Looking at the schematic again, it appears that everything is probably OK from u2, pin 7 to the speaker terminals. The overall gain of the amp appears to be ~5.26. With an input of 3.6v, that would give you an output of 18-19v.
Pull Q3 to see if that allows the output to increase. If not, post the AC voltage on U2, pin 1 and U2, pin 14.
Pull Q3 to see if that allows the output to increase. If not, post the AC voltage on U2, pin 1 and U2, pin 14.
2xRCA
In 3,5 mV Out 170mV Gain = (170/3,5) ~48,57
10mV 610 mV Gain = 61
20mV 1210mV Gain = 60,5
40mV 2420mV Gain = 60,5
80mV 4960mV Gain = 62
160mV 9250mV Gain = 57,81
320mV 19350mV Gain = 60,47
640mV 16200mV Gain = 25,31
1xRCA
3,5mV 150mV Gain = 42,86
10mV 500mV Gain = 50
20mV 1025mV Gain = 51,25
40mV 1900mV Gain = 47,5
80mV 3900mV Gain = 48,75
160mV 7850mV Gain = 49
320mV 16000mV Gain = 50
640mV 17000mV Gain = 26,6
950mV 17000mV Gain = 17,9
In 3,5 mV Out 170mV Gain = (170/3,5) ~48,57
10mV 610 mV Gain = 61
20mV 1210mV Gain = 60,5
40mV 2420mV Gain = 60,5
80mV 4960mV Gain = 62
160mV 9250mV Gain = 57,81
320mV 19350mV Gain = 60,47
640mV 16200mV Gain = 25,31
1xRCA
3,5mV 150mV Gain = 42,86
10mV 500mV Gain = 50
20mV 1025mV Gain = 51,25
40mV 1900mV Gain = 47,5
80mV 3900mV Gain = 48,75
160mV 7850mV Gain = 49
320mV 16000mV Gain = 50
640mV 17000mV Gain = 26,6
950mV 17000mV Gain = 17,9
This is measurements taken tonight without removing Q3.
To me the gain seems to be quite ok? Average around 50x..
What is "normal" gain of an amp... I did not have the time
to remove Q3 tonight to se if the output rises.
Will try that asap. What i did when measuring this was first,
measure the VAC on the RCA intput plug, then connecting the
input. Ant the measuring the VAC on the speaker wires with the
speaker disconnected.
I think the VAC would decrease a litle when speaker is connected.
Does this say anything about the condition of the amp?
I will try again and play some music trough the stereo and se if
the gain still "comes to late".
I guess it will since i havent done anything with the amp from last time
except opening the case once again to do the measurements.
This sub is driving me nuts and the time isnt worth it but im fixing it
for a friend so its like, im glad if hes when he get it back and dont have to
throw it away, or axe it or something more funny
To me the gain seems to be quite ok? Average around 50x..
What is "normal" gain of an amp... I did not have the time
to remove Q3 tonight to se if the output rises.
Will try that asap. What i did when measuring this was first,
measure the VAC on the RCA intput plug, then connecting the
input. Ant the measuring the VAC on the speaker wires with the
speaker disconnected.
I think the VAC would decrease a litle when speaker is connected.
Does this say anything about the condition of the amp?
I will try again and play some music trough the stereo and se if
the gain still "comes to late".
I guess it will since i havent done anything with the amp from last time
except opening the case once again to do the measurements.
This sub is driving me nuts and the time isnt worth it but im fixing it
for a friend so its like, im glad if hes when he get it back and dont have to
throw it away, or axe it or something more funny
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