lol, I was expecting 'try replacing such and such cap'.
I am right in thinking you want me to put the old opamps back in?
Or did you mean put new ones in?
Either is good.
I am right in thinking you want me to put the old opamps back in?
Or did you mean put new ones in?
Either is good.
Ah, I see,
'short together pin 2 and pin 3 of both opamps (U7 and U8).'
So, the pads on the board, not the pins of the opamp.
TP6 19.7
TP7 19.8
TP9 19.6
TP10 9.7
'short together pin 2 and pin 3 of both opamps (U7 and U8).'
So, the pads on the board, not the pins of the opamp.
TP6 19.7
TP7 19.8
TP9 19.6
TP10 9.7
Yes, sorry that I wasn't totally clear there. TP6-9 not very promising so far. So what's the voltage on the pin2/3 and pin7 of each opamp?
Just to be absolutely sure, pin 1 is top left, going anti clockwise?
With no changes from the above results,
So, using TP0 yes?
U7 Pins 2,3,7 0.38V
U8 Pins 2,3,7 0.37V
With no changes from the above results,
So, using TP0 yes?
U7 Pins 2,3,7 0.38V
U8 Pins 2,3,7 0.37V
Yes, pin1 top left, increasing anti-clockwise. Voltages relative to TP0.
All 3 pins on each opamp exactly the same voltage? (I know 2 and 3 are connected but 7 isn't supposed to be the same).
Yellow LED still on? Please check the voltage (relative to TP0) on both sides of R62 and R40, seems to be something strange going on.
All 3 pins on each opamp exactly the same voltage? (I know 2 and 3 are connected but 7 isn't supposed to be the same).
Yellow LED still on? Please check the voltage (relative to TP0) on both sides of R62 and R40, seems to be something strange going on.
Yes, yellow light still on.
Redid one of the wire connections.
TP6,7,9 similar. TP10 now 6.8V
Checked the u7 and u8 pins again.
Does this now make a bit more sense?
U7 Pins
2 10.27V
3 10.27V
7 18.5V
U8 Pins
2 10.1V
3 10.1V
7 5.57V
closest to opamp furthest away
R62 10.25 18.3
R40 10.04 5.6
Redid one of the wire connections.
TP6,7,9 similar. TP10 now 6.8V
Checked the u7 and u8 pins again.
Does this now make a bit more sense?
U7 Pins
2 10.27V
3 10.27V
7 18.5V
U8 Pins
2 10.1V
3 10.1V
7 5.57V
closest to opamp furthest away
R62 10.25 18.3
R40 10.04 5.6
Yes that's now making more sense. I guess try putting a signal into the I2S and see if any music comes out.
👍
Well done.
I have sound.
The right channel is a LOT lower than the left.
As in, it is hard to tell there is anything there unless i unplug left channel and turn up volume.
But that might be something else I have done?
Well done.
I have sound.
The right channel is a LOT lower than the left.
As in, it is hard to tell there is anything there unless i unplug left channel and turn up volume.
But that might be something else I have done?
Let's check the U7,U8 pins with the I2S active. That'll check the quiescent conditions. With the original measurements (#267) the DAC contents was indeterminate.
Ah so now its clear there's an issue with the R channel. L looks OK. I wonder if the R channel MOSFET has blown (Q11) - check the voltage on pin8 of the DACs. Also check volts across R2 and recheck TP3.
Could be the problem is with Q3 and/or Q4 then. By your measurement R2 has 19.85-18.74 across it which is 1.11V. So definitely looks like Q3 is blown.
Excellent, thanks.
Swapped out Q3.
Sound from both speakers.
U7 pin 7 is now 9.74V
U8 pin 7 is 9.7V
Anything else I should test?
Swapped out Q3.
Sound from both speakers.
U7 pin 7 is now 9.74V
U8 pin 7 is 9.7V
Anything else I should test?
I can't think of anything else right now. I guess kick back and enjoy some music? Well done in rescuing your Kubelik from the jaws of death!
🙂
Awesome, thanks loads for your help, that was great.
So, should I now reverse all of the changes I made at the beginning?
Remove the wires, the short, replace the removed components and opamps?
It sounds interesting already and it is being powered from my (fairly cheap) bench power supply and I have wires criss crossing each other everywhere.
Awesome, thanks loads for your help, that was great.
So, should I now reverse all of the changes I made at the beginning?
Remove the wires, the short, replace the removed components and opamps?
It sounds interesting already and it is being powered from my (fairly cheap) bench power supply and I have wires criss crossing each other everywhere.
Why would you want to go backwards from a working DAC? What I would be interested to know is - how does this 'opampless' DAC sound compared to the original Kubelik? Based on my experiments it might well sound better than the original but almost certainly measures worse.
Ah, I see.
I thought this was a test to find what I fried and then replace it then return to its original form.
I also would like to know the comparison 🙂
I didn't get a single note from it before it ftsssded
I shall make another one at some point and compare for sure.
Even with it powered from my bench power supply and with the fan going from that, I do like the sound.
I don't know what words to use to compare it to my Khadas Tone Board.
I am looking forward to getting a proper psu sorted (i broke the regulator as well 🙁 )
I have some salvaged LM317s.
Anyway, I like it for sure.
It makes me smile. It is kind of a fuller sound. More depth or something. Clearer but warmer.
When I get a chance, I will see if I can work out a method of quickly swapping back and forth from the KTB to this.
I won't be putting it in permanently, that is for sure. This is definitely nicer.
Right, power for it. Then I really must get on with improving speakers.
Thanks loads for your everything. Designing, making it available, organising the kit, the price, the guide, the lovely labelling AND your help when I mess it up. All that and I get a nicer sound.
I thought this was a test to find what I fried and then replace it then return to its original form.
I also would like to know the comparison 🙂
I didn't get a single note from it before it ftsssded
I shall make another one at some point and compare for sure.
Even with it powered from my bench power supply and with the fan going from that, I do like the sound.
I don't know what words to use to compare it to my Khadas Tone Board.
I am looking forward to getting a proper psu sorted (i broke the regulator as well 🙁 )
I have some salvaged LM317s.
Anyway, I like it for sure.
It makes me smile. It is kind of a fuller sound. More depth or something. Clearer but warmer.
When I get a chance, I will see if I can work out a method of quickly swapping back and forth from the KTB to this.
I won't be putting it in permanently, that is for sure. This is definitely nicer.
Right, power for it. Then I really must get on with improving speakers.
Thanks loads for your everything. Designing, making it available, organising the kit, the price, the guide, the lovely labelling AND your help when I mess it up. All that and I get a nicer sound.
