Bad DAC-19M00B PSU, would appreciate some pro-tips

[ankan]

Hi BadCaps Forum!

I've gotten interested in learning electronics lately and a few weeks ago I got 2 broken LCD screen that I thought would be good to start to troubleshoot/try to fix.

Before I get started I want to say that I've read all the threads I see when I search for DAC-19M008 here on Badcaps.
There was a bunch of useful information there, and I have come to the conclusion that most likely one of the AOP605 mosfets is fried,
but since I can't seem to find any replacement parts where I live, I wanted to double check so that it's as I suspect before ordering the parts from abroad.

So, here we go.

The monitor is a ACER 1916w. The first thing I checked was if the LCD was still functional, this mostly because I was thinking to make this screen into a diy projector,
but I realized that the panel is to big and also I could use a secondary screen and 19' would be perfect. So using a flashlight I can see that the LCD panel is still Ok, and shows the graphic it is suppose.

So I decided to open the monitor up and see if there was some loose cable to the back light or some easy fix like that. But no go.

What I did after this was to google it, which lead me here. And after reading all I could in you forums I will now post yet another ”help my dac-19m008 is busted” (BF Rev-1A).

In the picture ””DAC-19M00B-BF-01A-TOP”” you will see the different values I got when I checked the voltage on the caps (just after unplugging power) I also checked the fuses and the mosfets.

And if I understand what I read here on the forum, the problem seems to be the first AOP605 mosfet on IC201,
it's the only mosfet giving me a low resistance response (~1-2 ohm using my multimeter set to 200ohm)
The other 3 is not giving me any value on the multimeter, and as I understand when the mosfet malfunctions it's common that it shorts and gives a low resistance reading.

DAC-19M00B-BF-01A-TOP.jpg

(All the images are also attached in this post)

Schematic.jpg


Symbol - Reading - Info from manual (M = Measure?)
C200 - 0v - ALMINUM CAP, 25v 220uF M 8*11,5
CE101 - +18v - ALMINUM CAP, 25v 220uF M 8*11,5
CE102 - +18v - ALMINUM CAP, 25v 1KuF M 10*20 TP5
CE103 - +18v - ALMINUM CAP, 25v 1KuF M 10*20 TP5
CE104 - 0v - ALMINUM CAP, 10v 1000uF M 10*16 TP5
CE105 - 0v - ALMINUM CAP, 10v 2.2mF M 13*20 TP5
CE108 - 0v - ALMINUM CAP, 25v 330uF M 8*16
CE109 - 0v - ALMINUM CAP, 25v 220uF M 8*11,5



These are done with my multimeter set to 200 Ohm

IC201 AOP605
S1-G1 2 Ohm
S1-D1 0,5 Ohm
G1-D1 2 Ohm
S2-G2 ---
S2-D2 ---
D2-G2 ---

IC202 AOP605
S1-G1 ---
S1-D1 ---
G1-D1 ---
S2-G2 ---
S2-D2 ---
D2-G2 ---


My conclusion after this is that mosfet 1 on IC201 should be dead right?
The F200 fuse is also blown, but this I understand is quite common with mosfet malfunction (or maybe the other way around?)

What makes me a bit confused though is what I should do with the caps, are they busted,
or do I get these readings because the blown F200 fuse and the faulty mosfet, or should I just go ahead and replace them all just for the sake of it?

I've also attached 2 pictures of the caps in profile, and they look pretty ok, but then again I'm a rookie in this subject

DAC-19M00B-BF-01A-SIDE1.JPG


DAC-19M00B-BF-01A-SIDE2.JPG


Please let me know if there is something else I should check, or if there is something I've done completely backwards

Have a good one!

[stj]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

you have it working other than the lights.
so you have 2 options.

1: remove the fets, controller chip, ce101 & c200 and fit an led kit for about $20

2: replace ic's201,202 and caps c200 and ce101 with panasonic FR series and hope the transformer & tubes are good.
it's 50/50 unfortunatly.

personally i'd get the led kit every time now they are so cheap.

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Oh, I forgot to mention that the manual is also attached in the post.

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

you have it working other than the lights.
so you have 2 options.

1: remove the fets, controller chip, ce101 & c200 and fit an led kit for about $20

2: replace ic's201,202 and caps c200 and ce101 with panasonic FR series and hope the transformer & tubes are good.
it's 50/50 unfortunatly.

personally i'd get the led kit every time now they are so cheap.

Hi, thanks for a very fast reply

Yes, 20 bucks to get it working again is a bargain, I just wanted to make sure I order all the parts I need (hopefully) and also get some more knowledge of what's the cause, and whats the cure

[stj]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

well i looked at the manual now,
those caps i mentioned look like the tops are domed - can you confirm that?

as for the fets,
desolder them & meter them again.

the problem with metering transistors or fets that connect to a transformer is you can tell if the meter is seeing the fet or the transformer.
and the upper chip has a lot of heat marks around it

[bammbammfran]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Your caps are shots. especially the 3 220x25.
the 2 100x25 tend to go too
That is probably why your are getting 18 volts instead of 14-15v
and it may be why the f200 fuse is out
And it's also the reason you P605s overheated. I have seen them get hotter than that and still work
change the caps and fuse and give it a shot

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

well i looked at the manual now,
those caps i mentioned look like the tops are domed - can you confirm that?

as for the fets,
desolder them & meter them again.

the problem with metering transistors or fets that connect to a transformer is you can tell if the meter is seeing the fet or the transformer.
and the upper chip has a lot of heat marks around it

The C200 And CE 101 is indeed domed (as well as ce109)



You point of metering things in line made sense, so I also desoldered the mosfets and checked them, the IC201 (the one with the burns around it) Still tests the same. But the other one (IC202) gave me some difference.

IC201 AOP605 (results with 200Ohm, also tested 200k without success)
S1-G1 2 Ohm
S1-D1 0,5 Ohm
G1-D1 2 Ohm
S2-G2 ---
S2-D2 ---
D2-G2 ---

IC202 AOP605 (200k)
S1-G1 ---
S1-D1 ---
G1-D1 ---
S2-G2 ---
S2-D2 40-68 k?-ohm
D2-G2 ---

I have no idea why the results we're so inconsistent, maybe my multimeter needs a new battery or maybe there is some proper explanation for it?

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Your caps are shots. especially the 3 220x25.
the 2 100x25 tend to go too
That is probably why your are getting 18 volts instead of 14-15v
and it may be why the f200 fuse is out
And it's also the reason you P605s overheated. I have seen them get hotter than that and still work
change the caps and fuse and give it a shot

It actually seems to make perfect sense, those are the 3 that are domed (see my post from a few minutes ago). So you think there might be a chance that the mosfet is still alive? Even with a almost 0 ohm resistance on the chip with the burns around it (IC201)?

I'm completely fresh when it comes to buying components like these, but I got a tip to buy panasonic FR caps from stj, is there some fuse that is preferable as well? (even though one would think that a fuse should be pretty straight forward)

[Davi.p]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Hi, i'm not a pro but i want to give you some suggestions anyway, you must change at least CE101 CE102 CE103 CE109 C200 F200 IC201 IC202 to hope that monitor come back to work, keep Ic202 in a drawer, if it will fail in future this can be a prompt replacement 'cause it can be ok. You must also check voltage with Power plug in at pin 9,10 of output connector, if you don't have 5v, check F102, if is broken replace CE104 CE105 CE108. Other good brands for el.caps are Nichicon and Rubycon, them must be low esr/low impedance...

[stj]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

i would replace both mosfets,
in my experience with invertors,
even working mosfets often have failed internal diodes and wont last much longer.
better to put a new pair in.

[stj]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

has your meter got a diode-test btw?

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Hi, i'm not a pro but i want to give you some suggestions anyway, you must change at least CE101 CE102 CE103 CE109 C200 F200 IC201 IC202 to hope that monitor come back to work, keep Ic202 in a drawer, if it will fail in future this can be a prompt replacement 'cause it can be ok. You must also check voltage with Power plug in at pin 9,10 of output connector, if you don't have 5v, check F102, if is broken replace CE104 CE105 CE108. Other good brands for el.caps are Nichicon and Rubycon, them must be low esr/low impedance...

Hey, haha, you're pro enough for me
I will plug it in tomorrow and check it, I checked F102 now and it seems to be ok, but I will check the voltage tomorrow. Thanks a bunch!

[stj]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

datasheet

[Davi.p]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Thanks for the schematic, i don't knew there was schematics for a single board! It's an interesting one, i will try to understand what the second opto does (don't mind if you don't know whats an opto)...

[Davi.p]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Its curious how the swollen caps C200 Ce101 CE109 have the same size, are in different branchs of circuit and it is not relative to proxmity to heatsinks, maybe the smaller ones due to size dries easier and get higher esr maybe because it's heat is generated outside by diodes and not inside...

[Davi.p]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

You can change AOP605 with AOP604, AP4511GD.

[bammbammfran]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

It actually seems to make perfect sense, those are the 3 that are domed (see my post from a few minutes ago). So you think there might be a chance that the mosfet is still alive? Even with a almost 0 ohm resistance on the chip with the burns around it (IC201)?

I'm completely fresh when it comes to buying components like these, but I got a tip to buy panasonic FR caps from stj, is there some fuse that is preferable as well? (even though one would think that a fuse should be pretty straight forward)

Sorry, I missed the note with the readings on the IC201 p605.
Yes, you will have to change that too besides the caps and the fuse.
You will probably have to hit ebay for the aop605
you might be able to find the rest locally ??

[stj]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

you can probably use apm4546j
i'v got some of those i pulled from LG stuff while fitting led kits.
they look compatable on the datasheets.

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

Hi, i'm not a pro but i want to give you some suggestions anyway, you must change at least CE101 CE102 CE103 CE109 C200 F200 IC201 IC202 to hope that monitor come back to work, keep Ic202 in a drawer, if it will fail in future this can be a prompt replacement 'cause it can be ok. You must also check voltage with Power plug in at pin 9,10 of output connector, if you don't have 5v, check F102, if is broken replace CE104 CE105 CE108. Other good brands for el.caps are Nichicon and Rubycon, them must be low esr/low impedance...

Sorry for a very slow answer, been a crazy busy week.

Pin 9 and 10 has +5v on them (when powered) so it seems ok. And the Fuse is ok as well.

[ankan]

Re: Bad DAC-19M00B PSU, would appreciate some pro-tips

has your meter got a diode-test btw?

Yes, it got some "combo-mode" with diode-test and a speaker symbol
(I guess it's just indicating that it makes noise when it connects?)