Dell 3008wfp faulty power supply

[fuus]

Re: Dell 3008wfp faulty power supply

OK, so, it seems like my diode has died again. The other diodes in the group read 5 Volts across (or similar) and the D22 reads 0

EDIT: just one thing to add, the diode I used was a STPS40170CT. That is right, right?!

I'll attach some pictures of the current situation. I do still have 2 spare diodes if you guys would advise soldering in another diode!

I havn't incuded pictures of the front due to it being identical to pictures previously posted: https://www.badcaps.net/forum/attach...0&d=1331994994
https://www.badcaps.net/forum/attach...1&d=1332371819
https://www.badcaps.net/forum/attach...1&d=1332371819

Thanks, Fuus

[selldoor]

Re: Dell 3008wfp faulty power supply

EDIT: just one thing to add, the diode I used was a STPS40170CT. That is right, right?!

Yes that appears to be correct-others have used 60's- I dont know this board but you will need to check if the original diode was insulated (electrically) from the heatsink and if it was then the replacement should be.

Did you test the new diode before you put it in.

What does it test like now

I havn't included pictures of the front due to it being identical to pictures previously posted:

Our looking at other people's boards will not help repair yours.

[fuus]

Re: Dell 3008wfp faulty power supply

Yes that appears to be correct-others have used 60's- I dont know this board but you will need to check if the original diode was insulated (electrically) from the heatsink and if it was then the replacement should be.

The diode qas indeed insulated by two plastic o rings, which were put back exactly as found.

Did you test the new diode before you put it in.

What does it test like now

I didn't test it before putting it in, however when it was in it had the same reading as the other diodes (around 5V)

Our looking at other people's boards will not help repair yours.

Ok, I will upload a picture of the front first thing tomorrow morning, but I assure you it's identical to those other pictures.

Thank you for the help selldoor, it's much appreciated

[Lumberjack777]

Re: Dell 3008wfp faulty power supply

Hey fuus. I think I may have found the problem by looking at your pictures. First of all; are you using a quality rosin core solder for electronics? Because your solder joints appear to be dull and dark grey-brown. They should be shiny. That's part of it. But I think I saw a solder bridge right above where it says C41. It appears that SMD resistor and the 3 lead component (the diode?) have a solder bridge. They should have a gap between those components. I believe this may turn out to be a soldering issue. I have been there many times. Good luck! L-J-7

[selldoor]

Re: Dell 3008wfp faulty power supply

I was looking at that - may be just the pic or flux. Fuus perhaps you can clean it up a bit and take another pic.
There are a few joints that look a bit dodgy but again it may just be the picture. Can you look at C44 same pic as above right hand side - it looks burnt?

[Lumberjack777]

Re: Dell 3008wfp faulty power supply

I was looking at that - may be just the pic or flux. Fuus perhaps you can clean it up a bit and take another pic.
There are a few joints that look a bit dodgy but again it may just be the picture. Can you look at C44 same pic as above right hand side - it looks burnt?

Yeah. I think the reason it keeps burning out is now due to a soldering problem. The best pics I saw of the bridge were the ones Fuus uploaded in post #94. Take a look at pics #1 and #3. They show a shiny bridge from the smd resistor to the 3 leads. There HAS to be a gap there, or it will short. I hope I wasn't butting in here Selldoor. Thanks for helping him. *thumbs up* L-J-7

[selldoor]

Re: Dell 3008wfp faulty power supply

@lj7 - not a problem - more the merrier.

[fuus]

Re: Dell 3008wfp faulty power supply

Sure enough, the short was there. I couldn't capture it on camera, however it was deffinatly there..

I have attached pictures of the soldering iron I used (A Weller SP40L), could you recommend a better tip to use? The one currently in the iron isn't quite the right size so heat transfer is terrible.
I also attached a picture of the solder I used, which is some bog standard stuff?

Thanks again for the help guys!

[budm]

Re: Dell 3008wfp faulty power supply

Just FYI: I use Weller 2.5~3mm wide tip, but the main key about the soldering iron is the wattage, I do not use anything less than 40watts, 60 Watts with wide tip is good for removing components off the board.

[fuus]

Re: Dell 3008wfp faulty power supply

this soldering iron is a 40W model. Could you link me to the tip you have? And would it fit other weller soldering irons? When I use the bigger tip (which for some reason doesn't tin?!) heat transfer is no problem and it was very easy to unsolder. The smaller tip however has a thinner barrel and thus the surface area for heat transfer from barrel to tip is not large enough. Or alteast this is my theory..

[fuus]

Re: Dell 3008wfp faulty power supply

bumpy

[selldoor]

Re: Dell 3008wfp faulty power supply

Hi as you have asked a specific question you will need to wait til budm gets back or is there still problems with the PS - you gave the impression that repairing the short fixed it?

Soldering with a 40w iron - unsoldering is helped if you heat the joint dry then add a little new solder which will help the old solder to melt. If it is
a big joint or a big component or there is a heatsink nearby, preheating the whole area with a hairdrier or gently with a heatgun can make it a lot easier as the heat from the iron is not conducted away as quickly.

[fuus]

Re: Dell 3008wfp faulty power supply

thanks for the reply selldoor, I just want pushing in the direction of a correct end for me soldering iron to use for this project, as my current tips arn't working well.

Thanks, Fuus

[selldoor]

Re: Dell 3008wfp faulty power supply

I have been looking on CPC for tips for your iron but they only seem to be 6mm. They also have soldering irons and this one
http://cpc.farnell.com/duratool/d018...?Ntt=sd0112787
Is almost as cheap as the bits. Perhaps you can find them on ebay or a shop
near you may stock Duratool near where you live.

[fuus]

Re: Dell 3008wfp faulty power supply

When I asked at local shops about soldering irons, the only things they ever stocked (rare) was unbranded 25W irons..

May try bodging it with Tin Foil in gaps

[Lumberjack777]

Re: Dell 3008wfp faulty power supply

When I asked at local shops about soldering irons, the only things they ever stocked (rare) was unbranded 25W irons..

May try bodging it with Tin Foil in gaps

Hey Fuss. Weller is a very popular soldering iron. You can check at hardware stores, hobby shops, or electronics shops. Or you could try online stores or eBay like Selldoor mentioned. I'd get a nice copper tip. Fairly pointed for precision soldering.
I have a cheapo $15 - 40 watt - no name brand I got off eBay from some arts and crafts store. It has a pointed tip and has served me very well. But I keep it well tinned. And use a slightly damp sponge to keep the tip clean and tinned. Then I always tin it just before I turn it off.
I think one of the unspoken heroes of soldering is flux. I got a syringe with flux with my Chipquik kit and I use that flux all the time. I dab a little on leads before unsoldering and that desoldering braid just sucks it up like a vacuum cleaner. I also use it for motherboard through hole desoldering. I think the proper use of flux has increased my soldering skills by about 50%. It also creates very solid and shiny soldering connections.
Good luck! L-J-7

[fuus]

Re: Dell 3008wfp faulty power supply

I have literally checked 20 stores in the local area, none of which stock decent soldering kit
I suspect I will have to go on an eBay trawl.. I do already own a tin of flux and a stand with sponge, so should be fine on that front!

Thanks again, Fuus

[fuus]

Re: Dell 3008wfp faulty power supply

SO: It looks like I've blown a different transistor (the one behind D22). Any ideas what model it is?

EDIT: The diode is labelled D9 if that helps anyone?

Also, I fixed my soldering iron! Whoopee! All it took was some sanding on the tip to remove the oxidisation and it was new one again!

[selldoor]

Re: Dell 3008wfp faulty power supply

Looks like you are going to have to extract the D9 and see if there is a part number on it

[fuus]

Re: Dell 3008wfp faulty power supply

Result: here we have a STPS30L60CT