Did you check all junctions to confirm that they were intact and none had any leakage?
With no Vbe, the collector should not conduct and the base should be pulled down to near -45v if one LED is open.
Desolder one of the series LEDs and see how the voltage on those 2 transistors changes.
The regulator could be defective but let''s deal with one problem at a time.
With no Vbe, the collector should not conduct and the base should be pulled down to near -45v if one LED is open.
Desolder one of the series LEDs and see how the voltage on those 2 transistors changes.
The regulator could be defective but let''s deal with one problem at a time.
Yes I checked all junctions and none of both transistors was leaking.
By desoldering the LEDs the voltage did not changed.
I decide to reflow all transistors and replace the LEDs again, and now all 3 LEDs lit up, and nothing getting abnormally hot but i'm still having 11 DC volt at speakers terminal and voltage to those 2 transistor changed.
44.72V
31.10V
44.26V
40.91V
-9.96V
31.19V
By desoldering the LEDs the voltage did not changed.
I decide to reflow all transistors and replace the LEDs again, and now all 3 LEDs lit up, and nothing getting abnormally hot but i'm still having 11 DC volt at speakers terminal and voltage to those 2 transistor changed.
44.72V
31.10V
44.26V
40.91V
-9.96V
31.19V
Did you confirm the connections of those two transistors with your meter to confirm that they were the two 1070s next to the series connected LEDs?
That would mean that the collector of the top 1070 would have its collector directly connected to the emitter of the bottom transistor. If so, their voltage would have to be identical. They are not for the numbers you posted.
Also, the bottom 1070 has a Vbe of 10v. That means that the b-e junction is damaged.
Also, the bottom 1070 has a Vbe of 10v. That means that the b-e junction is damaged.
Top transistor collector : 31.10V
Bottom transistor emitter : 31.19V
If I mesure both quick enough, I mesure the exact same voltage across both,
As amp heating up the voltage changes a little bit and by the time I measure and note each voltage the voltage has slightly changed but, top collector and bottom emiter are at same voltage.
What would be the best replacement for KTA1070?
Would KSA1142 be okay?
Should I replace both of them?
I just found that 100 ohm resistor for the top transistor has blown open when I have powered the amp on
That might be me writing it wrong for you. I was writing voltage with the pin layout of the "transistor facing to me"
But the pin layout is
1 emitor
2 collector
3 base
So that case it will be.
1 44.26v
2 31.10V
3 44.72V
1 31.19V
2 - 9.96V
3 40.91V
The resistance of pin 2 top transistor and pin 1 bottom transistor are 0.001 ohm at my multimeter, so it's connected together.
Sorry about that. Does it make more Sense?
You need to look at the face of the transistor, legs down, post left to right.
Look at the datasheet:
https://pdf1.alldatasheet.com/datasheet-pdf/view/69651/KEC/KTA1070.html
Look at the datasheet:
https://pdf1.alldatasheet.com/datasheet-pdf/view/69651/KEC/KTA1070.html
I was wondering why pin 6 (in - ) was at -11V since it has no input, so I tested both transistors BC850B who tested ok, but I found that at the 620 ohm resistor, one side of the resistor was at -45V and the other -35V and varying a little bit. I tested the transistor BC846B which was ok, tested the resistor and it was okay too. I decided to reflow that resistor and I saw that it was broken in haft, I wonder why I was still reading 620ohm at my multimeter. I replaced that resistor and that was it. No more -11V at speaker terminal and the amp working perfecly fine now.
Thank you Perry and Moer for the diagram, that was helpful.
I have a last question, while replacing the resistor, I did melt the plastic casing the 0.1uf cap, it still work fine but I will replace it for peace of mind. Do you know the size / lead spacing for it? I don't have anything to mesure it right now.
Thank you Perry and Moer for the diagram, that was helpful.
I have a last question, while replacing the resistor, I did melt the plastic casing the 0.1uf cap, it still work fine but I will replace it for peace of mind. Do you know the size / lead spacing for it? I don't have anything to mesure it right now.
Pin 6 is feedback from the speaker output and will have approximately the same voltage as you see on the speaker terminal.
If you don't have a dial caliper, you can use the terminal spacing of any of the semiconductors (dimensions in their datasheets). The easiest are the ICs. The DIP ICs have a pin spacing of 0.1". The SOIC ICs have a pin spacing of 0.05".
If you don't have a dial caliper, you can use the terminal spacing of any of the semiconductors (dimensions in their datasheets). The easiest are the ICs. The DIP ICs have a pin spacing of 0.1". The SOIC ICs have a pin spacing of 0.05".