STEG 75.6mx in protect

[Perry Babin]

Is R71 within tolerance?

 

[nino80]

it is signed as 180... i measured 19,2 OHM...

 

[Perry Babin]

I can't be sure but it appears that one end of that resistor connects to pin 13 and the other end to pin 15. Is this correct?

 

[nino80]

R71 is connected with PIN 5 and PIN 7...

on this site is the angle... according to datasheet (page 11) it goes from 1 to 8...

PIN 15 is on the other side second from top... 2 below PIN 13 with 13,68V.

 

[Perry Babin]

I can't follow it from the photos. Have you tried contacting the manufacturer for a schematic diagram?

 

[nino80]

yes, answer was "no way"

 

[Perry Babin]

OK, let's go at this from a different direction. Follow the circuit from the remote turn-on terminal. Where does it go, what does it connect to?

 

[nino80]

ok, here we go...


path of REMOTE

1st:

REM-terminal --> *R246 --> *R245 --> R244 --> PROTECT-LED...


2nd:

REM-terminal --> R248 --> *R249 --> *C132 --> U16, PIN 6.

 

[Perry Babin]

Post the voltage on all of the pins of the LM339.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:

 

[pergo]

Steg is(was) from Italy (my country) and it's failed
No italian's companies deliver schematic. They're very jealous.

Steg circuits are very uncommon. For example, the regulation in not the tipical "feedback" mode, but a feed-forward that caused a lot of problem as Eva said @post30: http://www.diyaudio.com/forums/power-supplies/65130-smps-control-loop-estability-3.html

Even the protect circuit, sometimes fails for nothing The protection circuit is in a small SIL card

 

[nino80]

The voltage on all of the pins of the LM339.

all in V DC

IC# U16

Pin 1: 0,076
Pin 2: 0,004
Pin 3: 13,67
Pin 4: 0,540
Pin 5: 0,076
Pin 6: 5,601
Pin 7: 2,225
Pin 8: 0,004
Pin 9: 0,076
Pin 10: 2,667
Pin 11: 0,002
Pin 12: 0,001
Pin 13: 0,269
Pin 14:2,667

 

[Perry Babin]

From the voltages, it appears that the 339 is working properly (although pin 14 isn't as high as I'd expect (but I really don't know how it's being used here).

What does pin 1 of this comparator connect to?

 

[nino80]

2 paths of PIN 1:

-PIN 1 it is bridged with PIN 5 (PIN 10 and PIN 14 also)...

-when i follow the other path it is blocked by a diode...


Output 2 (PIN 1) is used to calc Output 1 (PIN 2)... ?!?

 

[Perry Babin]

Do you know how to set your camera to macro mode?

 

[nino80]

thanks for the tip with the makro mode...

the remote - voltage comes directly from the bottom to measurement point in themiddle of DZ6 and R247.

 

[Perry Babin]

Does the diode connected to pin 1 connect to Q45?

What are the markings on the face of Q45?

 

[nino80]

yes, marking is "2Gp and then something like 4 times _ on top of each other"...

i just see another path over PIN 1 over R222...

 

[Perry Babin]

What is the DC voltage on all 3 terminals of Q45?

 

[nino80]

Q45:

top: 12,00 V
bottom left: 0,76 V
botom right: 4,36 V

 

[Perry Babin]

OK. Do you find any terminal of any component in this area that's directly connected to pin 15 of the 3525?