Daytek F19AH

[osoduro]

Re: Daytek F19AH

Hi guys I'm new in the forum ,but I do have daytek f19dh and come black scrim the green light still on and come yellow when the pc go sleep ,if I push the button on the side on-off the scrim buck on for couple of second and go dark again what could I do to make it work ? I appreciate any answers about that issue thank's

[jetadm123]

Re: Daytek F19AH

Excellent work! Glad you kept at it! Too bad about the ceramic caps. Also, we now know of at least a substitute mosfet that will work on your board. Keep up the good work.

[PlainBill]

Re: Daytek F19AH

And the result is......Daytek = Fixed....BenQ = Fixed I am back to dual monitors!!! HUGE improvement over the single IBM C51 lol

BenQ was a walk in the park because there was a previous thread on that monitor that explained the problem as well as a protection circuit. https://www.badcaps.net/forum/showthread.php?t=4304 When I get another LCD I am gonna take the BenQ down and have a stab at the protection circuit.

As for the Daytek, this has been hell and back lol. The 471k caps I ordered, I tested 4 and they all turned out to be 29nf so maybe I got a bad batch IDK but I left the current ones in there, put in the new D444's, lifted 2 solder pads in the process, and got so happy that it worked I forgot to switch out the Radio Shack caps and order Panasonics. Oh well the Daytek is done, it's working and and I'm gonna follow the whole if it ain't broke don't fix it thing for now. If anything happens to the Daytek for forgetting to change those caps I know where to look now.

I usually shut my monitors off at night but my test for them both is I am going to leave them both on for the next 2 days straight.

I have also now ordered that Repair LCD monitors book off the net and it looks like it has some GREAT info in it.

Thank you to everyone who has helped me out with this monitor especially PlainBill and jetadm123. Gonna start flippin' through that book but it's a given I will hit another snag along the way & I'll be back so until then.......

Congratulations!!! It's scant consolation, but the repairs that have you tearing your hair out are the ones that teach you the most.

PlainBill

[UserName666]

Re: Daytek F19AH

And the result is......Daytek = Fixed....BenQ = Fixed I am back to dual monitors!!! HUGE improvement over the single IBM C51 lol

BenQ was a walk in the park because there was a previous thread on that monitor that explained the problem as well as a protection circuit. https://www.badcaps.net/forum/showthread.php?t=4304 When I get another LCD I am gonna take the BenQ down and have a stab at the protection circuit.

As for the Daytek, this has been hell and back lol. The 471k caps I ordered, I tested 4 and they all turned out to be 29nf so maybe I got a bad batch IDK but I left the current ones in there, put in the new D444's, lifted 2 solder pads in the process, and got so happy that it worked I forgot to switch out the Radio Shack caps and order Panasonics. Oh well the Daytek is done, it's working and and I'm gonna follow the whole if it ain't broke don't fix it thing for now. If anything happens to the Daytek for forgetting to change those caps I know where to look now.

I usually shut my monitors off at night but my test for them both is I am going to leave them both on for the next 2 days straight.

I have also now ordered that Repair LCD monitors book off the net and it looks like it has some GREAT info in it.

Thank you to everyone who has helped me out with this monitor especially PlainBill and jetadm123. Gonna start flippin' through that book but it's a given I will hit another snag along the way & I'll be back so until then.......

[PlainBill]

Re: Daytek F19AH

I will get some of those caps along with the D444. Both those are readily available on ebay.

(Off topic)
I just cracked open a benq monitor today with no backlight.
There is actually a repair *KIT* available on ebay for this one

http://cgi.ebay.com/REPAIR-KIT-2SC57...item3355ff711b

I also found a complete service manual for the BenQ in less than 5 minutes.

If only this Daytek was that simple lol

The big problem with the Daytek occurred back in post 46 where we failed to recognize that the output resistance was too low. If we had caught the problem then this thread would have been much shorter.

As far as repairing monitors is concerned, the parts kits are the equivalent of the 'paint by number' sets. They are good for getting a working monitor PROVIDED the fault is the common failure, but they sure don't teach you much.

PlainBill

[UserName666]

Re: Daytek F19AH

I will get some of those caps along with the D444. Both those are readily available on ebay.

(Off topic)
I just cracked open a benq monitor today with no backlight.
There is actually a repair *KIT* available on ebay for this one

http://cgi.ebay.com/REPAIR-KIT-2SC57...item3355ff711b

I also found a complete service manual for the BenQ in less than 5 minutes.

If only this Daytek was that simple lol

[jetadm123]

Re: Daytek F19AH

Since the two ceramic caps are out of spec, I would go ahead and add those two to your list. 0.47nf @ 1000 volts.

[UserName666]

Re: Daytek F19AH

It would appear they are

[jetadm123]

Re: Daytek F19AH

I forgot to ask if the resistors and caps that you just tested were connected to the inverter transistors (4060AL).

[UserName666]

Re: Daytek F19AH

471k = 470pf = .47nf where "k" = +/- 10% tolerance. Your measured values seem a little low, but could be caused by the fact you're measuring them in circuit.

The resistors are OK, if the color bands are orange, orange, black.

Actually the resistors and caps were all pulled for testing.

[jetadm123]

Re: Daytek F19AH

OK I could not get anything to happen with the caps on resistance mode on both the digital and analog meter but when I put the digital to capacitor checker the one on J14 side read .34nF and the one on J15 side read .37nF.
The numbers on the caps are:
471k
1Kv

The resistor on J14 side is 33.8ohm and by J15 is 33.4ohm

Pulling the inverter transformer not surprising the dark scorch mark is on the same side as the shorted transistor.

471k = 470pf = .47nf where "k" = +/- 10% tolerance. Your measured values seem a little low, but could be caused by the fact you're measuring them in circuit.

The resistors are OK, if the color bands are orange, orange, black.

[UserName666]

Re: Daytek F19AH

OK I could not get anything to happen with the caps on resistance mode on both the digital and analog meter but when I put the digital to capacitor checker the one on J14 side read .34nF and the one on J15 side read .37nF.
The numbers on the caps are:
471k
1Kv

The resistor on J14 side is 33.8ohm and by J15 is 33.4ohm

Pulling the inverter transformer not surprising the dark scorch mark is on the same side as the shorted transistor.

[jetadm123]

Re: Daytek F19AH

Good detective work looking over the board and labels. Since the D444 was used in the earlier model and it looks to be the exact same board, it's probably the best choice as a replacement.

[PlainBill]

Re: Daytek F19AH

OK I am gonna go ahead with these D444's. I had another look at the board and the only real difference between mine and the original post other than the transistors I can see is the stickers/markings that were added to the board afterwards:

-Number stamp on filter cap (Original post 5718D - Mine 5914D)
-Number stamp on transformer (Original post L0525 - Mine L0528)
-Barcode sticker underneath the board (Original A30534134542 - Mine A30544023768)
-Sticker by inverter (Original R0194L7200 - Mine 83A000013)
-Sticker between coils

The Li Shin #'s right by the 110v in on top of the board are an *exact* character for character match.
Although the stickers previously mentioned seem to be of a little higher number on mine than in the original post which pretty much confirms my thought the F19-DH was a remake of the F19-AH so the 4060AL's were probably the newer one compared to the D444.

I'll take the readings of those resistors and ceramic caps today and pull that inverter and post some pics of it.

For caps: If the meter goes to infinite its shorted but if it rises one way (charging?) and drops the needle back (discharging?) then it is good. Am I correct on that statement?

No. If you pot the meter leads across an electrolytic cap and read very low resistance (< 5 ohms) something is shorted. If it reads infinite resistance the cap may be bad - a very small cap (< 47uF) may charge so fast you miss the reading. A normal cap will show an increasing resistance, eventually showing open. If you then switch the leads it shows a decreasing negative resistance until it discharges completely, then as it starts recharging it will show an increasing positive resistance.

PlainBill

[UserName666]

Re: Daytek F19AH

OK I am gonna go ahead with these D444's. I had another look at the board and the only real difference between mine and the original post other than the transistors I can see is the stickers/markings that were added to the board afterwards:

-Number stamp on filter cap (Original post 5718D - Mine 5914D)
-Number stamp on transformer (Original post L0525 - Mine L0528)
-Barcode sticker underneath the board (Original A30534134542 - Mine A30544023768)
-Sticker by inverter (Original R0194L7200 - Mine 83A000013)
-Sticker between coils

The Li Shin #'s right by the 110v in on top of the board are an *exact* character for character match.
Although the stickers previously mentioned seem to be of a little higher number on mine than in the original post which pretty much confirms my thought the F19-DH was a remake of the F19-AH so the 4060AL's were probably the newer one compared to the D444.

I'll take the readings of those resistors and ceramic caps today and pull that inverter and post some pics of it.

For caps: If the meter goes to infinite its shorted but if it rises one way (charging?) and drops the needle back (discharging?) then it is good. Am I correct on that statement?

[PlainBill]

Re: Daytek F19AH

Hmm OK. Umm does the D444 look suitable. I'm at a loss with all those terms on the data sheets ie: "drain source on state resistance"...Not a clue lol. I have never gone this deep into circuitry. I was just trying to match the numbers on the sheets and is seem the D444 has a few values that are a little higher.

Based on the fact that both are used on apparently identical boards, yes, it should be a good replacement. Again, I don't have any experience comparing the specs of FETs.

PlainBill

[UserName666]

Re: Daytek F19AH

Hmm OK. Umm does the D444 look suitable. I'm at a loss with all those terms on the data sheets ie: "drain source on state resistance"...Not a clue lol. I have never gone this deep into circuitry. I was just trying to match the numbers on the sheets and is seem the D444 has a few values that are a little higher.

[PlainBill]

Re: Daytek F19AH

Something else I just noticed. IDK if this means anything the datasheet for the for the 4060AL is dated March 1998 while the one for the D444 is dated June 2004 so I would guess that the D444 is the improvement over the 4060AL???

Not strictly an improvement; rather a design by another company that meets the minimum specs for the application.

PlainBill

[UserName666]

Re: Daytek F19AH

Something else I just noticed. IDK if this means anything the datasheet for the for the 4060AL is dated March 1998 while the one for the D444 is dated June 2004 so I would guess that the D444 is the improvement over the 4060AL???

[PlainBill]

Re: Daytek F19AH

After a bit of digging around I looked at the Post #1 in this thread. How I thought these to PS boards were alike it seems there is indeed a difference. The drive transistors in that pic that I can make out are:
D444
US?822

4060AL -
D444 -

Does it seem like a D444 could be suitable replacement?? If so I have readily found some on ebay and the auction says "This MOSFET transistor can be found in Xerox, Mag Innovision, and Proview LCD monitor."
http://cgi.ebay.ph/LOT-4-AOD444-N-Ch...-/200357432833

It's not unusual to have several alternate sources for components. That is good engineering practice.

PlainBill