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Old 15th May 2012, 12:30 PM   #1991
rjm is offline rjm  Japan
Richard Murdey
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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...
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Old 15th May 2012, 01:06 PM   #1992
wanders is offline wanders  United States
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OK, but I'm going to send you a full recap in a couple of hours from my office computer ... to be sure you know everything I did.
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Old 15th May 2012, 05:00 PM   #1993
wanders is offline wanders  United States
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I think your summary is correct, but let me recap just to be sure, Iím 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
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Old 16th May 2012, 01:20 AM   #1994
rjm is offline rjm  Japan
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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.
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Old 16th May 2012, 01:23 AM   #1995
wanders is offline wanders  United States
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Thanks.
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Old 16th May 2012, 09:46 AM   #1996
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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
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Old 16th May 2012, 09:55 AM   #1997
kor952 is offline kor952  Netherlands
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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.

Last edited by kor952; 16th May 2012 at 10:02 AM.
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Old 16th May 2012, 10:00 AM   #1998
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Hi Ronald,

Thanks! The transformer has 12-0-12 secondary windings. Isn't that the same as two separate windings?

Jan
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Old 16th May 2012, 10:23 AM   #1999
kor952 is offline kor952  Netherlands
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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.
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Old 16th May 2012, 03:21 PM   #2000
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by wanders View Post
................... 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...........
This only applies to To126 & 2sa/c packages.

To220, To3p, To247 & To264 devices are the reverse of To126.

I am away to check 2sa/c.
Yes, 2s Pin out matches To126
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Last edited by AndrewT; 16th May 2012 at 03:25 PM.
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