IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

S (Source) pins are connected to the primary circuit ground which is the Ground ref point.
BD 5.8V: This is normal.
ENUV (pin 4) .5V: There is problem here at this pin, minimum is 1V for the IC to be enable.
" I heard a sound and was slighlty startled. The screen came on when i put the meter between D and ENUV" That because the meter connections cause pin 4 to go high enough for the IC to get out off shutdown mode.
Please check the resistance between the ENUV pin 4 and S pin to see if it shows low resistance.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

S (Source) pins are connected to the primary circuit ground which is the Ground ref point.
BD 5.8V: This is normal.
ENUV .5V: There is problem here at this pin, minimum is 1V for the IC to be enable.
Please check the resistance between the ENUV pin and S pin to see if it shows low resistance.

ENUV is about 2.8 Mohms Is this low? But eh... its negative? I have found the magical negative resistor? lol

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

ENUV is about 2.8 Mohms Is this low? But eh... its negative? I have found the magical negative resistor? lol

When the power is off, its about 2k

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

"When the power is off" do mean the TV is not plugged into the outlet, right? it must not be connected to the outlet.
"its about 2k" That is low, there is a jumper wire J7080 connected to PIN 4 of the IC, un-solder one end so you can lift one end off the board, then take the reading again to see if the resistance will go up..

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

"When the power is off" do mean the TV is not plugged into the outlet, right? it must not be connected to the outlet.
"its about 2k" That is low, there is a jumper wire J7080 connected to PIN 4 of the IC, un-solder one end so you can lift one end off the board, then take the reading again to see if the resistance will go up..

Yup i mean when it is not connected to the outlet.

I dont see a J7080, Closest to pin 4 is J7026? They are the same?

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

OK, that is not the same DPS-286 as shown by the OP, I use this picture from shopjimmy:
http://www.shopjimmy.com/sharp-rdenc...upply-unit.htm
http://www.shopjimmy.com/media/catal...jqz-bottom.jpg

Which board do you have?
OK, you have the 226 not 286.

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

BTW: I dont see a J7080, Closest to pin 4 is J7026? They are the same? yes, per you board, lift one end off the board.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

Yea, its a variation board i think.. mine is DPS-226AP-1 RDENCA340WJQZ

From what i see in the other board picture? I assume you are just trying to isolate pin4? I will just go ahead with J7026.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

BTW: I dont see a J7080, Closest to pin 4 is J7026? They are the same? yes, per you board, lift one end off the board.

2.6 M ohms

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

OK, we need to trace where the other end of that jumper is connected to. I need better pictures of the STBY section so I can easily see the traces, I believe it is connected to the Cathode of Zener diode D7905? and the opto-isolator (IC7905?). I believe either the Zener or the Opto is damaged when the IC went out. You can put the jumper back in place and lift one leg of the D7905 to see if the resistance will go up.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

OK, we need to trace where the other end of that jumper is connected to. I need better pictures of the STBY section so I can easily see the traces, I believe it is connected to the Cathode of Zener diode D7905? and the opto-isolator (IC7905?). I believe either the Zener or the Opto is damaged when the IC went out. You can put the jumper back in place and lift one leg of the D7905 to see if the resistance will go up.

Here you are. Yes D7905, i think it connects to IC7906 though.

How do i test the opto? I dont have a power source to test the output.

What i have though after taking out one leg of D7905, forward resistance is 2.6m, backward resistance if i reverse the polarity is 12m.

tested D7905 seems working.

other side of opto resistance is about 1k whichever polarity. If i test the opto as two diodes on each side they seem to be working. Not shorted on the input and output sides.

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

So did you put the jumper back in place then measure the resistance with one leg of the diode lifted off the board to see if you still get 2K reading on pin 4 and S (GND)? We are trying to find out where that 2K reading is coming from.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

So did you put the jumper back in place then measure the resistance with one leg of the diode lifted off the board to see if you still get 2K reading on pin 4 and S (GND)? We are trying to find out where that 2K reading is coming from.

Ahhh... ok i get it. thanks thanks. Yes, i did take out the diode

I took out the opto. so i tested the opto by itself. not working now it seems. i guess it was the TNY264 which i was testing.

The 2Mohms and 12 Mohms were coming from the TNY264.

Ill get the opto changed and try testing again

Thanks!

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

Hey Budm

I put the a new opto, but it seems it just reverts to as if the old opto was there. Unless of course the new opto doesnt work, I tried to test it, but i am not sure how to do it. One way resistance 6M, the other side is open.


Resistance across S and EUNV goes back to about 2k ohms again.

HMmm...

Should i try changing the zener diode?

Would it be easy to just bypass the whole standby thing? i am happy to live without it.

Where should the 1v come from anyway? I tried to trace it. It ends at the zener/ opto area unless i go to the other areas..

C7918 and C7915 comes to 2V

Thanks alot mate...this is a very grueling exercise..

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

The Zener can be left out for testing for now. So with the opto removed, you do not get 2K reading, is that correct?
Did some one work on this board before?
The other board has resistors which are connected in series to provide voltage to pin 4 (you can see that in the IC spec sheet), they are R7913, 7916, 7917, 7920.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

Nope i think i still got the 2k without the opto. Do not have the board now. Will try later. I believe it came from the TNY264pn?

And nope dont think anyone worked on this as well before. When i saw the 4 empty slots where the resistors where, i was quite purplexed as well.

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

So when you removed the jumper, pin 4 shows high resistance, so the low resistance is on another end of the jumper which is connected to the opto, zener,amd I cannot see what else, you need to find out.
How abut those resistors that are connected to pin 4? They are not installed from the factory?
As you can see the intenal of the IC, pin 4 EN/UV is connected to MOSFETs inside which should not have 2K reading.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

So when you removed the jumper, pin 4 shows high resistance, so the low resistance is on another end of the jumper which is connected to the opto, zener,amd I cannot see what else, you need to find out.
How abut those resistors that are connected to pin 4? They are not installed from the factory?
As you can see the intenal of the IC, pin 4 EN/UV is connected to MOSFETs inside which should not have 2K reading.

Yups they are not installed from factory.

It seems to be coming from the zener. It works but the low resistance is from there. what specifications do you recommend? the data sheet only sorts of write a TL431. a normal 1N4728 will do?

[budm]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

Not TL431, you can leave out the Zener for now to find out if the circuit will startup or not.

[steinless]

Re: IC Number on DPS-286 AP/RDENCA336WJQZ Sharp power board

Not TL431, you can leave out the Zener for now to find out if the circuit will startup or not.

IT...LIT UP..... THANKS BUDM!!!!

Have found these specifications for the zener though. will a general 15 V zener diode do?


Can i do without the zener? if it can light up, i suppose it is more for circuit protection and at most it will fry the opto or 264 should another surge occur?

THANKS!!!!!!