Does this look like a cracked solder joint to you?

asktoby · Post by **asktoby** » Mon Oct 03, 2022 2:19 am

I've been having bad stability issues with my card, no audio, loud crackles, etc.
I took a look at all the capacitors under a microscope to look for any damage and it all looked fine apart from this one hair-line shown here.
https://docs.google.com/presentation/d/ ... sp=sharing

Does this look like a failed solder joint to you?

astroman · Post by **astroman** » Mon Oct 03, 2022 4:09 am

Nice photos, but unfortunately meaningless: with these caps the real solder joint sits below the cap and is invisible.
During production the heated solder simply floats the pad on the circuit board and only the peripheral part of that pad is visible.
ps: that‘s not entirely correct because the 2 connectors of the cap may extend over the visible part of the pad, so consider this just as an illustration of the idea.
Possibly a cap may be misplaced slightly and the solder connection isn‘t very solid then.

astroman · Post by **astroman** » Fri Oct 07, 2022 1:05 pm

Sorry, I should have noticed it earlier... but the cap between the 2 rightmost DSPs has fallen off

(check the bottom on your motherboard)

asktoby · Post by **asktoby** » Sat Oct 08, 2022 6:15 am

O.M.G. How did I not spot that - thank you for pointing it out!

I couldn't find the cap anywhere, so I'll need to buy a spare.
Is anyone able to confirm if these would be a good replacement?

The part I need

What I'm suggesting I buy
https://www.ebay.co.uk/itm/125548587839 ... media=COPY

nebelfuerst · Post by **nebelfuerst** » Sat Oct 08, 2022 7:19 am

I think these should do.

If you want to "optimise" further, you could check for the lowest ESR capacitors.
But the design of the pulsar/scope doesn't require this. Even the loss of a cap shouldn't be a problem.
If all caps are degraded to < 5us, this might become an issue.
Cap degradation goes with temperature, so having fresh air directly blown to the pulsar/scope is a good idea.

asktoby · Post by **asktoby** » Thu Oct 13, 2022 2:33 am

OK, fun times. Now that I know what to look for I've noticed that I'm actually missing FOUR capacitors!

I've updated the graphic here to highlight them:

https://docs.google.com/presentation/d/ ... sp=sharing

I'm borrowing a hot-air rework tool and have ordered some leaded solder paste, I'm going to have a go at fixing this poor battle-worn card.
I'm thinking I'll replace all the capacitors while I'm there for good measure.

I need to know which capacitors go in the spaces marked A, B, C, D in the image linked above. Is anyone able to tell me please?

Also I need to know their polarity.

astroman · Post by **astroman** » Thu Oct 13, 2022 7:31 am

Did you compare with photos of the io-plate if there are really caps missing ?
On circuit boards there are frequently empty pads that have been supposed as cap location, but later in the design process were given up. Some pads look like there‘s never been anything attached to it.

asktoby · Post by **asktoby** » Thu Oct 13, 2022 10:54 am

Good point. I looked online and could only find two photos of the ADAT I/O Plate so have added them to my linked document:
https://docs.google.com/presentation/d/ ... sp=sharing

It looks like there were maybe two revisions of the ADAT IO plate, and I have the one with fewer capacitors on it. So yes, I only have one capacitor missing from my Pulsar card. Hopefully someone who knows for sure can weigh in to confirm if this is correct.

astroman · Post by **astroman** » Thu Oct 13, 2022 1:15 pm

It is safe to assume there never have been parts on these pads: there‘s absolutely no trace and you would have found them when removing the io-plate (they can‘t escape from under the mounted circuit board).

asktoby · Post by **asktoby** » Thu Oct 13, 2022 10:07 pm

You underestimate how many times I’ve reseated the IO Plate to try and fix scope issues!

astroman · Post by **astroman** » Fri Oct 14, 2022 5:42 am

OK...

but whenever a part breaks off a solder pad, there WILL be a kind of „connector footprint“, just like on the pads between the 2 rightmost DSPs. It‘s inevitable, no exceptions.
In case there was an error during assembly, the board would have arrived DOA, death on arrival.

asktoby · Post by **asktoby** » Mon Nov 07, 2022 8:26 am

OK, let's do this
https://imgur.com/a/oCduAgg

Post by **garyb** » Mon Nov 07, 2022 8:39 am

a regular iron for surface mount? yeeeks!

i am sure that it can be done, if it's just a cap...

asktoby · Post by **asktoby** » Tue Nov 08, 2022 4:50 am

It's going well!
I've replaced all the 47uF 16V and 47uF 6.3V caps on both Pulsar IIs.
I do have a hot air rework tool here also, but I'm finding it easier with the regular iron to be honest.
I'm now looking at the I/O board to see which caps I need to order to replace on that.
If you could take a look at slide 3 here and confirm that I've correctly identified the parameters of the caps that would be really helpful:
https://docs.google.com/presentation/d/ ... sp=sharing

Post by **garyb** » Tue Nov 08, 2022 7:50 am

looks ok. the proof is in the pudding...

asktoby · Post by **asktoby** » Fri Jan 27, 2023 1:56 am

I'm back to report that the re-cap was successful!

I made a video of the process here:

"Sonic Core Creamware Pulsar II capacitor replacement"
https://youtu.be/5dcZLVWpHcw

dante · Post by **dante** » Sat Jan 28, 2023 11:52 am

Wow ! Well made video - nicely done.

PlanetZ forums - scopeusers.com

Does this look like a cracked solder joint to you?

Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?

Re: Does this look like a cracked solder joint to you?