I have an older spitznagel PCB transformer that has gone bad on an AC board for a grid tie inverter.
I cannot locate an exact replacement, but before I install something "close", I have questions about how this transformer was originally being used, because the circuitry does not seem to match the markings on the transformer.
The transformer says the 13.5v secondary pins are positions 5&6, and there are blind pins at 9&10. This is where the confusion lies. The circuit has a resistor placed across pins 9&10. If they are blind (no connection internally), why?
Here are images of the transformer:
Here is a picture of the board showing the secondary output side:
Here is a schematic I put together from what I see on the board:
The board is multilayer with a wide plane on the backside, but doing the best I can with a light, I am not seeing traces extend beyond the 9&10 resistor. I have also done some continuity scouting with a multimeter and not found that these pins are connected to anything else.
I'm not able to get much from the transformer since it seems cooked. The case is swollen and slightly browned on top, and the epoxy is swollen on the bottom with a small crack across it. The primary does not show any resistance to 20Mohms. The secondary shows 88 ohms. The blind pins show open. When I apply 240 to the primary I see nothing across the secondary or the blind pins. However, I do see about 3 volts from the secondary to either of the blind pins. Either 5 to (9 or 10), or 6 to (9 or 10) produce the same ~3v. This doesn't make sense, so I'm thinking the windings are shorted.
Here is info from Spitsnagel on this type of transformer. My older transformer (014 1200) is not listed.
http://www.spitznagel-gmbh.de/pcb-transformers-spk014.html
http://www.spitznagel-gmbh.de/userfiles/file/Spitznagel_B014_09.pdf
I have a second inverter board that is working. The voltage on pins 5&6 under load (at the resistors) is 20v. In the board photo, you can see a 2 pin header. That's on the load side of the resistors - maybe a TP. Anyway, it's 1.3v on the load side of those resistors.
So here are my questions for anyone that wants to take a stab at one or more of these:
1. Why was the resistor added across pins 9&10?
2. Do you know of a source for this older Spitznagel transformer or a functional equivalent?
I don't care about it's form or size, but this transformer is part of an 240v line power quality sensing circuit. I need to match it as closely as possible.
3. On the working unit, how did the secondary get to be 20v? Is it possible the transformer is very lightly loaded, and therefore I'm seeing a no load voltage? According to the Spitznagel pdf above, the no load voltage of a 12v transformer is 18.5v, so it would follow that a 13.5 transformer would show 20v no load. Or, is it something else?
I cannot locate an exact replacement, but before I install something "close", I have questions about how this transformer was originally being used, because the circuitry does not seem to match the markings on the transformer.
The transformer says the 13.5v secondary pins are positions 5&6, and there are blind pins at 9&10. This is where the confusion lies. The circuit has a resistor placed across pins 9&10. If they are blind (no connection internally), why?
Here are images of the transformer:
Here is a picture of the board showing the secondary output side:
Here is a schematic I put together from what I see on the board:
The board is multilayer with a wide plane on the backside, but doing the best I can with a light, I am not seeing traces extend beyond the 9&10 resistor. I have also done some continuity scouting with a multimeter and not found that these pins are connected to anything else.
I'm not able to get much from the transformer since it seems cooked. The case is swollen and slightly browned on top, and the epoxy is swollen on the bottom with a small crack across it. The primary does not show any resistance to 20Mohms. The secondary shows 88 ohms. The blind pins show open. When I apply 240 to the primary I see nothing across the secondary or the blind pins. However, I do see about 3 volts from the secondary to either of the blind pins. Either 5 to (9 or 10), or 6 to (9 or 10) produce the same ~3v. This doesn't make sense, so I'm thinking the windings are shorted.
Here is info from Spitsnagel on this type of transformer. My older transformer (014 1200) is not listed.
http://www.spitznagel-gmbh.de/pcb-transformers-spk014.html
http://www.spitznagel-gmbh.de/userfiles/file/Spitznagel_B014_09.pdf
I have a second inverter board that is working. The voltage on pins 5&6 under load (at the resistors) is 20v. In the board photo, you can see a 2 pin header. That's on the load side of the resistors - maybe a TP. Anyway, it's 1.3v on the load side of those resistors.
So here are my questions for anyone that wants to take a stab at one or more of these:
1. Why was the resistor added across pins 9&10?
2. Do you know of a source for this older Spitznagel transformer or a functional equivalent?
I don't care about it's form or size, but this transformer is part of an 240v line power quality sensing circuit. I need to match it as closely as possible.
3. On the working unit, how did the secondary get to be 20v? Is it possible the transformer is very lightly loaded, and therefore I'm seeing a no load voltage? According to the Spitznagel pdf above, the no load voltage of a 12v transformer is 18.5v, so it would follow that a 13.5 transformer would show 20v no load. Or, is it something else?