Wine Fridge Power Board

[budm]

Re: Wine Fridge Power Board

https://www.badcaps.net/forum/showpo...0&postcount=95
acornish added the pin numbers (in yellow) in my picture.

[keeney123]

Re: Wine Fridge Power Board

[QUOTE=fzabkar;592009]Keeney123 assigned the numbers, not me.

https://www.badcaps.net/forum/attach...9&d=1437778674

Yes, that's it![/Q

I do not see any numbers I assigned to the transformers on my schematic.

[fzabkar]

Re: Wine Fridge Power Board

How did you assign which one to be pin 1 in my drawing so I can see what you are saying?

Keeney123 assigned the numbers, not me.

https://www.badcaps.net/forum/attach...9&d=1437778674

The topology is similar to this:
http://danyk.cz/s_atx01h.png

Yes, that's it!

[budm]

Re: Wine Fridge Power Board

How did you assign which one to be pin 1 in my drawing so I can see what you are saying?
There are 5 pins on the left side, 3 pins on the right side.
I think I see where my mistake is, one of the Gate drive winding should not be connected to GND, I have one end of both Gate drive windings connected to GND so that is wrong. I should have caught that if I draw up the schematic like Keeney suggested in the beginning, sorry.
The topology is similar to this:
http://danyk.cz/s_atx01h.png

http://danyk.cz/s_atx_en.html

[fzabkar]

Re: Wine Fridge Power Board

The windings on the transformer appear to have been drawn incorrectly. That's the source of the error.

AISI pins 3 & 4 are the winding that drives the middle transistor whereas 1 & 2 drives the outside one. So the winding that is drawn between pins 1 & 4 should actually run between pins 3 & 4.

In any case it's impossible to determine the actual layout simply by visual inspection. That's why a measurement is necessary.

[keeney123]

Re: Wine Fridge Power Board

The question can easily be resolved with a simple measurement by dunkel. What is the resistance between the +ve terminal of C13 and B-, and what is the resistance between the +ve terminal of C13 and the emitter of T7?

So you don't want to verify my schematic by the board from which is was drawn from?

[fzabkar]

Re: Wine Fridge Power Board

The question can easily be resolved with a simple measurement by dunkel. What is the resistance between the +ve terminal of C13 and B-, and what is the resistance between the +ve terminal of C13 and the emitter of T7?

[keeney123]

Re: Wine Fridge Power Board

OK so you draw the schematic from the given circuit and see what you get.

[fzabkar]

Re: Wine Fridge Power Board

Here is a PSU circuit that uses two MJE13007 transistors in a similar configuration:

http://320volt.com/wp-content/upload...e13007-v13.png

The diodes in the base circuit are general purpose signal types (1N4148). The polarities of the diodes and electrolytics match the circuit drawn by keeney123. However, the positions of the windings confirm that there is an error in our circuit diagram. Note that there is also a missing B- reference at the emitter of Q2 in the ATX circuit. :-)

[fzabkar]

Re: Wine Fridge Power Board

You can calculate the maximum design output of the PSU by measuring the resistances in each of the potential dividers attached to pins 1 and 2 of the TL494. If the figure turns out to be 12V, then that would point to unsuitable Peltiers. Alternatively, if you want to crank up the voltage, you could increase the value of either of the two resistors in the upper part of the potential divider attached to pin 2 of the TL494.

[keeney123]

Re: Wine Fridge Power Board

The MJE13005G appears to be similar in specs to the others:

https://cdn.badcaps-static.com/pdfs/...8910f762a5.pdf

Its pinout is BCE (left to right). The MJE13007 is a higher current, higher wattage version of the MJE13005G, so ISTM that it should be a good choice, provided that the pinout is correct. Just make sure to use heatsink insulation if necessary. I also notice that neither transistor has a CE diode, so that explains the one on the PCB.

Yes, I remember replacing this on the board I had, it can be done with the MJE13007. Of course I modified the board to try and get more power out of it because I thought the power supply was not driving hard enough because the inline current measurement only got to 2.4 Amps at 12V per Peltier. Bud M kept telling me to use a 12volt car battery to see if the Peltiers would drive harder. He was right. Although, I used an 12V ATX directly to the Peltiers and they would not drive more than 2.4 Amps. I left this set up over night and the temperature only got to 68 F.

[fzabkar]

Re: Wine Fridge Power Board

The MJE13005G appears to be similar in specs to the others:

https://cdn.badcaps-static.com/pdfs/...8910f762a5.pdf

Its pinout is BCE (left to right). The MJE13007 is a higher current, higher wattage version of the MJE13005G, so ISTM that it should be a good choice, provided that the pinout is correct. Just make sure to use heatsink insulation if necessary. I also notice that neither transistor has a CE diode, so that explains the one on the PCB.

[dunkel]

Re: Wine Fridge Power Board

If there is no TO92, then I can't see the purpose of IC3. AISI, IC3 has a single output but no inputs, yet it controls the TL494 in some way ???

I understand where R35 and R36 go. I want to know where R34 goes. In the diagram it connects to B- via the transformer winding. I believe that the other end of the transformer winding should connect to the emitter of T7, not B-.

As for your question regarding the transistor, please tell us the pinout of the original transistors. Is it BCE or ECB, and have you confirmed that it tests like an NPN transistor, not a MOSFET?

OK, let me remove the transistor to check the BCE or ECB and also my D12 to realize the D10.

did you see my picture I dont have TO92, nor even the empty space for it. thanks

[fzabkar]

Re: Wine Fridge Power Board

If there is no TO92, then I can't see the purpose of IC3. AISI, IC3 has a single output but no inputs, yet it controls the TL494 in some way ???

I understand where R35 and R36 go. I want to know where R34 goes. In the diagram it connects to B- via the transformer winding. I believe that the other end of the transformer winding should connect to the emitter of T7, not B-.

As for your question regarding the transistor, please tell us the pinout of the original transistors. Is it BCE or ECB, and have you confirmed that it tests like an NPN transistor, not a MOSFET?

[dunkel]

Re: Wine Fridge Power Board

This is my IC3

[dunkel]

Re: Wine Fridge Power Board

I can't identify the transistor. I found two candidates with similar specs, but they have different pinouts. I don't know if the difference is real, or whether there is an error in the datasheet. IME the BCE pinout is the commonest one.

BTW, the circuit diagram is drawn with FETS, but the markings suggest that T6 and T7 are NPN transistors. Can you confirm this by testing the B-E and B-C junctions with your meter's diode test? This will also verify the pinout.

What is also strange is that there are diodes between C-E (or D-S) in the circuit, but each of my candidates has an integrated C-E diode.

STT13005D, STMicroelectronics, fast switching NPN transistor, 2A, 700V, Veb = 9V, hfe(min) = 8, SOT-32, integrated CE diode:


APT13005D, Diodes Inc, 700V, 4A, Veb = 9V, hfe = 8, integrated CE diode:

STT13005D APT13005D

|-----|   |-----|
| O |   | O |
|_____|   |_____|
 | | |    | | |
 | | |    | | |
 E C B    B C E

As for D12 and D10, I would think that they would need to be fast switching diodes. ISTM that a current rating of 1A would be more than enough.

max base current = IC(max) / hfe(min) = 4A / 8 = 0.5A

Can you tell us the markings on the TO92 device next to IC3?

Can you also tell us the resistance between R34 and the source/emitter pin of T7? I believe there may be an error in the circuit diagram in this area.

Hello, I cant find any TO92.

and I think the resistance in the emitter of T7 is my R36

R35 goes to the Base )having in mind this transistor is like the BUL39Q i think i found as replacement but I also wanted to know if i can change it to MJE13007 because on the same thread i found i can use both but now im not sure.

[fzabkar]

Re: Wine Fridge Power Board

I can't identify the transistor. I found two candidates with similar specs, but they have different pinouts. I don't know if the difference is real, or whether there is an error in the datasheet. IME the BCE pinout is the commonest one.

BTW, the circuit diagram is drawn with FETS, but the markings suggest that T6 and T7 are NPN transistors. Can you confirm this by testing the B-E and B-C junctions with your meter's diode test? This will also verify the pinout.

What is also strange is that there are diodes between C-E (or D-S) in the circuit, but each of my candidates has an integrated C-E diode.

STT13005D, STMicroelectronics, fast switching NPN transistor, 2A, 700V, Veb = 9V, hfe(min) = 8, SOT-32, integrated CE diode:


APT13005D, Diodes Inc, 700V, 4A, Veb = 9V, hfe = 8, integrated CE diode:

STT13005D APT13005D

|-----|   |-----|
| O |   | O |
|_____|   |_____|
 | | |    | | |
 | | |    | | |
 E C B    B C E

As for D12 and D10, I would think that they would need to be fast switching diodes. ISTM that a current rating of 1A would be more than enough.

max base current = IC(max) / hfe(min) = 4A / 8 = 0.5A

Can you tell us the markings on the TO92 device next to IC3?

Can you also tell us the resistance between R34 and the source/emitter pin of T7? I believe there may be an error in the circuit diagram in this area.

[keeney123]

Re: Wine Fridge Power Board

Updated schematic as of dunkel observation of his board. Value resistor changed R 34, R35 and R36

[keeney123]

Re: Wine Fridge Power Board

according my resistors and the pictures, i get this:

R34 10ohms 5%
R35 2ohms 5%
R36 2.7kohms 5%

R35 = R38
R34 = R37
R36 = R39

I will add these values to my schematic. If you find out they are different please tell me.

[dunkel]

Re: Wine Fridge Power Board

according my resistors and the pictures, i get this:

R34 10ohms 5%
R35 2ohms 5%
R36 2.7kohms 5%

R35 = R38
R34 = R37
R36 = R39