Hi all:
Once again, complete newbie here. Building a Chipamp.com LM3886 dual mono kit.
Now that I've established that my PSU boards are working fairly well, I am turning attention to finishing the two amp boards. Both are completely soldered except for the actual op-amp chips.
My question is, someone told me to mount the chip to a heatsink first, before I solder the chip to the board. Can't remember why. Is it not okay to just solder the chip to the board and then mount chip to heatsink afterwards?
I ask only because I noticed that once soldered to the board, the chip may not sit a 90 degree angle to the board. But I also noticed some flexion in the leads, so I assume that is for tweaking so you can gett chip mounted to both board and heatsink squarely?
Once again, complete newbie here. Building a Chipamp.com LM3886 dual mono kit.
Now that I've established that my PSU boards are working fairly well, I am turning attention to finishing the two amp boards. Both are completely soldered except for the actual op-amp chips.
My question is, someone told me to mount the chip to a heatsink first, before I solder the chip to the board. Can't remember why. Is it not okay to just solder the chip to the board and then mount chip to heatsink afterwards?
I ask only because I noticed that once soldered to the board, the chip may not sit a 90 degree angle to the board. But I also noticed some flexion in the leads, so I assume that is for tweaking so you can gett chip mounted to both board and heatsink squarely?
Unless it's a very small clip-on heatsink, the sink and the board have to have a 'fixed relationship' - i.e. be securely fastened somehow. You don't want the sink hanging on the chip leads.
There's lots of 'extra' lead length on the chip to allow for small adjustments before soldering.
So, IMO the advice to mount the chip on the sink first is correct, and will usually be easier. But, it depends on the physical layout you have in mind.
As long as there's no mechanical stress on the solder joints you should be OK.
I've put together a few chip projects. Those, and scavenging parts from scrap hifi equipment and power supplies, gave me an idea of how to arrange the heatsinks.
VictoriaGuy:
Thanks for that. So, you recommend I get my heatsinks first, eh? I was thinking of just using a smaller (but not that small) heatsink/heatpipe I happened to get from a Denon receiver. Thought I'd use that for testing. Even for testing, you recommend I fasten the chip to heatsink first before soldering the chip onto the board?
Thanks for that. So, you recommend I get my heatsinks first, eh? I was thinking of just using a smaller (but not that small) heatsink/heatpipe I happened to get from a Denon receiver. Thought I'd use that for testing. Even for testing, you recommend I fasten the chip to heatsink first before soldering the chip onto the board?
I've used a 'temporary' heatsink on cheap (eBay) chipamps.
However, it's a PITA for me to unsolder/remove anything with more than a couple of leads.....'relocating' a multi-leg chip is no fun....so possibly 'delayed gratification' would be better...
But wait a minute, not trying to be difficult (just an extreme newbie), but then how do I test anything without tapping holes in case and etc. And once I've done that, I'm kinda committted, right?
It's certainly possible to mark and drill/tap the heatsink from the chip hole when you are going to 'final assembly', but you need to be very careful that there is zero strain on the chip solder joints. You may need to mess with shims/washers, etc...but it will let you test with a temporary sink.
You can figure it out - just make sure that those solder joints are not stressed.
Looking at some commercial stereo gear from 20-30 yrs ago can give you ideas of how it should be done. Yard sales, auctions, free listings online can all provide stuff for a few dollars if you are patient. (Also, that gear can be a good source for power supply and chassis (slap on a new front faceplate) for your chip projects.)
"But wait a minute, not trying to be difficult (just an extreme newbie), but then how do I test anything without tapping holes in case and etc. And once I've done that, I'm kinda committted, right?"
If you just want to prototype and preserve the chip for final assembly, keep the leads long and snip of the soldered ends when ready for assembly.
If you just want to prototype and preserve the chip for final assembly, keep the leads long and snip of the soldered ends when ready for assembly.
This is my first post here (and maybe not a good one) but on my builds I solder the chips to the boards and playing around with placement in the chassis. Once you know where they'll be placed you can drill/tap/etc and just screw them against the chassis for testing. The chassis itself should provide enough heat dissipation for testing provided it's made of metal.
I've actually ordered one of those 3886 chipamp kits recently and am looking forward to building it.
Cheers!
I've actually ordered one of those 3886 chipamp kits recently and am looking forward to building it.
Cheers!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.