Re: Transistor replacement for L240AS-00
Thanks! While it was nice having all my equipment working without issue, I'd forgotten how much I enjoy making these kind of repairs.
At work we've been trying to use thin clients wherever possible. In the places that do need an actual PC (due to special I/O, GPU requirements, etc.), we've been getting mini towers instead of the little SFF jobs. Of course, in the most recent batch (I think they're Optixplex 3040s), the regular ATX sized PSU cutout has an adapter in it so that one of these dopey long skinny SFF...
etnietering
Badcaps Veteran
Last Activity: 12-24-2022, 01:11 PM
Joined: 04-16-2009
Location: Indiana
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Re: Transistor replacement for L240AS-00
The next replacements were the 3 caps in the feedback/control part of the primary side, in the center of the board. Here we have:
22uF 50V Ltec
470uF 35V TAICON
1uF 450V TAICON
I didn't write down the series for any of these, I'm afraid. Here they are:
And removed:
The replacements are:
22uF 50V Panasonic EB
470uF 35V UCC KYB
1uF 450V Panasonic NHG
Here are the new ones lined up with the originals:
And...Leave a comment:
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Re: Transistor replacement for L240AS-00
And here we have the primary side reassembled.
Next I replaced the 8 secondary side bulk caps. The originals were:
3.3V: 1500uF 6.3V TAICON HD
5V: 2200uF 10V Ltec LZG -> coil -> 1200uF 10V TAICON HD
12V: 2x 1200uF 16V TAICON HD
5VSB: 3300uF 10V Ltec LZG -> coil -> 1000uF 10V Ltec LZG
-12V: 220uF 25V Ltec LZG
The 3.3V rail only has 1 cap because it's derived from the filtered 5V rail with a MOSFET. This provides very clean power without much filtering....Leave a comment:
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Re: Transistor replacement for L240AS-00
My company has a few dozen Optiplex 790s with these L240AS-00 power supplies. 6 or 8 of the PSUs have croaked over the last year or two. Always the same - the PC just turns off, and won't power back on. I've snagged a couple before they could be junked, and have fixed two.
The two I've fixed exhibited the same symptoms as mentioned above - blown fuse. Upon disassembly, I've found that Q100 is failed short and the primary bulk cap reads very low (2uF or lower).
Unfortunately the IPP60R199CP transistor is marked...Leave a comment:
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Re: Dell Precision 380
Sorry to revive this old thread, but I have a similar story of a Precision 390 that I had to swap some caps on.
I have an old Precision 390 that I got pretty cheap as part of a corporate auction. It's a pretty decent machine, Core 2 Duo E6600, 4GB of ECC DDR2, etc. I have it set up on my mess of a workbench down in the basement, where I mostly use it for datasheet lookups, quick calculations, etc. It also takes part in primegrid challenges, and serves as the VNC client for a headless machine that also takes part in the aforementioned primegrid...Leave a comment:
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Re: Need a replacement power supply with -5VDC
It might be easier to just add your own -5v rail to a power supply you already have.
Something like the [URL="http://www.onsemi.com/pub_link/Collateral/MC34063A-D.PDF"]MC34063[/URL] could be used to take some of that excess +5v and invert it to -5v. Only takes a handful of extra parts, and the datasheet has all the equations you need to figure out all the component values.
Alternatively, if the board just needs -5v present to POST, and not for anything else, you could take a PSU with a -12v rail...Leave a comment:
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Re: "Polymer" capacitor ID question
You appear to be correct. Thank you very much! I should bookmark that website...
And I guess they're real polymers, too.Leave a comment:
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"Polymer" capacitor ID question
Hey everybody, long time no post!
My current project is to build myself a new storage server, since my old one is nearly full. The case I ordered comes with 3 SATA backplanes, each of which can connect to 4 disks. Each backplane has a total of 10 capacitors on it (one for each drive +12v, one for each drive +5v, and one for each voltage at the power connectors). The caps are all sleeveless, ventless cans with blue writing that says:
728
330
16
I figure they're all 330uF @ 16v, and the lack of a vent leads me to think that they're polymer,... -
Re: Help designing car buck boost for amp.
Oh sorry, I'd started my reply before you made that edit. I've never actually used the external transistor circuit, 1.5A has always been enough for me. From the schematics, it looks like there's already a darlington configuration inside the chip, and the external transistor just adds an extra stage to it. By putting a darlington outside, you'd be effectively making a 4-stage darlington. I don't see why it wouldn't work, maybe get a few of each and test things out.
7b needs a tapped inductor, so if it were me I'd go with ...Leave a comment:
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Re: Help designing car buck boost for amp.
Sure thing. You're correct, in general you do want to keep things close together. Shorter traces have lower resistance (and therefore the circuit is more efficient and stays cooler), and less parasitic inductance and capacitance. Neither of these should be a problem though. When I'm designing a circuit board for a power supply, I use a ground plane on the bottom for all of the ground connections. This keeps the ground resistance very low and can act as a heatsink. All the rest of the traces go on top. This also can make it easier to route...Leave a comment:
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Re: Help designing car buck boost for amp.
You might want to look into the M33063: [url]https://cdn.badcaps-static.com/pdfs/6b78adf19eef3709c93704d54f50c1cb.pdf[/url]
Output voltage up to 40V. I've used them in several projects to kick 5v up to 12v to run a PC fan. It's only good for 1.5A though, but if you look at page 7 of the datasheet, there's a way to use external switch transistors to increase this current.
I can give you more info on the project I've used them for if you'd like, just let me know! Good luck!Re: Help designing car buck boost for amp.
Leave a comment:
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Re: ThermalTake PurePower 520W recap
Sorry to revive such an old thread, but I have an update on this PSU. I replaced it... I got a new videocard for Christmas (GTX 460), which draws a bit more power than my old 8800GTS, and under heavy load the computer would just shut down. I don't know if it was the OCP (I don't know where the levels were set/what was on each rail), or the over temp shutting things down (it would take a few minutes after the load increase for it to shut down, and the air coming out the back was pretty hot).
So the update - all the caps I replaced...Leave a comment:
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Re: AT power supply to replace power adapters
You shouldn't run into any problems. Just make sure to load both the 12v and 5v rails to keep the voltages in check. If all your devices are one or the other, get a dummy resistor and some thermal tape and attach the resistor to the inside of the power supply case. I've done this and can give you more info/pictures if you'd like.
Good luck!Leave a comment:
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Re: Power resistors in transistor-like packages
The dummy load I built uses a few of them: [url]https://www.badcaps.net/forum/showthread.php?t=8870[/url] (about halfway down). I used them for that exact reason - they're very easy to mount to a heatsink.Re: Power resistors in transistor-li...to a heatsink.Re: Power resistors in transistor-like packages
TheLeave a comment:
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Re: replace primary capacitor in antec psu
My brother's antec had a bloated panasonic primary cap. Probably because the fan's don't run very fast. They were only 85C rated, so I replaced them with 105C ones.Leave a comment:
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Re: word 2007
Wow! Thanks for all the tips guys! If only I'd asked you a few years ago when I was having that problem...I try to stay out of that lab as much as possible now, and use open office writer in the other lab or at home. No office 2k7 crap will ever touch my computer.Leave a comment:
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Re: word 2007
Well I don't have a solution (I try to stay away from Word as much as possible), but I do have a similar rant...
So I'm in the lab (at school), typing up a lab report or something, and after every hard return Word decides to put in an extra line break. Not a real one though, because you can't delete it, just a blank line to separate the paragraphs. It took me the better part of the afternoon to figure out how to shut that "feature" off. It's not in options, or preferences or anything. I don't even remember where it is. It would have taken less...Leave a comment:
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Re: Bridge rectifier vs four diodes
Usually you can estimate based on the size (i.e. small = low current, big = high current). You can also look at the numbers on them (which may require unsoldering them from the board) and try to find a datasheet.Leave a comment:
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Re: What is your testing PSU and what's its story?
Mine's a 330W Logisys advertised as 480W, which I've upgraded to maybe actually be able to put out 330W. The whole saga is detailed [URL="https://www.badcaps.net/forum/showthread.php?t=7193"]here.[/URL]Re: What is your testing PSU and what's its story?
Mine's a 330W Logisys advertised as 480W, which I've upgraded to maybe actually be able to put out 330W. The whole saga is detailed [URL="https://www.badcaps.net/forum/showthread.php?t=7193"]here.[/URL]Leave a comment:
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Re: the gutless, bloated, and fried power supply hall of shame
On Digikey, look under "Common Mode Chokes" in the "Filters" category. There's a couple thousand to choose from.
For the Y capacitors, search for "Y1" or "Y2", and then look in the Ceramic or Film Capacitor categories. Most important thing to worry about here is the lead spacing too.Leave a comment:
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