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Old 12th April 2005, 10:17 PM   #1
amt is offline amt  United States
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Default SI PCB faux pas?

Just started tearing into my latest shipment of T-amps and found that the first two I liberated from the cases had a strange look to them. It is the look of no lumpy solder flowed on the boards. Its been understood that this was for heatsinking, and so its either been deemed unneccessary or its a manufacturing oversight.

Anyone else seen this on newly acquired boards? Mine are from PE.

amt
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Old 12th April 2005, 10:26 PM   #2
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Default Awesome!

I just got two new ones from PCMall. The quality has shifted into high gear with this batch.
The solder slug is not needed. The small heatsinks that Mexx Mexx has might be though.

George
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Old 12th April 2005, 10:36 PM   #3
amt is offline amt  United States
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How about for those that dont use an add-on heatsink like people who dont open the amps up? I would have though that dissipation at full output would require something.

So you believe this is intential and not an error? If so, that good to know because Ive got alot of these.


amt
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Old 12th April 2005, 10:43 PM   #4
BWRX is offline BWRX  United States
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i've been doing the THD tests and such on one of these new ones (see the stock SI spectrum thread for all that jazz) and hadn't even known there was a difference with the new ones. twice now i've triggered the thermal limit and the amp has shut off. the first time it happened i thought i killed the amp, but i wasn't doing anything wrong other tahn driving it pretty hard doing the intermodulation distortion test. it seems my modified amp (has the second revision board) has never gone into thermal protection when doing the same tests. granted, it *might* have better ventilation in the aluminum case, but it can't be that much better next to the heatsink of the voltage regulator, which gets pretty damn hot when the amp is driven hard. i would argue that the solder slug is needed for better cooling if you drive your amp hard enough or have a difficult 4 ohm set of speakers. that or some kind of smaller heatsink attached to the area where the solder slug should be.
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Old 12th April 2005, 10:55 PM   #5
amt is offline amt  United States
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I just looked to see if I could attach one but the chip actually floats above the board. The perforated holes need to be filled with solder until they contact the bottom of the chip. Can a solder bridge be built from the little metal taps that protude from the sides of the chip, w/o damaging something?

And I wonder if tripping the protection has any ill effects on the sound like it seems to with ICs.

amt
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Old 12th April 2005, 11:03 PM   #6
BWRX is offline BWRX  United States
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Quote:
Originally posted by amt
And I wonder if tripping the protection has any ill effects on the sound like it seems to with ICs.

amt
i ran the THD tests after the protection circuit had tripped and obtained practically the same results as i did before it was tripped. whether or not that correlates to the amp sounding worse i don't know. i haven't actually listened to my test amp because i was just using it for determining baseline measurements to compare the modded amp to.

it would take a LOT of solder to make a solder slug for one of these things. i only have very fine kester 44 rosin core and that would take forever to make the slug assuming my iron could get the thing hot enough for that long... maybe the'yre just cutting back on the cost of solder to make a couple extra bucks per amp
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Old 13th April 2005, 12:48 AM   #7
Pano is offline Pano  United States
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This can't be good. The Tripath docs call for the solder slug for cooling. Obviously the PCB is made for it. Even with the slug, the chip gets to hot to hold.

There must have been a slip up in the factory. Odd that the boards got all the way thru the assembly like that.

AMT, I know that you emailed S.I. about the problem, it will be interesting to see what they have to say, if anything.
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Old 13th April 2005, 03:04 AM   #8
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Default Mine too

Just opened one of my new last week ones. It has the naked board also.
It sure looks better than the solder slug. The quality of the soldering seems a little better also.
Hope it is not an issue. Maybe the holes in the board will let cooling air to the bottom of the 2024. I cannot tell by looking, but on the old ones does the slug touch the bottom of the chip?

George
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Old 13th April 2005, 03:14 AM   #9
toddsts is offline toddsts  United States
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Hey amt, why don't you try using some of this:

http://www.arcticsilver.com/arctic_a...l_adhesive.htm

to glue a heatsink to the back of the chip. Should conduct the heat but not the electricity.

Todd

Edit - It may be a mistake but I think its cool you can see through the PCB and see the heat slug on the backside of the chip. Also, it should make it less confusing to trace out the circuit. BTW, in case I wasn't clear I meant use the compound to fill in the hole leading to the heat slug on the back of the chip and then attach the heatsink with the compound.
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Old 13th April 2005, 03:27 AM   #10
BWRX is offline BWRX  United States
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electrically conductive materials are almost always better at conducting heat as well as electricity. that's why tripath says to use a solder slug as a heat sink on the back of the TA2024 chip. i've seen another chip with a heat sink on the opposite side (cant remember if it's a TA2024 or not). it almost seems that would've been a better one to use for our purposes, but not so for the space constraints of the molded SI chassis. but i guess that's how it goes in the DIY world. it seems as though the 41hz kits will be all the rage very shortly. especially if the board is reworked to include discrete signal path components (hint hint ).
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