Dell PowerConnect 2716 Switch PSU; low voltage

[evilkitty]

I have 2 of these, one working, the other not so much
I know the large 100uf, 400v cap is good
i did test the 47uf startup cap, it did barely pass, but maybe i forgot to read the unit on the multimeter
i assume the capacitance will degrade over time so i probably should replace it, and i assume a EEU-FR1E471Y will be fine, but it is still within spec so the issue should be else where right? I have read this cap is a common cause of failure in these

my issue is i am getting 0.7v output, before testing those 2 caps i think i was getting 0.5v
none of the caps are showing any bulging or leaking
i attached a picture of the power supply i found with a google search

what part should i check next

[sam_sam_sam]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

You need to find the switching power supply IC chip on this board it is going to be any where from 4 to 8 terminal to it google the part number it could even be s surface mount IC chip ones you found that chip look for a capacitor near that chip replace it first before you do anything else

Please post a photo of the bottom of this power supply board
Thanks

Some things to check the main board fuse also look for blown apart part or burn up parts and where they are on the board

If fails to turn on the power supply then I change that chip
Then if still does not want to work then we go from there

I hope this helps

I have had my own nightmare with an Ault 3.0 volt @ 5 amps power supply that was hit with a lighting surge

Power supply one

I found one open resistor that had a “0” ohm on surface mount chip also the optic sensor was blown apart and just the pin were there replace that and the power supply would power ON and OFF and just keep doing it

On power supply two

It had blown the main fuse on the board and did figure out why
So I put in a box I will work on it later

So I decided today to remove the switching IC chip from board # 2 and see what happens on board # 1 ( the optic sensor chip might be toasted on this board as well I am going to order some parts for both of these boards

Well it did not go well it shot sparks out of the bottom of that chip but it did not blow the fuse on the power supply board that because I use a electronic fast acting fuse controller I built a long time ago it was set to .025 amps

It has a range of .025 amp to about 6 to 7 amps and very quick to respond to over current

I have had to repair this electronic fuse controller a few times in the past because things did not go so well on the device that I was working on

I use it all the time on switching power supply so I know when one dose not work right

[budm]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

i did test the 47uf startup cap, it did barely pass, but maybe i forgot to read the unit on the multimeter
i assume the capacitance will degrade over time so i probably should replace it,"
So you did not test the ESR of the cap? You should replace it anyway, needed or not so you do not have to deal with it in the future.
The primary section has been cooking for awhile as you can see the board is turning brown from the heat.
Caps and diodes in the cold side tested fine for sure?

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

i did test the 47uf startup cap, it did barely pass, but maybe i forgot to read the unit on the multimeter
i assume the capacitance will degrade over time so i probably should replace it,"
So you did not test the ESR of the cap? You should replace it anyway, needed or not so you do not have to deal with it in the future.
The primary section has been cooking for awhile as you can see the board is turning brown from the heat.
Caps and diodes tested fine for sure?

I tested the capacitance, it was i think -18% ish, from what i saw all Electrolytic have a 20% tolerance, does that +/-10% or +/- 20%?
So if i use a working garbage cap i am going to replace from my other board do you think it may get it to put out 5v? obviously not intend to leave it in there, just to see if that cap is the issue

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Well the garbage cap worked, i just stuck it on a 1" lead made from Ethernet wire to the left over solder from removing the failed cap on the bottom of the board
it lasted over a year and a half doing the same thing, so why not another 15 seconds?
well it puts out 5v and it is able to power the switch up

The stock 47uf cap tested at 39.27uf, my scrap one tested at 50uf

[Stefan Payne]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

The stock 47uf cap tested at 39.27uf

wich still seems fine.
Especially for high voltage caps the capacitance is on the lower side.
Even for japanese ones...

[budm]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

I tested the capacitance, it was i think -18% ish, from what i saw all Electrolytic have a 20% tolerance, does that +/-10% or +/- 20%?
So if i use a working garbage cap i am going to replace from my other board do you think it may get it to put out 5v? obviously not intend to leave it in there, just to see if that cap is the issue

When you check the cap, you need to check ESR also not just capacitance. That 47uF more likely to have high ESR.

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

How can i test ESR?
i have 2 multi meters to work with
craftsman 82008 - http://www.sears.com/craftsman-cm-cr...p-03482008000P
southwire 21050t - http://www.southwiretools.com/tools/tools/21050T

[budm]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

You need cap meter that can also test ESR, not the typical meter that you have.
Just go to EBAY, for example:
https://www.ebay.com/sch/i.html?_fro...meter&_sacat=0
You can get meter that can do ESR, CAPACITANCE, and it can also test Transistor and DIODE, ETC.

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

so are these any good?
https://www.ebay.com/itm/122612092649
i saw a bunch that look like this some testing parts, looks like you just slap a part in there and press a button and the part is magically detected and you get a schematic and specs on it

[Per Hansson]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Any of the ESR meters in my quote here is good, the one you linked is very old and not really recommended...

Yes of course, it was just to show the lowest price possible.
If you are really interested in an ESR meter here are a couple nice ones:

https://www.ebay.com/itm/GM328-Trans...Y/152443029396

https://www.ebay.com/itm/2016-EZM328...a/182344211065

https://www.ebay.com/itm/BSIDE-ESR02...r/162714576281

I have the same switch, first had to change the startup cap:
https://www.badcaps.net/forum/showpo...&postcount=232

Then a few years later I had to change them all, so if you need cap details they should be all there
https://www.badcaps.net/forum/showthread.php?t=53745

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

thanks, found a GM328 from a us seller for less
https://www.ebay.com/itm/132268934443

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Tester just arrived
This is the not working start up cap
35.85uf
vLoss 17%
ESR 40 Ohm

i take it that is pretty bad given a new Nichicon 10uf cap is 10.75uf; 0.8% vloss;1.4Ohm ESR
PN: UKL1H100KDDANATD

[sam_sam_sam]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Tester just arrived
This is the not working start up cap
35.85uf
vLoss 17%
ESR 40 Ohm

i take it that is pretty bad given a new Nichicon 10uf cap is 10.75uf; 0.8% vloss;1.4Ohm ESR
PN: UKL1H100KDDANATD

That ESR reading means that it has gone high which means that it is ( bad )

A new one would read about .350 to about 1.something

[budm]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Tester just arrived
This is the not working start up cap
35.85uf
vLoss 17%
ESR 40 Ohm

i take it that is pretty bad given a new Nichicon 10uf cap is 10.75uf; 0.8% vloss;1.4Ohm ESR
PN: UKL1H100KDDANATD

As expected.
BTW always fully discharge the cap before making the measurement or you will blow up your new meter.

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

As expected.
BTW always fully discharge the cap before making the measurement or you will blow up your new meter.

Will a cap passively discharge over time and if so how fast (eg sitting in a cardboard box)?

I have a shot 470uf cap from here
My multimeter shows this cap as 0.11 nf
But this new meter shows me this
Capacitance: 194.3uf
vloss: 12%
ESR: 8.1 Ohm

on the other my multimeter shows this cap as 0.1 nf
But this new meter shows me this
Capacitance: 437.9uf
vloss: 2.5%
ESR: 0.34 Ohm

this cap appears to be in better in much shape than the other, but my multimeter does not see the difference in the Capacitance
why is this?

[budm]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Will a cap passively discharge over time and if so how fast (eg sitting in a cardboard box)?

I have a shot 470uf cap from here
My multimeter shows this cap as 0.11 nf
But this new meter shows me this
Capacitance: 194.3uf
vloss: 12%
ESR: 8.1 Ohm

on the other my multimeter shows this cap as 0.1 nf
But this new meter shows me this
Capacitance: 437.9uf
vloss: 2.5%
ESR: 0.34 Ohm

this cap appears to be in better in much shape than the other, but my multimeter does not see the difference in the Capacitance
why is this?

Did you remove the cap and test it OFF the board?
And do you have any new 470uF (or any other values) around to test?

It will self discharge due to leakage resistance (very high resistance but it may hold the charge a long time, best to use appropriate Value and Wattage resistor to discharge the cap and then test it with Volt meter.
This is one of many good website for learning:
http://www.electronicdesign.com/anal...e-stuff-anyhow

[evilkitty]

Re: Dell PowerConnect 2716 Switch PSU; low voltage

Did you remove the cap and test it OFF the board?
And do you have any new 470uF (or any other values) around to test?

all test were done out of board, board is waiting on good caps to be ordered
the bad 47 uf caps acts as you would expect and so does my 10uf cap