Where are we up to 🙂 Morning Sakis... today... it will work 😀
Easy one first. LTSpiceIV from here, Winodws or MAC as appropriate. Links at right of page.
Linear Technology - Design Simulation and Device Models
Methinks your speaker switch is OK. With the speaker switch set to A the speaker terminals should read short to chassis from the negative speaker terminals and each of the positive terminals should read "short" to the output of each amplifier as appropriate.
So where are we at ?
Easy one first. LTSpiceIV from here, Winodws or MAC as appropriate. Links at right of page.
Linear Technology - Design Simulation and Device Models
Methinks your speaker switch is OK. With the speaker switch set to A the speaker terminals should read short to chassis from the negative speaker terminals and each of the positive terminals should read "short" to the output of each amplifier as appropriate.
So where are we at ?
sakis! good morning sir. yes, that makes sense, and i see in the schematic that there are a couple of 40K resistors there that engage when that set of speakers are not in use. very good, thanks.
please ignore the readings for speaker terminals above. seems i did not remove the darn-nab speakers before i took the readings. like i said, "duhh".
now, does this seem right for the terminals?
speakers-
switch position "OFF"
speakers A
L+ = open
L- = 11 K
R+ = open
R- = 11 K
speakers B
L+ = open
L- = 11 K
R+ = open
R- = 11 K
switch position "SpeakersA"
speakers A
L+ = 200 K
L- = 0 (short)
R+ = 200K
R- = 0 (short)
speakers B
L+ = open
L- = 0 (short)
R+ = open
R- = 0 (short)
Switch position "SpeakersB"
speakers A
L+ = open
L- = 0 (short)
R+ = open
R- = 0 (short)
speakers B
L+ = 200 K
L- = 0 (short)
R+ = 200 K
R- = 0 (short)
Speaker position "A + B"
speakers A
L+ = 200 K
L- = 11 K
R+ = 200 K
R- = 11 K
speakers B
L+ = 11 K
L- = 0 (short)
R+ = 11 K
R- = 0 (short)
so, can i deduce from this that yes, indeed, when A + B is selected, the speakers are put in series, thus me not hearing anything from speakers A when in A+B position? and, can i deduce that the switch is fine?
aidan
please ignore the readings for speaker terminals above. seems i did not remove the darn-nab speakers before i took the readings. like i said, "duhh".
now, does this seem right for the terminals?
speakers-
switch position "OFF"
speakers A
L+ = open
L- = 11 K
R+ = open
R- = 11 K
speakers B
L+ = open
L- = 11 K
R+ = open
R- = 11 K
switch position "SpeakersA"
speakers A
L+ = 200 K
L- = 0 (short)
R+ = 200K
R- = 0 (short)
speakers B
L+ = open
L- = 0 (short)
R+ = open
R- = 0 (short)
Switch position "SpeakersB"
speakers A
L+ = open
L- = 0 (short)
R+ = open
R- = 0 (short)
speakers B
L+ = 200 K
L- = 0 (short)
R+ = 200 K
R- = 0 (short)
Speaker position "A + B"
speakers A
L+ = 200 K
L- = 11 K
R+ = 200 K
R- = 11 K
speakers B
L+ = 11 K
L- = 0 (short)
R+ = 11 K
R- = 0 (short)
so, can i deduce from this that yes, indeed, when A + B is selected, the speakers are put in series, thus me not hearing anything from speakers A when in A+B position? and, can i deduce that the switch is fine?
aidan
sakis, why 500R? i thought that the dummy loads available were all around 8 ohms, or 4 or 16.
and, mooly, drivers in, speakers out, output transistors connected, bias at 1K, variac at 0, fingers crossed, breath held, and...
aidan
and, mooly, drivers in, speakers out, output transistors connected, bias at 1K, variac at 0, fingers crossed, breath held, and...
aidan
loads are directly connected to the amp and supposed to be 8R
What i suggested is a speaker of 8 R IN SERIES with a resistor of 500 R to reduce current draw but still can listen to some music from the speaker
What i suggested is a speaker of 8 R IN SERIES with a resistor of 500 R to reduce current draw but still can listen to some music from the speaker
ahh, okay, thank you.beats watching a meter or scope when doing adjustments. you'd need a third eye LOL
Hold it there... that is measured from chassis to Re19, yes.
What is the voltage on the Qe7 end of Re19
OK.
Now as a confirmation and still reading from chassis what is the voltage at the junction of the 0.47 ohms (that's easily measurable on one end of R41 or R43)
Now as a confirmation and still reading from chassis what is the voltage at the junction of the 0.47 ohms (that's easily measurable on one end of R41 or R43)
1.2 volt sounds OK.
Big question... does the voltage across Qe7 vary with the pot. Reading to those points from chassis wont work because both points could be moving up and down together. Its got to be across Qe7.
What you got, maximum and minimum readings.
well, as usual the junction of those two resistors is easily discernable. on the board, not so much. i assume i can take the voltage off of either leg of either resistor, away from the emitter of either output transistor, right?
if so, it is .21V, and not affected by bias control
if so, it is .21V, and not affected by bias control
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