for me to listen to?
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Post by darkarn on Nov 18, 2020 8:02:34 GMT
The volpots are with me now by the way. I have removed the old volpot and placed the new one using jumper cables (i.e. not soldered onto the PCB) just as a quick way to test the volpot. Will comment more on this once I test it out properly and also when I get the pictures of doing the repair out of my camera
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solderdude
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Post by solderdude on Nov 18, 2020 12:08:02 GMT
crappy tubes can have channel imbalance, some become more microphonic (tapping them is audible), some become more noisy, others may start sounding poorly, others may have 'flickering noise'.
In the end tubes all fail.
That said, I have my fathers old tube radio in my work room and sometimes switch it on. The darn thing is 60 years old and the only thing that needs servicing are the switches, tubes and even caps have never been serviced or replaced.
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Post by darkarn on Nov 19, 2020 18:51:42 GMT
crappy tubes can have channel imbalance, some become more microphonic (tapping them is audible), some become more noisy, others may start sounding poorly, others may have 'flickering noise'. In the end tubes all fail. That said, I have my fathers old tube radio in my work room and sometimes switch it on. The darn thing is 60 years old and the only thing that needs servicing are the switches, tubes and even caps have never been serviced or replaced.
Wow, thanks! I didn't know that tubes can last that long too. I guess I shouldn't be that worried after all
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Post by darkarn on Nov 19, 2020 18:59:21 GMT
The volpots are with me now by the way. I have removed the old volpot and placed the new one using jumper cables (i.e. not soldered onto the PCB) just as a quick way to test the volpot. Will comment more on this once I test it out properly and also when I get the pictures of doing the repair out of my camera
Good news, I have tested the new volpot and can confirm that the audio is no longer being cut out and/or distorted
Bad news is that when listening to quieter audio (or simply no audio), I can hear some static sounds when the volpot is adjusted towards the end (especially starting from 9 o'clock position to the max). I have tried the following troubleshooting steps: 1. Different Cables: No difference 2. Different DACs: No difference 3. Different tubes: No difference 4. Swapping between headphones and speakers: Problem more obvious on headphones, especially left channel 5. Bypassing capacitors and/or resistors: No difference for all 4 different settings
May I know what should I do next?
As for pics, I will post them later
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solderdude
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Post by solderdude on Nov 20, 2020 6:14:50 GMT
As lomg as you hear 'something' while adjusting the volume only and no cutting out then it isn't a problem.
Do you have the Ember 2.1 (where you can set the input cap in 4 different positions) or the original Ember where you can only bypass the input cap ?
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Post by darkarn on Nov 20, 2020 13:42:09 GMT
As lomg as you hear 'something' while adjusting the volume only and no cutting out then it isn't a problem. Do you have the Ember 2.1 (where you can set the input cap in 4 different positions) or the original Ember where you can only bypass the input cap ?
I am using the Ember 2.1 where there are four positions for bypassing the capacitor and/or resistor. I have already tried all four positions and can still hear the scratching sounds towards the end of the volpot
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solderdude
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Post by solderdude on Nov 20, 2020 20:33:48 GMT
As long as it is quiet when the potmeter is not moved it is no problem.
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Crispy
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Post by Crispy on Nov 22, 2020 18:25:38 GMT
As lomg as you hear 'something' while adjusting the volume only and no cutting out then it isn't a problem. Do you have the Ember 2.1 (where you can set the input cap in 4 different positions) or the original Ember where you can only bypass the input cap ? I am using the Ember 2.1 where there are four positions for bypassing the capacitor and/or resistor. I have already tried all four positions and can still hear the scratching sounds towards the end of the volpot
I have just had a similar problem with the vol pot on my Kameleon portable amp. My solution was to remove the knob from the vol pot.
Turn the amp to face upwards and spray a few squirts of alcohol down the spindle.
I waited a couple of minutes to let the alcohol penetrate the pot, then rapidly turned the vol pot from low to high a few times.
Wiped away any excess alcohol and put the knob back on.
Left the unit overnight and tried it next day.
The volume pot is now completely quiet 
Hope this helps?
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