YG972S6 testing 6.74 mega ohms?

[klein]

hi
i have a question about a silicone ic chip, chip # YG972S6, using my dvm on check diode setting i get nothing both ways if i go to ohms i get nothing and 6.74 mega ohms. i'm checking it because while bench testing this power supply 32power500 i saw a wisp of smoke and when i turned the board over this was hot hot to the touch, i replaced most of the caps on this board because they were bulging, now on pins marked 12v i only get 9.35 and on 3.3v i get 1.3v .



i can' seem to find the pdf for YG972S6

[i4004]

Re: YG972S6 testing 6.74 mega ohms?

show some pics.

because

->chips are not checked by measuring diode test with dmm(and what pins did you cjeck anyway? is it a chip with 2 legs only? heh)

->if it got rather hot chances are it's done ("done" like "meduim rare"...heh)
if it's done, it should be changed.

[klein]

Re: YG972S6 testing 6.74 mega ohms?

hi
i'v been busy working on other things but now i have time to work on this project here are the pic's and a pic of the chip . the red circles are where i took the chip from top and bottom.

[Bobdee]

Re: YG972S6 testing 6.74 mega ohms?

hi
i'v been busy working on other things but now i have time to work on this project here are the pic's and a pic of the chip . the red circles are where i took the chip from top and bottom.

Hello Klein
I have just read on a Russian link that this rectifier is a 10A 600V
Thought this may help you in a replacement
Heres the link
http://translate.google.co.uk/transl...%3Den%26sa%3DG
Bob

[Toasty]

Re: YG972S6 testing 6.74 mega ohms?

Cap you replaced in backwards somewhere? Double check.

Schottky diode. High frequency switching.

Check the MOSFET and the Bridge rectifier mounted on the heatsink. Down and to the right on the top-down picture; next to C21-C22.

What is the device on the same heatsink just up from this diode? Marked U22.

Also, what is on the backside of the heatsink right behind this diode? I see something soldered across the circuit trace to this diode.

For future reference. Mains cap wiring - Red wire is usually used for positive, Black is negative.

Toast

[klein]

Re: YG972S6 testing 6.74 mega ohms?

just behind the heat sink is a small cap blue 471 1 kv and it is in parallel with the diode on the heat sink

F9222L regulator IC is u2 and it looks like it is smoked , i checked all the caps and i think they are in right looks like it, think i'm going to replace the f9222l.

so you think the YG972S6 diode is good ?

[Toasty]

Re: YG972S6 testing 6.74 mega ohms?

Diode is a high speed diode, not a Schottky. Should give correct reading on diode test function. You are correct, it's likely that it's bad. The diode is in series with the mains cap (+) and it feeds directly to U2 pin 23. Since R34 doesn't appear to be burnt, the only other current draw I can see is U2.

Datasheet for diode:
http://www.fujisemicon-elis.com/en/d...ON_NAME=search

Some digging with the specs in hand on Digikey reveals a good match:
http://search.digikey.com/scripts/Dk...5ETX06FPPBF-ND

The F9222L is available from B&D Enterprises and Audio Lab of Georgia:
http://www.bdent.com/search/part.jsp?partnum=F9222L ~$21
http://audiolabga.com/mal_cart/mal_cart.php?find=F9222L ~$8

Since there is no pinout available for U2, you'll have to check what it's driving for problems. You could pop the new one if driven components are bad.

Toast