245BW, can't find problem. No 24 or 6.3V, standby is good.

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Yes. Non of the FETs are shorting.
U5 - 4.73K
U3 - 10K
U4 - 10K
U6 - 4.71K
Fuse F1 not blown

[selldoor]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

So have you checked out the inverter board as per toasty

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Sorry first listed Panasonic is EB (are they no good?).

[Yaaman]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Hello

I know this is old topic but I've got very similar issue with exacly the same power board and I'll need your help.
Blue led is solid, I can power on/off. I have no 5.3V and 24V.
What I've done so far:
- I recaped all electrolytic capacitors - Rubycon ZL, YXF, Panasonic FR (are they no good?) and FR and large Chemi-Con KXG (good enough?)
- I changed two shorting transistors: QM802 and QM803
- I removed yellow glue

I measured voltage on ICM801:
Pin 4 as ground
1 - 4.27V
2 - 4.27V
3 - 2.66V
5 - 5.10V
6 - 3.21V
7 - 3.21V
8 - 5.08V
9 - 14.55V
10 – 0.2V
11 - 4.98V
12 - 6.88V
13 - 0.00V
14 - 7.08V
15 - 14.98V
16 - 2.58V

ICB801S
Pin 3 as ground
1 - 24mV
2 - 16.50V
4 - 1.21V
5 - 390V

And few more:
5.3V - 0.47V
24V - 48mV
Standby – 5.29V
PSON – 3.25V

Big Cap – On – 390V Off – 330V

What would be my next step?

[Toasty]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

** UPDATE **

Inverter board was received and installed. Unit now works very nicely.

Awaiting some caps to redo the Video/Graphics board as kc8adu pointed out issues with the 225BW he has.
I investigated mine and found some widely varying ESR readings on identical caps... 'nuff said!

See Page 24 of this thread:

https://www.badcaps.net/forum/showth...t=6930&page=24

.

[Toasty]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Caps List for BN44-0195A power supply Samsung 245BW :

MAXIMUM HEIGHT = 25mm

There is sufficient room around the caps that a 12.5mm can be used where a 10mm was, or a 10mm for a 8mm, etc.

Mains (original to board) cap was not replaced. Tested good in ESR, value, leakage.

CB804 - 22 / 50
CB805 - 2.2 / 50
CB806 - 47 / 50
CB809 - 47 / 50
CB812 - 47 / 50
CB853 - 2200 / 10

CM814 - 10 / 50
CM851 - 1000 / 35
CM852 - 1000 / 35
CM855 - 470 / 35
CM857 - 1000 / 10

CP801S - 82 / 450 { ~30mm diameter, 20mm height }
CP804 - 10 / 50

13 caps

I'll get some drawings and photos up when I can.

Toast

[Toasty]

Samsung 245BW - No 24v or 5.3v - standby is good

**UPDATE**

I have received this unit (purchased) from epicelite.

I recapped the PSU to my specs for caps using HE, FM, FC series'. It eliminates questions down the road. Since there has never been a list made of the originals I was unsure of what was in place when I got this unit.

I did some Googling and came up with:
http://www.ccl-la.com/blog/index.php...4-lcd-monitor/

It is not the same monitor { 2493HM }, but it is the same PSU, BN44-00195A. A list of caps is provided, but the page is done as a graphic so the list and repairs can't be copied (easily). { Hello PaintShop camera mode! }

{ Elektrotanya skips right over this model number in it's BN44- series listing. }

After recapping, a bench test showed the supply in correct working order as PlainBill had noted when he had it and tested it. BTW: It's 5.3v, not 6.3v as the thread title indicates.

Reassembled the unit and the symptoms remain. Went to check the inverter and saw no 24v available. The meter would flicker occasionally on pressing the power button, but no significant reading, except that -something- was happening.

Disconnected the interconnect cable to the Graphics board. Cycled the power and 24v came right up and stayed on the Graphics board connector.

Shut the unit down and started probing the inverter board with the ohmmeter.
Found both lower FETs shorted on the board. One D-S, the other G-S.
An ohms test of the 3 transformers show them to be a match.

Both FETS are from Anpec and listed as Enhancement Mode types.
APM4030A - N Channel
APM4050A - P Channel

Not available anywhere in the US, but Anpec's site shows them as in current production.
A suitable replacement could likely be found by datasheet-to-datasheet comparison, but I became bleary-eyed after the 6th sheet and went browsing.

Found a salvaged inverter for cheap from a different model monitor { LS24HUBCFL }, but again, the board is the correct number, BN44-00163B.

I figure that either I will get a working inverter or at the least the 2 FETs I need to finish this one.

The question remains: What caused the FETs to blow in the first place?
Both inverter onboard caps test good in ESR, value, leakage.
The fuse is intact and the board shows no darkening from overheating.



Toast

[PlainBill]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

The 450v 82uf capacitor has failed on this model,what i have noticed when it fails is a severe flickering of the back lights,But I wonder if it could cause other problems?
Just something to think about.

On this particular supply, I don't think that is the issue. It seems unlikely I could overload both outputs and have it work perfectly if the mains filter cap were bad.

PlainBill

[alexanna]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

The 450v 82uf capacitor has failed on this model,what i have noticed when it fails is a severe flickering of the back lights,But I wonder if it could cause other problems?
Just something to think about.

[PlainBill]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Any progress?

Nothing definitive. I've received the power supply and tested it.

When I used a 2.2K resistor from S_B to PSON to turn the main supply on, it came right up. The power supply is rated at 5.3 volts at 3 amps and 24 volts at 3 amps. I tried various loads, ranging from about 1 amp on each output to over 4 amps on both outputs, and it worked perfectly.

The only conclusion I can come to is there is a short on one of the loads (signal board or inverter), which prevents the main power supply from coming up. I haven't tried shorting either output to see if that is a valid conclusion.

The only obvious problem at this point is a number of the caps had been replaced with NTE caps. A complete recapping would be required before I'd try using it in a monitor.

I did get voltage readings on the main SMPS controller at various loads, and frankly don't understand exactly what they mean.

PlainBill

[Toasty]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Any progress?

[epicelite]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

What if I sent you the power supply board? Or at least all the boards, dunno if you could figure the thing out without the LCD screen and backlight.

Shipping the whole thing would be like $25 and I'm too poor/cheap for that.

[PlainBill]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

So what's next then?

Should I redo those readings from that IC?

Yes, please. After that, you have several options. Zulururu has a replacement IC on order, until he has received installed it there is no point in your duplicating the effort. If you wish to replace CM512, equivalent parts are Digikey P12114-ND, Panasonic ECW-F6123JL or DigiKey 495-3215-ND, Epcos B32672L1123J000. Each would cost under $1.00, shipping would run under $3.00 by USPS First Class Mail. And I will admit, I don't know if that will work.

I've said this before, troubleshooting this supply presents serious problems. Most SMPS supplies operate in the 70 Khz range; this one runs at 1 Mhz. I seriously doubt any DMM can react to the drive signal. On the other hand, an oscilloscope can easily see the drive signals.

PlainBill

[epicelite]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

So what's next then?

Should I redo those readings from that IC?

[PlainBill]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Ugh can't find my camera.

It says

1 2 n J 630V
384 MMK(II or possibly an H?)

Thanks for the effort. You have confirmed that it is a 12 nanofarad 5% 630 volt cap.

PlainBill

[epicelite]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Ugh can't find my camera.

It says

1 2 n J 630V
384 MMK(II or possibly an H?)

[PlainBill]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Dunno.

Can't read them too well:
12 U J 630V

This is my meter, nothing special.

http://www.harborfreight.com/7-funct...01B2163195C&mr

Any chance you can get a sharp picture of the numbers on the cap?

PlainBill

[epicelite]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

I have another meter but no leads for it.

[Toasty]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

That meter does not have capacitance testing ability. (I have one of them.)

[epicelite]

Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

Dunno.

Can't read them too well:
12 U J 630V

This is my meter, nothing special.

http://www.harborfreight.com/7-funct...01B2163195C&mr