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S.F. Bay Area - SMT rework help?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author S.F. Bay Area - SMT rework help?
Dave Peck
Hi All,

I have a digital polysynth with a bad DAC chip that needs to be replaced. But it is a very teeny tiny 20-pin TSSOP package SMT chip with very small 0.025" pitch on the solder leads. It's a Cirrus CS4391 KZ :

https://statics.cirrus.com/pubs/proDatasheet/CS4391-4.pdf

I have lots of experience building & fixing my synths, and lots of experience working with electronic hardware products in my day job(s), but currently I do not have direct access to any of the tools needed to properly remove & replace this type of tiny SMT part (microscope, IC de-soldering tool, very fine soldering iron for installing the new part).

I'm in Oakland, just across the bay from San Francisco. Are any of you DIY guys here in the bay area, and do you have the tools to do this rework?

Maybe we can work out a trade? I have some nice new audio cables. Or you're welcome to come over here and go nuts on my massive MU modular. Or feel free to suggest something. PM me! Thanks.
nd595
Hi Dave,
I'm at the other side of the globe (Spain), but it would be quite an easy job if you have right tools - a good 6-8x magnifier, fine tweezers, hot air rework station (some are not expensive - I use a cheap AOYUE) and a syringe with a SMT solder paste.
Desoldering is easy - after a few seconds of heating with rework fan you just pick up the old chip with tweezers. Then you put a soldering paste over all contact pads - very little amount you need, but when you position a new chip on top and heat the paste, solder just crawls to the contact pads (remember - not too much!!!), and it is done. Quick and easy. Maybe you could borrow a hot air reflow station for a couple of hours?
In any case - Good Luck!
Dave Peck
Hi nd595,

Yes, I have lots of experience with the process of SMT assembly, both by hand and in huge automated manufacturing facilities, and I have experience with this kind of rework.

The problem is that right now I do not have any of the rework tools you described.

In the past, I worked as a full time engineer at several pro audio equipment manufacturers and I had easy access to SMT rework equipment. But for the past few years I am working with design companies and contract manufacturers that only do through-hole assembly in their designs and they don't have SMT rework equipment.

If anyone in the San Francisco area has these tools and could let me come over and do this small rework on this board, I'd be happy to work out some kind of deal with you. Thanks!!
Chrutil
Dave Peck wrote:
Hi nd595,

Yes, I have lots of experience with the process of SMT assembly, both by hand and in huge automated manufacturing facilities, and I have experience with this kind of rework.

The problem is that right now I do not have any of the rework tools you described.

In the past, I worked as a full time engineer at several pro audio equipment manufacturers and I had easy access to SMT rework equipment. But for the past few years I am working with design companies and contract manufacturers that only do through-hole assembly in their designs and they don't have SMT rework equipment.

If anyone in the San Francisco area has these tools and could let me come over and do this small rework on this board, I'd be happy to work out some kind of deal with you. Thanks!!



Hey Dave,
Christer here - from our meetup group -
I have a hot air smd rework station and thinly tipped iron where I regularly do 0.65mm pitch and recently a set of 0.5mm pitch stm32's.
I could probably do the rework or you are very welcome to come up to San Rafael and have a go yourself up here.
The main thing is if the chip is easily accessible on the pcb, do you have a photo of the surroundings?

Cheers
Dave Peck
Hi Christer! I just sent you a PM with contact info. Talk to you soon! This is fun!
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