Re: BN44-00195A strikes back!
I removed the power mosfet and still got ~390v,so
I replaced the DMM battery with a brand new one, and now my readings look much more accurate...
I'm actually getting ~300V on the big cap and ~15V on the 24V line.
The ON/OFF shows 5.19V now.
The PFC isn't working so I guess the IC is bad.
I'm going to replace this, ones again,but what I would to know is if there's any way to force the PFC to work,without the IC.
steven10
Member
Last Activity: 12-27-2015, 02:52 PM
Joined: 10-17-2015
Location: Italy
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Re: BN44-00195A strikes back!
the logic board is definetly good.
I'm also able to navigate trough the menu...brightness was set to 100, so I tought reducing the brightness could at least cause the bulbs to flash, but I was wrong
Last edited by steven10; 12-22-2015, 05:31 PM.Leave a comment:
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Re: BN44-00195A strikes back!
I didn't check the inverter board yet,I just took some measurements on the connector pins using chassis as ground, for now.
+24V(x5)=~21V
GND(x5)=0V
SOS=7.20V
ON/OFF=6.15V
A_DIM=3.10V
EX_PWM=3.80V
Backlights remain always off,but i've noticed that [B]I can see images if I put a torch against the screen
[/B]Re: BN44-00195A strikes back!
I didn't check the inverter board yet,I just took some measurements on the connector pins using chassis as ground, for now.
Last edited by steven10; 12-22-2015, 09:41 AM.Leave a comment:
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Re: BN44-00195A strikes back!
I'm also reading 0V on both windings of the LP801 transformer
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Re: BN44-00195A strikes back!
how it's supposed to be working with those readings?
Readings on pins 4 and 7, indicate that the mosfet is open
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Re: BN44-00195A strikes back!
Yes, I did that but I replaced the zener ones again and took some measurements.
PFC IC FAN7530
Pin1=~2.10V
Pin2=0.06V
Pin3=0.02V
Pin4=0V
Pin5=~0.2V
Pin6=GND
Pin7=0V
Pin8=17V
Big cap = ~390V both with power ON and OFF.
That's pretty strange cos the PFC circuit is not working at all but I have 390V(fluctuating) on the big cap.
Only the VCC changes with power OFF(from 17V to 0V), all the other reading stay the same...
So maybe there's...Last edited by steven10; 12-19-2015, 11:31 AM.Leave a comment:
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Re: BN44-00195A strikes back!
OK,I was expecting the VCC to be around 16V.
But i'm reading 2.45V between GND and INV pin of the PFC IC(The FAN7530 doesn't work if there's less than 0.45V on the INV pin) so I don't know why it's not working.Leave a comment:
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Re: BN44-00195A strikes back!
Don't you think 19V is to high as VCC?
And Why i'm getting an output of 20V when power is ON and 0.00V when power is OFF if the PFC circuit isn't working(always 350V on the big Cap both whit power ON/OFF)?
350V seems to much too, becouse the voltage between the legs of the big cap should be around 320V when power is OFF and than 380V when power is ON...Leave a comment:
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Re: BN44-00195A strikes back!
I'm getting steady19V VCC (pin 8) and 0.00V on pin 7(pin out)Leave a comment:
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Re: BN44-00195A strikes back!
I'm getting ~350V on the big cap both with power on and offLeave a comment:
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Re: BN44-00195A strikes back!
Shipping time takes to long, so I ended up going to a "local" store, 2 days and the parts were there
Parts replaced and still black screen but i'm now getting 20.5/22.7V(fluctuating) on the 24V line(before was 0.00V ).
Any suggestion?
PS: Reading taken with everything plugged inLast edited by steven10; 12-18-2015, 10:45 AM.Leave a comment:
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Re: BN44-00195A strikes back!
Ok,tested the MOSFET with a 9 volt battery and it is good(probably my DMM doesn't have enought power to turn this MOSFET ON).
Put it back and read 0.67V on pin 7(PFC output pin).
Checking for low resistance readings on the IC, I got :
1)6K7
2)5K8
3)1M1
4)1R
5)5K8
6)GND
7)5K5
8)170R
Pins 1,3,4 and 6 seems good.
Pins 2,5,7 seems bad.
By removing the jumper that drives the VCC to the SMPS IC, I'm able to read correct 7K4 on pin 8 of the PFC...Last edited by steven10; 12-03-2015, 12:28 PM.Leave a comment:
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Re: BN44-00195A strikes back!
How can i test di PFC IC?
Can i put a working 600V 7A mosfet just to check if I'll get the boosted voltage?Last edited by steven10; 11-28-2015, 08:34 AM.Leave a comment:
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Re: BN44-00195A strikes back!
I've pulled off QP801s and it seems bad.
The source-drain diode is fine but I'm not able to turn it on the "On state"...
When I charge the gate capacitance, I got no readings between drain and source(open circuit).
Before pulling off QP801s I was getting 15.9V on the Vcc line, so the PFC IC was getting what it needs to run.
The 19.5V on the QB802 collector seems to be low and I don't know why the voltage getting higher when power is off.
maybe something related to the bad QP801s mosfet?Last edited by steven10; 11-24-2015, 01:33 PM.Leave a comment:
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Re: BN44-00195A strikes back!
I replaced QB802 with a 2sd2394 60V 3A NPN transistor.
didn't found a 15V zener ,but I just replaced it with a 10v zener in series with a 5.1V one.
These were the reading BEFORE changing those parts:
Power ON/OFF:
A = 17.9V/15.7V
B = 11.7V/9.7V
These are the reading AFTER changing the parts:
Power ON/OFF
A = 19.5V/22.5V
B = 15.9V/0.0V
The voltage between the big cap almost remained the same,now it fluctuates from 310V to 325V(305V to 310V...Leave a comment:
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Re: BN44-00195A strikes back!
I found a 2sd2394 (TO-220F package)NPN 60V 3A transistor from a scrapped power supply board,it should be fine.
Tommorrow I'll check for zener,it's over midnight here
...
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Re: BN44-00195A strikes back!
Of course I mean QB801(QB802 on the diagram) not QM801... my mistake
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Re: BN44-00195A strikes back!
QM801 is bad!
I just removed it from the board and it has a short between B and E...Last edited by steven10; 11-21-2015, 02:00 PM.Leave a comment:
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Re: BN44-00195A strikes back!
These are the readings:
17.9V between A and GND REF
11.7V between B and GND REF
While looking very close to the smd side of the board(thanks to your picture),i've noticed that DZB805 had a tiny little crack on top of the package,just a gentle touch with a sharp screwdriver caused the package to break.
Now there's a "huge" hole on this,i'm going to test it but i think it's 99% bad.
I also noticed that QM801 shows a very low resistance between Emitter and Base, don't know if this depends...Last edited by steven10; 11-21-2015, 08:41 AM.Leave a comment:
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Re: BN44-00195A strikes back!
ICP801s (FAN7530)Leave a comment:
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