Let me summary again: It's my first time tube amp so I don't dare to touch the HV ..lol...So I haven't tried to do the measurement yet.
Anyway, after I got the amp, it was working fine but still had small sound of thump on both channels, not as loud now
1st: Amp worked fine for a month before swapped the caps
2nd: -Swapped 4 Jantzen Audio 0.47uF 800V Z-Superior Capacitor
-Turned on, smell burning, then turn off, tried like 2 times more and the same happen, inspect around and didn't see anything bad -Swapped 12ax7 tubes, then it worked, so at first I thought bad tubes, played for few hours then tried to swap the other tubes again to check but it turned out working too. So I wasn't sure why the smell at first turn on. -Thump only 1 channel, so I don't think the higher value of the caps causing it
3rd:- -I tripped it out last night to check on both side of the PCB, didn't see points burn. Even used magnify glass to check on resistors to see if any is cracking/burning.
-All 4 bias pts are good at 0.50v since I checked everyday after 4 hours use -Both channels work fine except thump on 1 channel
I am gonna check it again while waiting for new caps. Do you know any good cheap voltage meter? I like to get one since I may need later.
Anyway, after I got the amp, it was working fine but still had small sound of thump on both channels, not as loud now
1st: Amp worked fine for a month before swapped the caps
2nd: -Swapped 4 Jantzen Audio 0.47uF 800V Z-Superior Capacitor
-Turned on, smell burning, then turn off, tried like 2 times more and the same happen, inspect around and didn't see anything bad -Swapped 12ax7 tubes, then it worked, so at first I thought bad tubes, played for few hours then tried to swap the other tubes again to check but it turned out working too. So I wasn't sure why the smell at first turn on. -Thump only 1 channel, so I don't think the higher value of the caps causing it
3rd:- -I tripped it out last night to check on both side of the PCB, didn't see points burn. Even used magnify glass to check on resistors to see if any is cracking/burning.
-All 4 bias pts are good at 0.50v since I checked everyday after 4 hours use -Both channels work fine except thump on 1 channel
I am gonna check it again while waiting for new caps. Do you know any good cheap voltage meter? I like to get one since I may need later.
I have a good ohm meter from 20 years ago lol but not sure it can measure the voltage. I will check again. I like to get voltage meter to check the cap only.
Original: thump both channels but sound not loud
Upgraded caps: thump only 1 channel, the other one is dead quiet.
So I am not sure the thump was causing the smelling cap or something else. The problem is the smelling cap is good now, doesn't smell anymore. So I am sure where to trouble-shooting next.
Original: thump both channels but sound not loud
Upgraded caps: thump only 1 channel, the other one is dead quiet.
So I am not sure the thump was causing the smelling cap or something else. The problem is the smelling cap is good now, doesn't smell anymore. So I am sure where to trouble-shooting next.
I agree with ian for the multimeter, you will find good on the internet.
however, I can not advise you too much to replace all the power capacitor.
I tell you that because of the 5 or 6 yaqin that I have seen in recent months, 100% of power capacitors were underestimated and of poor quality, or very degraded (I measured a 6800pF for 150uF ...).
No need to ruin yourself in high end brands, just good branded parts of the trade are perfect.
we can give you a good address to buy but you have to know in which corner of the planet you are.
however, I can not advise you too much to replace all the power capacitor.
I tell you that because of the 5 or 6 yaqin that I have seen in recent months, 100% of power capacitors were underestimated and of poor quality, or very degraded (I measured a 6800pF for 150uF ...).
No need to ruin yourself in high end brands, just good branded parts of the trade are perfect.
we can give you a good address to buy but you have to know in which corner of the planet you are.
That pcb has solder in plenty of places it should not be...
If not for the solder screen you might have a different issue. Also that track in the middle of the picture dc ones not look quite right.
If it were me I'd be fixing and cleaning th jose issues, as they will bite you one day
I am not saying there is a fault, but I do suggest you are more critical in your inspection and standard of "ok" on the soldering.
If not for the solder screen you might have a different issue. Also that track in the middle of the picture dc ones not look quite right.
If it were me I'd be fixing and cleaning th jose issues, as they will bite you one day
I am not saying there is a fault, but I do suggest you are more critical in your inspection and standard of "ok" on the soldering.
Some electrical components are sold on adhesive carrier tape. The adhesive is some rubber-like material that can smell when heated. Read this:
Dried Carrier tape for leaded capacitors/resistors, how to remove it ? - Page 1
Dried Carrier tape for leaded capacitors/resistors, how to remove it ? - Page 1
You can get free shipping from Digi-Key, which is a major supplier comparable to Mouser. Details here:
Free Shipping On Parts Orders | Audiokarma Home Audio Stereo Discussion Forums
I think I found the problem but need to double check everything. After replaced the cap, and got the cap meter check that found nothing wrong. Now I realized the color is different on resistor. Compare with the original images, it's absolutely missing the red color.
Both resistors have the same value so I guess the top one is burned. Will compare all resistors on both channels to see anything else is bad.
Both resistors have the same value so I guess the top one is burned. Will compare all resistors on both channels to see anything else is bad.
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Here was the original image that was working fine before
Probably the smell of burning came from that resistor. I am not sure if it's good or not. Replacing would prevent more damage in the future. I am gonna to take time to compare every single of them. Got the tool to measure the resistor now so I will check them. I am not comfortable to do the voltage check when the amp is on.
Probably the smell of burning came from that resistor. I am not sure if it's good or not. Replacing would prevent more damage in the future. I am gonna to take time to compare every single of them. Got the tool to measure the resistor now so I will check them. I am not comfortable to do the voltage check when the amp is on.
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I am not comfortable to do the voltage check when the amp is on.
Get adult supervision then.
There is no other way to tell if a resistor is dissipating more than it should.
Colour and temperature are not good indicators and neither is smell, after the capacitor olfactory fiasco
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