as shown several times, rails current loading of DEF is far from symmetrical/equal
mosfet working very hard (big current swing) while SIT working in counter-phase, and speaker is getting difference of their current (not sum as in normal A Class amps)
that's why I wrote ∀ Class on pcb
mosfet working very hard (big current swing) while SIT working in counter-phase, and speaker is getting difference of their current (not sum as in normal A Class amps)
that's why I wrote ∀ Class on pcb
Here is a picture of my 20+ years old 103dB speakers: My speakers
i was forced to learn how to build quiet electronics due to my sensitive speakers. With less sensitive speakers, it is possible to ignore many of the things that I implement and still not hear any noise or hum, but with my speakers, would be audible.
Twisting wires with their returns, and that include the output of bipolar supplies with their V+ V- Gnd, is done to reduce electromagnetic interference (EMI) pickup and also to reduce electromagnetic radiation from the wires. Twisted Pairs
Electrons in wires flow in loops to form circuits. For instance, electrons flow from the AC input to the power transformer and back to the AC input. Twist those wires. Electrons flow from the power supply out to the amplifier board and then back to the power supply. Twist those wires. Electrons flow from the amplifier board out to the speakers and back to the amplifier board. Twist those wires. Electrons flow from the audio signal source to the amplifier board and back to the signal source. Twist those wires.
Some very useful information by diyAudio member Bonsai:
Hifisonix-Ground Loops
Ground Loops pdf
i was forced to learn how to build quiet electronics due to my sensitive speakers. With less sensitive speakers, it is possible to ignore many of the things that I implement and still not hear any noise or hum, but with my speakers, would be audible.
Twisting wires with their returns, and that include the output of bipolar supplies with their V+ V- Gnd, is done to reduce electromagnetic interference (EMI) pickup and also to reduce electromagnetic radiation from the wires. Twisted Pairs
Electrons in wires flow in loops to form circuits. For instance, electrons flow from the AC input to the power transformer and back to the AC input. Twist those wires. Electrons flow from the power supply out to the amplifier board and then back to the power supply. Twist those wires. Electrons flow from the amplifier board out to the speakers and back to the amplifier board. Twist those wires. Electrons flow from the audio signal source to the amplifier board and back to the signal source. Twist those wires.
Some very useful information by diyAudio member Bonsai:
Hifisonix-Ground Loops
Ground Loops pdf
The Avantgarde speakers look amazing!
Here’s another paper on things that cause noise in circuits and ways to suppress it. I found this online via Google. It’s really more of a college course guide than it is a paper. The document seems to stand on its own with out the lecture.
https://www.ewh.ieee.org/r5/denver/rockymountainemc/archive/2004/October/Experimental_Demo.pdf
I finally got around to changing R18 and R19 to the right ones. The right channel is behaving as it should, I am listening to it right now.
The left channel is still not working. Even with the recommended setting of the pots I have already a current on the positive rail and even more on the negative rail but without the SIT or MOS getting warm. I checked all the zeners working and resistors for correct values. The only part getting warm is the 7805. 🤔
The left channel is still not working. Even with the recommended setting of the pots I have already a current on the positive rail and even more on the negative rail but without the SIT or MOS getting warm. I checked all the zeners working and resistors for correct values. The only part getting warm is the 7805. 🤔
I'll go back and re-read your posts, but not before tomorrow evening
did you tried moving SIT from confirmed channel to non-functional one?
all you need is to keep confirmed channel non-powered, to desolder wires to its SIT, then connect it to other channel with long wires; keep gate resistor soldered ditto to gate
did you tried moving SIT from confirmed channel to non-functional one?
all you need is to keep confirmed channel non-powered, to desolder wires to its SIT, then connect it to other channel with long wires; keep gate resistor soldered ditto to gate
@Zen Mod I wired the SIT from the non-functional channel to the functional channel and it powered up working like a charm which means the SITs are both working and my left board is somehow disfunctional. I see now you wrote to wire the functional SIT to the non-functional channel, but I guess this proves the same? If you have suggestions what to check, measure or photograph, I am very grateful.
extremely carefully , to not make short somewhere, check 5V value at 7805 ref
how to: when numbers are at you, pins down, most left is IN, mid pin is GND, most right is OUT (5V)
put black probe anywhere where you have GND, carefully put red probe to right pin
inform here
also confirm proper orientation of optocoupler on pcb
how to: when numbers are at you, pins down, most left is IN, mid pin is GND, most right is OUT (5V)
put black probe anywhere where you have GND, carefully put red probe to right pin
inform here
also confirm proper orientation of optocoupler on pcb
Right pin 4,97V, left 23,9V.
I have 136mV on the positive rail across the R of the CRC and almost 7V on the negative rail with the Iq turned all the way down.
Optocoupler:
I have 136mV on the positive rail across the R of the CRC and almost 7V on the negative rail with the Iq turned all the way down.
Optocoupler:
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R18 and R19, confirm (amp off) they're properly soldered
left side pin of R19 , in contact with pin 3 of opto
right side pin of R18 in contact with pin 4 of opto
pin 2 of optocoupler looks bare, but I resume it's soldered good enough from bottom side; confirm with buzz test that pin 2 is having connection with GND
can't see on picture, hope that left ACS chip is having dot equally oriented as right one?
left side pin of R19 , in contact with pin 3 of opto
right side pin of R18 in contact with pin 4 of opto
pin 2 of optocoupler looks bare, but I resume it's soldered good enough from bottom side; confirm with buzz test that pin 2 is having connection with GND
can't see on picture, hope that left ACS chip is having dot equally oriented as right one?
R18 and R19 ok
Pin 2 opto connects to ground, but(!) pin 4 also buzzes to ground?
ACS chips seem the same orientation came pre-soldered I think.
Pin 2 opto connects to ground, but(!) pin 4 also buzzes to ground?
ACS chips seem the same orientation came pre-soldered I think.
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other channel, opto , pin 4 - compare behavior to buzz test
slight/short buzz is OK, due to cap between gates (opto pin3 and 4) and cap to autoformer, but constant buzz is no-no
slight/short buzz is OK, due to cap between gates (opto pin3 and 4) and cap to autoformer, but constant buzz is no-no
remove/desolder opto
because it is suspicious, you can do it with cutting pins close to body, then desoldering them one by one, and cleaning pads with solder pump .... avoiding need to dismantle pcb from heatsink to get to back side
when empty, check buzz pin 4 pad
obtain new opto , solder in
dunno, you had 3K resistor in place of 36K, but that can't be a reason of opto going dodo
I mean - cleanest way of finding what is wrong would be - remove pcb from heatsink, desolder opto without ruining it, then check opto with diode/buzz test; if opto is Dodo, there will be short between pin 4 and pin 2 ( which is ditto soldered to GND) and pcb without opto in place should be free of GND on pin 4 pad
in any case - you can choose - longer way with chance of having nondamaged opto in hands in case of pcb trace being culprit ....... or shorter way, but needing to obtain new opto
because it is suspicious, you can do it with cutting pins close to body, then desoldering them one by one, and cleaning pads with solder pump .... avoiding need to dismantle pcb from heatsink to get to back side
when empty, check buzz pin 4 pad
obtain new opto , solder in
dunno, you had 3K resistor in place of 36K, but that can't be a reason of opto going dodo
I mean - cleanest way of finding what is wrong would be - remove pcb from heatsink, desolder opto without ruining it, then check opto with diode/buzz test; if opto is Dodo, there will be short between pin 4 and pin 2 ( which is ditto soldered to GND) and pcb without opto in place should be free of GND on pin 4 pad
in any case - you can choose - longer way with chance of having nondamaged opto in hands in case of pcb trace being culprit ....... or shorter way, but needing to obtain new opto