Component fallen off a scope board

[mrgrateful]

Hello, this is my first post and I am rather sad. I just bought a used scope card, but the card turns out to be damaged: in the box that contained the board there was an electronic component floating around. See here the component near the spot where it belongs:

http://homes.stat.unipd.it/mgri/board_damaged_1.jpeg

It seems that someone already tried to solder it, as there is a solder blob. What component is this? Is the board seriously damaged? Is it easy to resolder it? How does it affect the board performance?

Many many thanks for any help or suggestions.

Matteo

[garyb]

that's a capacitor and it's part of a redundant system. the card may work fine without it, but it's better for it to be there. if you still have both legs on the cap, it can easily be resoldered. in the worst case, S|C can fix it.

[siriusbliss]

Best to find someone locally that can cleanup that bad solder job and put that cap back on properly.
It looks to be a power bulk cap that I would DEFINITELY solder back on!

It's part of that DSP chip's power supply. Fairly critical capacitor.

It's an easy fix for someone that has the tools.

Greg

[garyb]

that WOULD be absolutely necessary, but the system is overbbuilt. this has come up before. but yes, if someone local could clean it up, that would be best/easiest.

[siriusbliss]

that WOULD be absolutely necessary, but the system is overbbuilt. this has come up before. but yes, if someone local could clean it up, that would be best/easiest.

Better safe than sorry.
Also, those AD chips get hot, so best to do a REAL good soldering job (it's simple).

Greg

[garyb]

that WOULD be absolutely necessary, but the system is overbbuilt. this has come up before. but yes, if someone local could clean it up, that would be best/easiest.

Better safe than sorry.
Also, those AD chips get hot, so best to do a REAL good soldering job (it's simple).

Greg

yeah, but this has come forward before. Ralf(remember Ralf?) told the user to just use the card anyway. it was then explained(astroman i'm pretty sure) why there was already sufficient protection. i didn't argue publicly because you WERE giving the proper advice, i'm just letting you know that i didn't trivialize the problem on my own opinion. Creamware was not worried about the loss of one cap, although it's better with all of them. there are more caps than necessary to ensure clean power(typical germans). this happens to those cards all the time, especially when people ship used ones. the solder is probably factory, it's surface mount.

as i said, you gave him the correct advice, it's better safe than sorry.


-edit-:lol: yeah, there's an ass. i thought it was a pm well, it serves me right for ignorantly running my virtual mouth off.

[siriusbliss]

that WOULD be absolutely necessary, but the system is overbbuilt. this has come up before. but yes, if someone local could clean it up, that would be best/easiest.

Better safe than sorry.
Also, those AD chips get hot, so best to do a REAL good soldering job (it's simple).

Greg

yeah, but this has come forward before. Ralf(remember Ralf?) told the user to just use the card anyway. it was then explained(astroman i'm pretty sure) why there was already sufficient protection. i didn't argue publicly because you WERE giving the proper advice, i'm just letting you know that i didn't trivialize the problem on my own opinion. Creamware was not worried about the loss of one cap, although it's better with all of them. there are more caps than necessary to ensure clean power(typical germans). this happens to those cards all the time, especially when people ship used ones. the solder is probably factory, it's surface mount.

as i said, you gave him the correct advice, it's better safe than sorry.

Having just completed the design of a large, multi-DSP layout myself, I can't emphasize enough that the more caps the better - especially with re: to spanning current (heat) and reducing noise across the power/ground planes on the PCB.

These boards are old, and yes, I remember Ralf saying that they were 'overdesigned', but hey - it's ONE CAP. It's not like a chip flying off the board - so why not just solder it back on?

Greg

[mrgrateful]

Thanks for the advice. Knowing that the board might work even without that cap is an enormous relief.

I have some soldering experience, so I would like to solder the capacitor back on. Since the capacitor appears to me as polarized, my next problem is: which way should I solder it? I think the worst thing I can do is to solder it the wrong way round.

Also, the capacitor fallen off the board has very short legs and to solder it may be a problem: I do not know how to interpret the "05 47 6v" mark on the capacitor (I don't know too much about electronics). Can you please suggest where I could find one of these capacitors in order to replace the old one?

Again, many thanks for the help. I think this forum adds a lot of value to these boards.

Matteo

[astroman]

just look at the next DSP, there's a cap in identical position.
solder this one to the board with the same orientation - it's not critical as the 'pads' are quite large.
Afaik those buffer caps have to sit as close as possible to the power connections of the DSP, as the 'need' for juice may rise in such a small time (due to clockrate), that cable lenght really matters.
But you don't damage anything if you continue to use it - worst thing is that an instruction may fail once in a while if the chip gets under heavy load.

Just as a sidenote: the cap most likely didn't come off all by itself or bad factory soldering...
there's a clear mechanical impact at the DSP pins just where that cap is located, possibly from handling the board while setting it up in the narrow PC environment.
Sometimes the part remains in place and then one day drops.
nothing to worry tho - I have a card someone even managed to short-circuit by pluggin it in...

cheers, Tom

[eccles]

Also, the capacitor fallen off the board has very short legs and to solder it may be a problem: I do not know how to interpret the "05 47 6v" mark on the capacitor (I don't know too much about electronics). Can you please suggest where I could find one of these capacitors in order to replace the old one?

Matteo,
This is an aluminum electrolytic cap, in radial SMD format. Here's a somewhat random example: http://search.digikey.com/scripts/DkSea ... E4512TR-ND

I just did some research on the markings. 05 is manufacturer specific, and describes the size/temp/ESR ratings, which are most likely not important. "47" is 47 uf, 6v is 6 (prolly 6.3) volts. Confirm with S/C if replacing. Typical power supply buffering capacitor.

It looks like the leads on yours are intact. I would re-use it as it probably is fine.

I've had the exact same thing happen to another Scope board. It ran great without the cap, but I'd follow the advice of the others & put it back in if doable. You might be able to ascertain the polarity by looking at a close-up of an identical card, or seeing if the cap "fits" in one direction, but not the other (that's what I did but it was obvious). And you are right - if you solder it in backwards it will let out the magic smoke, prolly go boom & might take out your card.

I used just a bit of glue (don't remember, think it might have been epoxy) to hold it in place, then soldered it back in - good as new.

Also http://forum.allaboutcircuits.com/showt ... hp?t=20444 if helpful.

[siriusbliss]

If you scope probe one or the other capacitor pad against a mounting hole, or connector shield pins, you'll find which side of the cap is grounded - usually the neg. side.
Unfortunately in the somewhat infamous way, I see the usual lack of silkscreen that could help make it obvious which orientation is correct.

Greg

[dante]

Maybe try to heat sink the solder, what I do is have a metal clip or two handy, once the solder is on, clamp it with a clip to absorb heat. I have on occasion, when job is on side of board, used a small tin clamp underneath which has also got soldered - then touch with damp cooling sponge and when solder dry - cut the protruding part of tin clamp away.

[astroman]

... You might be able to ascertain the polarity by looking at a close-up of an identical card, or seeing if the cap "fits" in one direction, but not the other (that's what I did but it was obvious). ...

there's really no need to make it more complicated than it is:
the cap IS reusable
there is NO need to confirm the 6V 47microFarad as that's just what it is
sorry, it's (a Scope card and) not the kind of buffer cap mentioned above: the black stripe is upward (pointing to the edge connector)
if it seems too tricky to put this very item in place again, just get a 'regular' cap (6V 47yF), cut it's wires and solder it to the pad, (-minus) positioned upward (see above).

cheers, Tom

[mrgrateful]

Thank you.This is all invaluable advice. The leads of the fallen capacitor are very short, see here:

http://homes.stat.unipd.it/mgri/board_damaged_5.jpeg

I think I will then solder solid wire to the leads, using a soldering heat sink clip in order to protect the plastic base of the capacitor:

http://www.radioshack.com/product/index ... Id=2103242

Then, I will solder the capacitor oriented like this:

http://homes.stat.unipd.it/mgri/board_damaged_3.jpeg

I really hope this is the correct orientation, as I have no way to check looking at nearby DSP's, since, as you see, the next DSP does not have any capacitor in that position (and it's the same for all other DSP's).

However, I hadn't noticed the mechanical impact on the DSP pins (thanks astroman for pointing that out). It is very clear from this picture:

http://homes.stat.unipd.it/mgri/board_damaged_4.jpeg

Now, my question is: can I make sure the DSP is still working? I'm afraid that if it's not, reattaching the capacitor would probably just be wasted time...

How would a non-working DSP affect the overall board performance?

Thanks again for all the support and great suggestions.

Matteo

[astroman]

hi Matteo,

looks like the board has taken some fall and landed on an item with edges...
hard to imagine that this happened while removing the board from it's slot.
whatever - it's (probably) not such a big deal as it looks.

First check that there's no short circuit by one of the damaged lines
bend them back into their original position with a tiny screwdriver or knife
in case some are cut and the distance is small you can just let some solder run down the wire
(needs a small tip on the soldering iron)
if the distance seems too big, solder a small wire to the pad of the chip, bend the wire to where the connectors come out of the chip and solder the top part, then cut off the rest of the wire
after soldering use a magnifier glass and check if any solder drippled between the lines
remove it with a sharp knife by 'cutting' beteen the DSP lines

on the cap just break off the black material and bend the connectors a tiny bit inwards
this should give you enought distance for the soldering iron
double check that there are no connections to the metal case of the cap
don't worry about heat while soldering the cap - unless you try to frie it really hard...

I wouldn't expect the DSP to be broken (it's possible, but not very likely)
let's assume it is broken indeed, then it doesn't matter at all if it's the last 'regular' DSP that gets allocated for processing.
It's almost impossible to notice the difference in performance with one of 14 or 15 chips missing.
If it's the control DSP then I don't know if it's function is hard-coded to the chip.
In the worst case the board would refuse to run.

Did you install it at all or did the fallen-off part prevent you from trying ?
Imho you have a fair chance to get this running again

cheers, Tom

[Fluxpod]

Get the cap direction right.That is important.
For the bend legs on the dsp.Make sure they do not connect to any other leg.If they do you may damage the quick logic fpga.You can use a needle to slightly bend them in place.If they are cut you probably will not be able to fix em.Exept you have very good smd solder skills and propper tools-hooks and so on.
What i would do:Bend the dsp legs so they dont touch anything,use a magnifing glass.
Try the card and if it works forget about the cap.If it shows instability,solder the cap back on.

I would like to ask where you bought the card, if it isnt too much to ask.

The damage on the dsp seems to be from the cap that got hit very hard to come off.Maybe claim a case with the shipping company.

Good luck.

[mrgrateful]

Hi,

the broken cap prevented me from installing me the board at all. I guess the suggestion coming from all these comments is to first try it anyway. I will do it tomorrow, hoping I find the time.

I bought this card off Ebay last week. The guy who sold it seems in good faith when he says that the card was 100% functional when shipped. However, the package was perfect at arrival and certainly did not receive any hard hits. The board was wrapped in antistatic bags, while the cap was loose in the box, so the damage was not done during shipping. It is hard for me to believe that the previous owner didn't notice anything, but maybe that's just what happened. This also seems to point me in the direction of installing the board anyway.

I will let you know if this story has an happy ending.

Thanks,

Matteo

[garyb]

if those legs on the dsp are intact, then it probably works. if they are damaged, then it's probably best for S|C to fix it. perhaps, there is insurance from UPS? it's quite common for that type of damage to happen in transit via UPS, especially when the board is packed in a different way than when it was new. to make an insurance claim, you will need all the packing and you will need the sender to call UPS. if this was done via Paypal, they may have some protection for you as well.

[astroman]

as far as the photos tell the legs are NOT intact - at least they need bending back into the proper direction to avoid short circuiting.
It's impossible to apply that specific damage to a packaged item.
The impact is precisely punctual from an angle, for example if it fell onto a rack-ear edge.
If the cap would have been hit like Fluxpod suggests, then the right side of the cap would show traces, but it's flawless.
Aside from that a round cap can never produce a flat impact... a falling screwdriver could...
Imho it's a relatively simple mechanical damage, but a bit tricky due to it's miniature size
You could also position a piece of copperwire in place by something called 'third hand'
I wouldn't underestimate the cap, as it seems not for power buffering.

cheers, Tom

[garyb]

Imho it's a relatively simple mechanical damage, but a bit tricky due to it's miniature size

i think so too.