By supply voltage you mean the 12 volt / 15 volt DC range ?
We will have to check, I did notice some minus voltages on the multimeter and I asked about them but my father thought they were of no importance. If I remember correctly it was only on the smaller voltage values, but I could easily be wrong so we'll have to check.
Do we only have to check the pins with that measured in the 12 / 15 volt range or would you like us to check the pins with the millivolt ranges as well ?
We will have to check, I did notice some minus voltages on the multimeter and I asked about them but my father thought they were of no importance. If I remember correctly it was only on the smaller voltage values, but I could easily be wrong so we'll have to check.
Do we only have to check the pins with that measured in the 12 / 15 volt range or would you like us to check the pins with the millivolt ranges as well ?
In almost all preamp audio circuits, the audio op-amps should have both positive and negative supply voltage. It's generally in the range of ±10 to ±18v.
It's not necessary to post the voltage on the supply pins to the millivolt.
It's not necessary to post the voltage on the supply pins to the millivolt.
Alright we´ll measure the pins with the 10 to 18 volt range and tell you if any are in the minus range.
I know it´s not necessary (and kinda strange) but I thought I´d keep it simple by typing down everything in the same range instead of specifying which is millivolt and which is volts. 😎
I know it´s not necessary (and kinda strange) but I thought I´d keep it simple by typing down everything in the same range instead of specifying which is millivolt and which is volts. 😎
Let's see, I have negative and positive voltage on the following pins:
U9 PIN1 -4.5 V
U9 PIN7 +12.8 V
U4 PIN1 -14.2 V
U4 PIN8 +14.4 V
U1 PIN1 -13.7
PIN2 - 13
3 -13
4 - 14.2
5 -12
6 -12.7
7 -13.5
8 +14.4
U9 PIN1 -4.5 V
U9 PIN7 +12.8 V
U4 PIN1 -14.2 V
U4 PIN8 +14.4 V
U1 PIN1 -13.7
PIN2 - 13
3 -13
4 - 14.2
5 -12
6 -12.7
7 -13.5
8 +14.4
Are you sure that these are accurate?
Pin 1? did you mean pin 4?
-4.5v. Did you mean -14.5v?
If one end of R45 has 0v, I think U1 is defective.
Pin 1? did you mean pin 4?
-4.5v. Did you mean -14.5v?
If one end of R45 has 0v, I think U1 is defective.
I'm 99% certain it was 4.5 volt yes, will check it though.
By your question "pin1 ? did you mean pin4?" to which chip are you referring ? U9 or U4 ?
Will check R45.
Yes, my father's thought was also that U1 might be defective.
By your question "pin1 ? did you mean pin4?" to which chip are you referring ? U9 or U4 ?
Will check R45.
Yes, my father's thought was also that U1 might be defective.
That's a problem. It should have had the same negative voltage as the other op-amps in the area.
U9 PIN 1 definitely is -4.5 V DC.
The right side end of R45 has 13 volts DC.
The left side end of R45 has 7 millivolts DC.
The right side end of R45 has 13 volts DC.
The left side end of R45 has 7 millivolts DC.
7mv is essentially 0v (for this).
Replace U1 to see how that changes the voltage on the rest of the op-amps.
Replace U1 to see how that changes the voltage on the rest of the op-amps.
I currently only have OP275 and OPA2134PA in stock. I'll solder in a socket and put in one of these chips, see what happens.
I replaced U1 by a socket and another NE5534, amplifier still does not work properly.
Now one of both channels wasn't even producing sound, instead of very weak.
Stupid me, U1 is a NE5532 I now realise, not 5534
Will have to check whether I indeed used a 5534, in that case I'll test the amp again with a 5532 later on, when I go back to my father's place. Hopefully I did not damage anything by putting a wrong chip ? How about the chip itself ?
Now one of both channels wasn't even producing sound, instead of very weak.
Stupid me, U1 is a NE5532 I now realise, not 5534
Will have to check whether I indeed used a 5534, in that case I'll test the amp again with a 5532 later on, when I go back to my father's place. Hopefully I did not damage anything by putting a wrong chip ? How about the chip itself ?
Perry,
A thousand thanks, replacing the NE5532 by another NE5532 did it !
The amplifier powers on normally, nice idle, no POP ! and nice sound.
My friend, for whom I bought the amp, is very happy ! Got a nice amp with no previous damage / repairs in very nice exterior condition for a good price and almost zero repair costs.
THANKS !
Fred
A thousand thanks, replacing the NE5532 by another NE5532 did it !
The amplifier powers on normally, nice idle, no POP ! and nice sound.
My friend, for whom I bought the amp, is very happy ! Got a nice amp with no previous damage / repairs in very nice exterior condition for a good price and almost zero repair costs.
THANKS !
Fred
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