Identify dil 14pin

[najrao]

I have to decipher this: all legend is sanded off.
Pin 12 is gnd or Vcc(-). Pin 4  is fed directly at 12V(+). All others are difficult to trace.
It is NOT a 084 or 324, but must be some other analogue circuit. Not 339 either.

Let me hope some guru here shows the way. Thanks for help.

[fzabkar]

Pin 12 is gnd or Vcc(-).

Are you sure that's not pin 11?

[najrao]

Yes, sir, I am sure. That is why I am here.

Can you give me a search method? My google fu has not helped so far.

[SeanB]

Picture of top and bottom of board would help as well.

[Ian.M]

+1.  We need good, well lit and in focus  pictures at a high enough resolution to read whatever component markings are present.

Also, post the make and model of the equipment.

[najrao]

I have tried to take a picture, but not successful. Careful wiping (with a fibre glass brush and microfibre cloth) made it even worse. My best reading earlier was " *L084CN ", but the GND does not  match up. Sorry.
Pin 11 has a 2M2 resistor attached and nothing else! I desoldered this and did measure 2M42.
This is from a Zhaoxin bench ps,  KXN6050, 60V 50A switcher.

[ArdWar]

I have tried to take a picture, but not successful.

...
Taking picture of the board surely should not be that hard right? I mean....

[najrao]

I would have thunk such board picture made no sense, so.

Still, here  goes.

Oh, my. The forum refuses my picture even after resizing.

Try and try again! The dil14 in question is nearest to the red LED.

[Greybeard]

If this is an audio amp, invest 50 cents, buy a TL084CN, replace the old one, and try at good luck!

[fzabkar]

Is C20 connected to pin #7?

[najrao]

Not an audio amp, I did say it is a bench psu.

[najrao]

No, I am afraid, Fzabkar. But you set me rolling by that question: I might have solved the mystery.

It is actually C28, not distinct in the picture. An invisible link connects it's negative pin to -wait- the IC's pin 11!. Turns out it is a negative supply, coming all the way from the service switcher well up in the picture!

So, it is almost certainly a TL084. Now to get back to decode the working of the PSU control. I may have won the rat race, but I am still a rat.

Thanks a lot.

[Greybeard]

As I said:
TL084CN, replace the old one, and try at good luck!
 

[najrao]

I have yet to establish that it is this IC that is defective in any way. I do not use the shotgun approach, there are lots more to check. Thanks for your advice.

[najrao]

Thanks to Fzabkar, I found my answer.

But there is a new problem of sanded off ic's.

Earlier, I have identified the pwm chip to be the garden variety 3525. This drives a pulse transformer but not directly; there are two dil 8 chips to boost the drive. They in turn drive the half bridge IGBT's, using isolated secondaries.

Both these txr driver chips get very hot, and load up the 12V bus. Their output side should be totem pole, but measures 56R to ground. This increases somewhat if heated. I conclude that one or both drivers is kaput.

I need to find  replacements, without knowing the ics' model number. Google offered no help.

[coromonadalix]

sg3524  or the tl494 ??
you need to check the pinout going to small transistors nearby and if theses are going into the small transformer near them


or lm324  used in the feedback circuit,  limitter   etc ...

8 pins mosfet drivers ...  many things can go there ??

[najrao]

Once again, this is the pcb of a 60V 50A (sic) CVCC bench supply, Zhaoxin KXN 6050D. China or PRC, don't know. It is received not working. The power switches are in a half bridge and are 30A 600V IGBT's; there is provision to fit and drive TWO devices in parallel, but one transistor is missing!. I plan to replace all four switches.
Because the IGBT's are fairly big, they need a hard drive, perhaps.
The PWM ic is definitely a 3525, inferred by pinout. It is good and working. The op amps are TLO84CN's, and seem to be good so far.
I am now stuck in finding out what to do about the two hot driver chips.
Thank you for your interest.

PS: Any replacement must be pin compatible!

[fzabkar]

https://www.google.com/search?q=mosfet+%22gate+driver%22+%22dip-8%22&tbs=isz%3Am%2Citp%3Aphoto&tbm=isch

I would examine the depth and shape of the cutout and dimple on the package. To me, they look like International Rectifier's style (or Microchip).

Maybe there are markings on the underside of the DIP?

[amyk]

From that picture it looks more like they tried to cover the markings with black paint as I'd expect sanding to leave a smoother finish than that. Perhaps a bit of acetone will remove the paint and reveal markings?

[najrao]

Amyk, I don't  think it is any paint. I tried 'adhesive remover' - naphtha,etc. - which did nothing.

Fzabkar, thanks a lot for the references. Yes, going by pin compatability TC4420/9  and 1/2 fit well. Must establish whether inverting or not should be the choice. Pretty much both should do, and the 6A peak 0/9 should be fine.

Using a CC supply set low at just 5.0V 200mA, I have now found that both drivers output low to start with as should. (The 3525 outputs both stay low). Driving the input of one driver turns it on into a latching state, increases the current draw to over 150mA, and control at input is lost. The other driver when driven similarly, increases the current draw slightly, but it's output stays low. I conclude that both need replacement.

May be lead-free or some shit, desoldering is a frightful PITA. I failed altogether with sucker, wick, extra rosin flux, fresh solder. Have to cut off the pins next. Don't have hot air, and must wait to get replacements to hand first before trying no-return methods.

Advice me if it is right to go for TC4420, the non-inverting.

Thanks for the hand-holding.