The New T-amp PCB

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Okay, its official. The new T-amp PBCs are now being produced without the solder heatsink. Ive had correspondance with a representive at Sonic Impact Technologies, and he stated that the new solderless boards arent a manufacturing error but a change in production. So for the SIs' intended use, the heatsinking isnt neccessay apparently. He was quite helpful and responded quickly to my email and I followed up with a phone conversation. So Ive moved the discussion out of the "faux pas" thread since its not now appropriate.

For those that dont know what Im talking about, check this thread for pictures and a brief discussion.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=55302

So my next project is to hook one up and see how it fairs with a 4 ohm load for an extended period of time.

amt
 
I've modded two SI boards -- one with the solder blobs, and a new one without. I've been using those self-adhesive aluminum heat sinks mentioned in another thread.

I didn't do a scientific test, but the new "blobless" board definitely heats the sink to a higher temperature than the older board.

These little heat sinks are the EXACT size of the Tripath chip, and stick right on. They even come in difeferent colors!

Since they are very cheap insurance, I suggest every modder pick up a few!

Rich

Here's a link: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3673&item=6760147846&rd=1&ssPageName=WDVW
 
Eric,

The heatsink sticks right onto the top of the chip. The chip sits on one side of the board, so there's no way to stick one on the bottom side.

On the older boards, the solder blob sits all around (maybe under?) the chip and helps to dissipate the heat. Looks like the new boards have small holes drilled through the areas where the solder slug used to sit, but from what I've read on the boards, this little bit of airflow doesn't cool the chip as well as the slug.

Best,
KT
 
The holes definately dont provide enough airflow to cool the chip. Heatsinking is a must if the amp is operated much past a watt or two. My solution has been to flow solder on the top of the board and onto the copper tap that protrudes from the sides of the chip. One side is blocked by the power/input wires but the other side is open. While the puddle of solder is still hot, I attach a piece of copper to it which is about 1/2 x 1/2 x 1/8" . This piece of copper bar pulls the heat from the chip nicely and dissipates it well. I recently started attaching the copper heatsink to the bottom of the board by filling the holes under the chip with solder. I keep a 20lb piece of aluminum chilled in the freezer to pull some of the heat from the board once the soldering is done, since it generates quite alot of heat. All my amps have been built this way since the slug was eliminated.

amt
 
Had a bad experience with a 'stick on' heat sink before that was forced on me, on a 32 bit RISC Controller Design I did. After enough power/heat cycles, the adhesive gave up and the heat sinks turned into big chunks of bad stuff rolling around on the circuit boards while the processors roasted themselves to death.
 
Ive used metal based epoxy to glue a small PC chip heatsink to the plastic case and then dremelled an opening on the bottom of the board to check the heat. Although the heatsink on the top helps, it doesnt pull enough heat out of the package, IMHO. The copper slug is still smoking hot. Trying to pull the heat out of the copper, through plastic and then adhesive just isnt as effective as drawing it out with solder on copper. I know its more of a pain it the *** but...

amt
 
thanks guys!!!!!!!!! i think i do the heatsink with the arctic silver...the solder slug with copper sounds good also...its just where in the world could i find copper that thin...? anyway, i'm slowly working on getting all the info i need for the SI mods.....i really really wish there is a step by step web site somewhere like there is with the toshiba 3950 dvd player.........u guys have been a wealth of info and it is mucho appreciated!!!!!!!

thanks!!!!!!!!
 
just read your new post amt...........i should solder slug the top and bottom with a thin layer of copper then, eh? hmmmmmmm...............any source for the copper? is it tricky? how do i use the frozen block of metal u mentioned earlier to cool the board? or should i just stick with cat5 braiding and easier mods......? grrrrrrrrrr.....

thanks again :)
 
You either build up a pool of solder that flows onto the little tab on the top of the board OR drop solder into the holes on the bottom of the board, so that it contacts the chips copper slug bottom. Make sure to pre-heat the copper and tin it where you attach it. Its not hard, but requires care so that you dont over heat the chip and board and get solder where it shouldnt be.

Copper flat bar is usually available at most metal supplies. Small scraps can be found at metal recyclers too. A suitable piece may also be found at the hardware store as electrical parts, shims etc.

After the heatsink is mounted, the chip/board need some cooling. By touching the heatsink to the cold aluminum, you can suck the heat right out of the works. Just do it slowly. Rapid temp change isnt good.

I will try and post a picture within the next couple day to help illusrate.

amt
 
cool..!..pictures always help! another crazy question....how 'bout solder sluggin' a heatsink...i've had my amps now for over a week and i'm just itchin' to mod.....too, has anyone see these http://www.atiresearch-anodized.com/products.html i like your cases amt but the model ATI 735U looks to be more my speed...are the U.S. alternatives to a chassis like this...these are from Taiwan and the postage is a bit steep....
 
Well heres a shot of the copper heatsink. First I heat the copper and tin the attaching side. Then I flood the bottom of the board, making sure solder reaches the chip and has heated it sufficiently to attach. Then I place the copper on the board, re-heat the puddle so it attachs and then add additional solder to the joint.

This has to be done quickly, so the copper and the puddle dont cool down to the point of requiring complete re-heating. Once done, I contact the copper to my frozen aluminum chuck, off and on, until I feel the plastic case cool to what would be warm operating temp.

amt
 

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amt said:
Well heres a shot of the copper heatsink. First I heat the copper and tin the attaching side. Then I flood the bottom of the board, making sure solder reaches the chip and has heated it sufficiently to attach. Then I place the copper on the board, re-heat the puddle so it attachs and then add additional solder to the joint.

This has to be done quickly, so the copper and the puddle dont cool down to the point of requiring complete re-heating. Once done, I contact the copper to my frozen aluminum chuck, off and on, until I feel the plastic case cool to what would be warm operating temp.

amt

Thanks for the pic - and explanation. I have just been taking a closer look at my SI's. I take it that there are no circuit board traces running beneath the 2020 chip otherwise these would be shorted out by soldering through the holes.
As the SI boards are not the best quality (so I have read!) should it not be possible and easy to cut out the 'holed" part of the board thereby exposing the base of the 2020 chip onto which a heat-sink could be attached? Anyone attempted this?
CambshireGordon
 
Ive done that too. Its more work and adds another risk of board damage. Pulling the heat out of the chip slug with solder is very efficient and easy. You avoid damaging the integrately of the cheap board as well, by just flooding the holes directly above the chip. If you want a traditional heatsink, just attach a piece of aluminum, to which you can affix a small finned sink. On my amps, the copper sink is actually on the top of the board (boards are flipped so chip/components are facing down) and within a few mm of the chassis. So heat is radiated to the chassis and convection through the vent holes draw out the heat. You can feel the copper sink getting much hotter than the chip case as it absorbs the the heat. If I were to go for the maximum sinking possible, I would attach larger piece of aluminum, in which a couple of threaded holes have been added, and then a large sink could be screwed to the plate or it could be attached to the chassis.

amt
 
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