Dell W1700 LCD Rev00

[schnipke]

Re: Dell W1700 LCD Rev00

I got my monitor to finally work a few weeks ago. I replaced the caps with those beefy radio shack ones and I got some SMD fuses online from the littelfuse website for free. They gave me eight fuses to try. I replaced both fuses even though one appeared to still be good and it worked.

Hopefully this can help others with the turning on then off problem. Replace both caps and fuses even if they look OK. Also, you can get the SMD fuses free online from the companies website. Takes a good two weeks to get to you though.

-Schnipke

[PedroDaGr8]

Re: Dell W1700 LCD Rev00

I got my monitor to finally work a few weeks ago. I replaced the caps with those beefy radio shack ones and I got some SMD fuses online from the littelfuse website for free. They gave me eight fuses to try. I replaced both fuses even though one appeared to still be good and it worked.

Hopefully this can help others with the turning on then off problem. Replace both caps and fuses even if they look OK. Also, you can get the SMD fuses free online from the companies website. Takes a good two weeks to get to you though.

-Schnipke

exactly which model are they?

[artie67]

Re: Dell W1700 LCD Rev00

Thanks to all the info above I replaced the resistors and caps with the aid of a pro(soldering). I bought six pairs, therefore have enough for two other repairs. Caps are 105 degrees, and the resistors are from socal fuse (littlefuse) as per postings. I'll sent along sets for anyone for $10 incl shipping. Thanks again to all in the forum.

[He's Dead Jim]

Re: Dell W1700 LCD Rev00

hello all, i would like to thank everyone for the information in this thread. it helped me fix one of the two problems that i have with this monitor (w1700).

problem one was the screen going black for a second or two at a time for a few months until it finally went black completely.

i replaced the caps and fuses on the inverter board, but the display only powered up for a second and then shut off. i figured that i screwed something up, so i ordered a new inverter board. when i installed it, the same problem still existed, so i know that my work was good. the new board will go into another monitor that was missing a board.

so now the problem remains. i turn the monitor on, the green light comes on and it shuts right down. maybe there is a safety circuit that is being tripped, i'm not sure yet.

another thing that i did was instead of just turning the monitor on, i held the button in. the monitor stayed on, but it came up white with the word composite in the upper corner. i did not want to leave it on for too long, but the video from my pc did not show up on the monitor.

i am waiting on a schematic, but if anyone has a copy they could email me or a possible solution, please respond in kind...

thanks.

[davetech]

Re: Dell W1700 LCD Rev00

I got my monitor to finally work a few weeks ago. I replaced the caps with those beefy radio shack ones and I got some SMD fuses online from the littelfuse website for free. They gave me eight fuses to try. I replaced both fuses even though one appeared to still be good and it worked.

Hopefully this can help others with the turning on then off problem. Replace both caps and fuses even if they look OK. Also, you can get the SMD fuses free online from the companies website. Takes a good two weeks to get to you though.

-Schnipke

schnipke
what is the part# from radio shack for the caps?

i bought mine from mouser
Xicon low ESR Radial Electrolytic,
25v 220uf 105c.

i really don't see why my board repair failed but i have to keep trying.


he's dead jim,
i didn't know that there was a schematic for it. can you post or send me a copy? i should be able to get it with that.

i have had a few emails from people wanting to get their board fixed, i can't do it until i know all of the issues with the boards. some repairs work and some are hit and miss. hopefully if i try the RS caps and all is well, it would be that the inverter board is fickeled.
let's hope.



dave

[cstradling24]

Re: Dell W1700 LCD Rev00

I went to my local shops and they did not have the exact caps but he did give me a normal fuse, not SMD. It was a pico fuse so I went ahead and removed the old SMD fuse, put two leads in then my new fuse on the leads. Put it all back together and believe it or not it has been working now for a few months without a problem. Again, I did not replace the caps, just put a random fuse that an electronics specialist gave me

[wacker]

Re: Dell W1700 LCD Rev00

SUCCESSFUL REPAIR!!!!!

Parts required:

2 -- 220uF/35V electrolytic caps (RS part # 272-1029)

2 -- Littelfuse 2 Amp SMD fuses (part # 429 002)

Take great care in installing the fuses. . .they're very, very small and require a bit of skill in applying just enough heat to flow the solder properly.

Be sure to do a continuity test after installing fuses to verify proper installation.

Of course, observe correct polarity on the caps.

The 35V caps are a bit more robust than the stock 25V units. Physically, they are slightly larger, but it's not a problem.

Total cost: <$6.00

irie,
--cap'n bob

I know the polarity on the caps but which is - + on the board??

[johnstof]

Re: Dell W1700 LCD Rev00

Hello everyone. I hope this thread is still alive because I tried the fix but it did not fix my monitor.

Prior to repair, and thanks to this thread, I found that both of the fuses were blown. The caps seemed fine but I replaced both of them and both of the fuses. Confident that my nice monitor would work perfectly again following this 1 hour, $5 repair job, I put it all back together.

Alas, I powered up and still no picture. I have a green light on my power button and audio as I did before the repair.

I opened the monitor back up and both fuses are blown again. I checked and verified that both caps were installed correctly and the solder joints were not touching eachother.

I am hopeful that someone out there can point me to a possible cause and fix.

Thanks,
John

[starfury1]

Re: Dell W1700 LCD Rev00

well no idea on the circuit and no photo to look at so I am guessing.
You got blown fuses and they blew again so guess
you got a short circuit
Most probably a transistor or fet has gone short and perhaps Zener diodes as well

could be more then one device

Inverter PCB seem to be the bain of LCD TFT's and HV transformers are a known failure as well with inverters

So there is a few things you are going to have to check

Dont fix em so don't know the most likely suspects with that PCB you have
but the above are always good starting points

This may possibly have happen cause of bad caps
but the point is now,
its more then bad caps that is your issue by the sounds of it.

Have a look through these 2 threads, might give you some ideas

https://www.badcaps.net/forum/showthread.php?t=4304

https://www.badcaps.net/forum/showthread.php?t=1303

HTH Cheers and Welcome

[Krankshaft]

Re: Dell W1700 LCD Rev00

Most likely if your inverter is made by Benq one or more of the 4 driver transistors next to the high voltage output transformers is probably shorted.

Check them out if you have them with the diode function of your DMM.

Its usually a bad idea to just replace a fuse without checking for other failed components because in most cases it will just blow again.

[johnstof]

Re: Dell W1700 LCD Rev00

Krankshaft,

Thanks for the suggestion. There are some photos of the board on this thread. Could you possibly point out the 4 driver transistors for me or at least describe their location on the board?

FYI, I did not blindly replace the fuses without knowing what was wrong. I replaced the fuses and the caps as described by this thread since it seemed to be a common problem and was the fix for several people. But now that the fuses re-blew I need to take a deeper look into the cause.

Regards,
John

[davetech]

Re: Dell W1700 LCD Rev00

they are the 4 8-pinned ic's near the caps





i have been looking for those specific driver via the marking on the chips. i have had no luck. if i had a diagram of the ic, i could find the right sub for it.
so this is where i am stuck. if someone has a source that could match the markings on the ic, it would help .

thanks to everyone who has had input.


dave

[Krankshaft]

Re: Dell W1700 LCD Rev00

Oh I was under the impression that this was a monitor .

This TV doesn't use driver transistors for the inverter.

What makes you suspect that the inverter is the cause and where are the fuses you replaced?

The only thing I would check on the inverter board is if the transformers have shorted turns other then that if the backlight works and you replaced the caps move on.

Your problem is probably on the power board I assume that the fuses you replaced are on that board and what that fuse supplies is current for the inverter.

[davmax]

Re: Dell W1700 LCD Rev00

Having read through thread I suspect that transistor failure is a real possibility.

The transistors that fail are usually those that drive the inverter transformers, those two large components with an obvious wire winding.

To identify the transistors requires an ohmmeter set for continuity/diode check. With this setting place one probe on one of the transformer connections ( on the side nearest to the centre of the board) with the other lead probe the obvious transistors first (three legged SMD devices) above the 8 pin chips. If the meter registers continuity (a short) you have found a transistor that is connected to the transformer. With the transistor located use both meter probes to check to see if there is a short between the three transistor terminals, if there is a short you have found the failed transistor or its mate. They are in pairs a short in one with be reflected in the other. Both will need replacing.

If the three terminal transistors are not connected to the transformer check out the four 8 pin chips, they may be transistor packages.
The challenge is. What made the transistors blow? Are there shorted turns in the transformers? Maybe. This requires much more sophisticated testing.
Sometimes simply replacing the transistors will fix the problem. If failure continues the cause must be found.

I see that fuses were bridged. This is not a good practice. Greater damage can occur. Use the correctly rated fuses. If advice is required please ask.

Usually best to get an expertly fixed board. However not all fixers have identified the cause of failure and the fix will not last long. See my thread on the BenqQ7T3 and the hidden cause of failure discovered towards the end of the fix story. https://www.badcaps.net/forum/showthread.php?t=4304

I have the same problem as many of you have described. I can turn the TV on and it will show a picture for about a second and then the picture just goes black. The light stays green but no picture. The sound also works fine. I went ahead and took out the backlight inverter but I dont know exactly what needs to be replaced. I also dont know where to buy the replacement parts either. Here is a picture of the board.



Is it the big green caps in the center of the board?

One more thing, where are the fuses that should be checked.

The weird thing to me is that some of you that replaced the caps ended up with the screen coming on and then off again which is the problem I have.

[davmax]

Re: Dell W1700 LCD Rev00

Just to improve my last post please substitute "Multimeter" for "ohmmeter"

[davmax]

Re: Dell W1700 LCD Rev00

That is an interesting input. What is used instead of transistors to switch the inverter transformers?

[davetech]

Re: Dell W1700 LCD Rev00

That is an interesting input. What is used instead of transistors to switch the inverter transformers?

transistors are used. but the IC type instead of the norm.
the 4 8-pinned ic's are Q80 Q81, Q40, and Q41.
the manufacture is an "A" with the circle around it .like "@" only captial.
the markings are
@ 4600
BD313K

i believe that this is the problem. i have searched the interweb to no avail for the description #. if i could find the manu. with that @ symbol, it would help a lot.


dave

[Krankshaft]

Re: Dell W1700 LCD Rev00

I hope you've learned your lesson NEVER buy a Dell .

While I admit I love the freebies and the free LCDs I'm getting from people I know how frustrating it must be when a relatively new product craps out on them just when the warranty expires.

Anyhow back on topic I had the same problem yesterday when I wanted to check out some ICs on an inverter. There was nothing wrong with it but I was curious about the ICs.

Most likely that IC if you can't find data for it is a proprietary part manufactured specifically for the inverter manufacturer and it isn't publicly available.

Without a datasheet you can't check the IC because you are just probing blind.

The best solution if you suspect this IC is to replace the inverter board.

Here is a site that sells it:

http://www.lcdpart.com/Products/t50104500mss.html

This is NOT an OEM replacement it is a Third Party replacement part for this model.

However it will plug and and screw in just like the original.

[leogetz2007]

Re: Dell W1700 LCD Rev00

Thanks to all for the help. I went and followed the instructions step by step. I went the easy route and bought the board for $80 at lcdparts.com. Ordered it Friday (before 3 p.m.) was in my mailbox Monday! I am left now with an inverter board that I am willing to sell for $15. The board has the usual busted (bulging) cap and what appears to be busted fuses. I must mention that when taking the unit apart, I might have dislodged one of the connectors. Since I did not want to take a chance replacing capacitors, fuses, then have to worry about the connector, I decided to get the replacement. I don't know where my ohmmeter is even if I still have it, and just did not have the patience to look around for the replacement connector. Anyone interested, just leave a reply here or email at leogutierrez@usa.com. Thanks again for all your replies here and I hope someone can make good use of my old board.

[Krankshaft]

Re: Dell W1700 LCD Rev00

Glad we could help.

The best option if you don't have the knowledge to do a repair is to replace the inverter board assembly.

However in my case with LCD monitors the inverter and the power board are one so that forced me to learn how to troubleshoot them.