Daytek F19AH

[UserName666]

Re: Daytek F19AH

Looks like Q13 is shorted out. As for the scorch marks, maybe the marks are caused by the heat generated by the inverter transformer? Hopefully, it's not shorted out. What do you think PlainBill?

I was thinking the same about Q13. Just for laughs and out of boredom I disconnected the bench PS and plugged the monitor PS into 110v with it all hooked up except the CCFL's and J109. Monitor functions as it should.

[PlainBill]

Re: Daytek F19AH

Looks like Q13 is shorted out. As for the scorch marks, maybe the marks are caused by the heat generated by the inverter transformer? Hopefully, it's not shorted out. What do you think PlainBill?

Q13 is definitely shorted; Q14 should also be replaced. At a minimum the inverter transformer should be pulled and examined for any evidence of overheating. It may be possible to pull Q13 and Q14 using Chip-Quik and a good soldering iron. I'm really concerned that there is a problem in the drive signal path that caused the failure.

PlainBill

[UserName666]

Re: Daytek F19AH

I got one of those SMD hot air blowers so removing it will be no problem. The problem I am having is I have already been looking for a replacement and this part is proving difficult. 0 results at digikey, findchips gives me a 14 pin IC ect.

Could you possibly tell me a little more about the "drive signal path"?

[PlainBill]

Re: Daytek F19AH

I got one of those SMD hot air blowers so removing it will be no problem. The problem I am having is I have already been looking for a replacement and this part is proving difficult. 0 results at digikey, findchips gives me a 14 pin IC ect.

Could you possibly tell me a little more about the "drive signal path"?

The actual part number is CEB4060AL, or maybe not. I'm not sure about the manufacturer. A quick search didn't bring up anything by that part number available from the usual US sources. I did a quick check for an equivalent part, but I don't know enough about FET parameters to make a good decision. Digikey has ON Semiconductor NTB18N06LT4G in stock at $1.22 each, but it has a logic level gate. They list Fairchild NDB4060 and ON Semiconductor NTB18N06 as special order items; those appear to be a better match. Again, this is outside my area of competency.

As far as the signal path, that has started looking better. By the part numbers you gave me IC1 is the inverter controller. The datasheet is here. I've marked up the drive signals; they look refreshingly similar to the datasheet. Initially I thought the path was much more convoluted. One possible explanation for the initial failure was both transistors turning on at the same time.

PlainBill

[jetadm123]

Re: Daytek F19AH

I came up with the ON semiconductor NTD6416ANT rated at 100V 17A, 81mohm. However, the rise ansd fall times are a possible issue.

Another possible solution is to dial up digikey's 1-800 number and tell them you wanted to order the Fairchild NDB4060, but that it's out of stock and if they can recommend a substitute. Other members have tried this idea with success.

Also, on the top of the board, above the inverter transformer and to the right of ceramic cap C36, are two 22 ohm 1W resistors. These seem to be sitting above or near the inverter transistors and look to be subjected to a large amount of heat. Measure their values and check to see if they're connected to the inverter transistors. Although ceramic caps rarely fail, I'm starting to wonder about C36 and C37?

[UserName666]

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

[shovenose]

Re: Daytek F19AH

since proview, mag, xerox, and daytek are probably all made y the same junk, it would probably be suitable as a replacement.

[jetadm123]

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


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

Very good observation on your part! It reinforces the reason why photos are needed, even if you've got the "same board" as the previous person.

Here's the deal: It's not unusual for the manufacturer to come up with different versions of the same board. The model number of the board could be the same, but they could have a different revision or "rev" letter. Also, a later revison like "rev B" or "rev C" usually indicates an improvement to the previous rev. So, the question is was your board produced before or after the board in post #1? If after, maybe the 4060AL mosfet was used as an improvement over the AOD444. Or is it vice versa? Or did these guys just run out of the AOD444 and substitute the 4060AL?

As for the AOD444 being used in Mag, Proview, etc. It's probably true, but those power boards were made by Mirage Electronics. Yours is made by Li-Shin.

Although the AOD444 is 12A vs 15A for the 4060AL, it may still be ok. It's usually the rise/fall times that throw people for a loop.

[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

[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

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

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

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

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

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

[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.

[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

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

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

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