Richard,
I’ve finished the phono stage and power supply. AC and DC voltages through the power supply seem fine; however, there are anomalies with both of the circuit boards. Here are readings you suggest with IC3 and IC4 installed, and IC1 and IC2 not installed:
******************LEFT*******RIGHT
IN+ to IN-:************0********0
OUT+ to OUT-:*********0********0
GND to Pin 4 of IC1:****+11******+19
GND to Pin 7 of IC1:****-19******-11
V++ to V--:***********38******38
Look forward to your advice.
Thanks,
Warren
I’ve finished the phono stage and power supply. AC and DC voltages through the power supply seem fine; however, there are anomalies with both of the circuit boards. Here are readings you suggest with IC3 and IC4 installed, and IC1 and IC2 not installed:
******************LEFT*******RIGHT
IN+ to IN-:************0********0
OUT+ to OUT-:*********0********0
GND to Pin 4 of IC1:****+11******+19
GND to Pin 7 of IC1:****-19******-11
V++ to V--:***********38******38
Look forward to your advice.
Thanks,
Warren
2 transistors installed wrong, each board had matching transistors. Dumb mistake. Apparently still have problems, h'ever. Both boards now give identical readings: g & 4 = +17; g & 7 = -11; ++ to -- = 39. Tough to pull the transistors, might have damaged parts, but both boards give same readings.
Warren
Warren
The "E" marking on the board indicates the emitter, pin 1. Q2 is oriented 180 degrees with respect to Q1.
Though I'm a bit confused because it seems like the working positive X-reg you had before has is now not working.
Problem is at any rate isolated to Q1,2 ... worst case you have to replace them, but take the time to check everything again first, they might be just the wrong way round.
Rather than worrying about the pins of IC1,2 right now, you can just measure the X-reg output at the unused V+ and V- test pads. It will be the same value.
Though I'm a bit confused because it seems like the working positive X-reg you had before has is now not working.
Problem is at any rate isolated to Q1,2 ... worst case you have to replace them, but take the time to check everything again first, they might be just the wrong way round.
Rather than worrying about the pins of IC1,2 right now, you can just measure the X-reg output at the unused V+ and V- test pads. It will be the same value.
Attachments
Orientation & placement of transistors appears correct now. Original mistake was forgetting they were two separate part numbers. Reading instructions, emitter is left leg when facing printed side, legs down. Readings at (v+) - (v-) = 28 vdc.
Rember, I swapped only two transistors, would damaged parts explain this condition?
Thanks
Rember, I swapped only two transistors, would damaged parts explain this condition?
Thanks
BD135,137,139 are the npn, differing only in the voltage rating, BD136,138,140 are the equivalent pnp. All kits ship with BD135,136 pairs as Q1,2, but the schematic shows BD139,140 because that's what Eagle has as default and I didn't bother renaming.
"Rember, I swapped only two transistors, would damaged parts explain this condition?"
Not that I can see, no. The output value, or working condition of the positive X-reg will not effect the negative side, as the reference is taken off the input voltages V++ and V--.
As I understand (referenced to COM/ground) you have V+ +17V, V- -11V on one board, and V+ +17V, V- -11V on the other, and initially you had BD135 for both Q1,2 in one board and BD136 for Q1,2 in the other. The final result is that Q1 of both boards is damaged. Even if the transistors placed incorrectly are damaged, it doesn't add up.
Q1A BD135 [+11V] -> no change (correct, should give +11 V)
Q2A (BD135) [+19V] -> (BD136) (if damaged +17 V)
Q1B BD136 [-11V] -> no change (correct, should give -11 V)
Q2B (BD136) [-19V]-> (BD135) (if damaged -17 V)
Perhaps the simplest thing is for me to send you replacements...
"Rember, I swapped only two transistors, would damaged parts explain this condition?"
Not that I can see, no. The output value, or working condition of the positive X-reg will not effect the negative side, as the reference is taken off the input voltages V++ and V--.
As I understand (referenced to COM/ground) you have V+ +17V, V- -11V on one board, and V+ +17V, V- -11V on the other, and initially you had BD135 for both Q1,2 in one board and BD136 for Q1,2 in the other. The final result is that Q1 of both boards is damaged. Even if the transistors placed incorrectly are damaged, it doesn't add up.
Q1A BD135 [+11V] -> no change (correct, should give +11 V)
Q2A (BD135) [+19V] -> (BD136) (if damaged +17 V)
Q1B BD136 [-11V] -> no change (correct, should give -11 V)
Q2B (BD136) [-19V]-> (BD135) (if damaged -17 V)
Perhaps the simplest thing is for me to send you replacements...
I think your summary is correct, but let me recap just to be sure, I’m using right and left as reference.
Background: I forgot that there were two different transistor models and treated them as all being the same. My orientation has always been: when looking at the printed side of the transistor, and the legs are pointed down, the left leg is the emitter. Based on this assumption, the orientation has always been correct.
Initially, both bd136 were installed in the left board, both bd135 were in the right board. Readings were: Left, ground to pin 4, (+11), to pin 7, (-19). Right, ground to pin 4, (+19), to pin 7, (-11).
I swapped two transistors so that there is now one of each on each board, 135 in q1, 136 in q2. Readings now are: Left, ground to pin 4, (+17), to pin 7, (-11). Right, ground to pin 4, (+17), to pin 7 (-11).
Given the three in-line legs, I found it difficult to de-solder and remove the two transistors. It took more heat, force, and time than I liked. I could easily have cooked or damaged one or both. However, the two transistors that were correct were not touched.
Based on this, if you still think it best that I replace all four, let me know.
Thanks
Background: I forgot that there were two different transistor models and treated them as all being the same. My orientation has always been: when looking at the printed side of the transistor, and the legs are pointed down, the left leg is the emitter. Based on this assumption, the orientation has always been correct.
Initially, both bd136 were installed in the left board, both bd135 were in the right board. Readings were: Left, ground to pin 4, (+11), to pin 7, (-19). Right, ground to pin 4, (+19), to pin 7, (-11).
I swapped two transistors so that there is now one of each on each board, 135 in q1, 136 in q2. Readings now are: Left, ground to pin 4, (+17), to pin 7, (-11). Right, ground to pin 4, (+17), to pin 7 (-11).
Given the three in-line legs, I found it difficult to de-solder and remove the two transistors. It took more heat, force, and time than I liked. I could easily have cooked or damaged one or both. However, the two transistors that were correct were not touched.
Based on this, if you still think it best that I replace all four, let me know.
Thanks
Is it possible you made a mistake for the second set of measurements? Your report should have read, logically, for swapping Q2 of board 1 with Q1 of board 2-
"I swapped two transistors so that there is now one of each on each board, 135 in q1, 136 in q2. Readings now are: Left, ground to pin 4, (+11), to pin 7, (-17). Right, ground to pin 4, (+17), to pin 7 (-11)."
Simplest is just replace all four. I've sent you an email.
"I swapped two transistors so that there is now one of each on each board, 135 in q1, 136 in q2. Readings now are: Left, ground to pin 4, (+11), to pin 7, (-17). Right, ground to pin 4, (+17), to pin 7 (-11)."
Simplest is just replace all four. I've sent you an email.
I have two 24VA (2x12VAC) printtransformers (see link)
Would these be enough for a double mono powersupply?
Printtransformator, 12-0-12, 24VA - Transformatoren - Componenten & Elektronica onderdelen
Would these be enough for a double mono powersupply?
Printtransformator, 12-0-12, 24VA - Transformatoren - Componenten & Elektronica onderdelen
Hi,
I think they will be OK but you have to use one diode bridge because the transformer does not have two seperate secondary windings. As it is not a toroid transformer you have to be more carefull you do not introduce hum.
Ronald.
PS Als je me een email stuurt kan ik het je ook in het nederlands uit leggen. gr.
I think they will be OK but you have to use one diode bridge because the transformer does not have two seperate secondary windings. As it is not a toroid transformer you have to be more carefull you do not introduce hum.
Ronald.
PS Als je me een email stuurt kan ik het je ook in het nederlands uit leggen. gr.
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Two PSUs from two separate transformer-windings are independant of each other, 12-0-12 is like a siamese twin they always are connected to each other. I think it will not influence the sound. What will influence the sound is that they are rather small (24 VA). To start with they will be OK, you can allways upgrade later.
Ronald.
Ronald.