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Old 7th March 2012, 02:25 PM   #1
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Default Heat sinks for LM3875TF

I am hoping for some advice and help

I have a pair of gainclone dual mono amplifiers, with a separate power pack

Each mono has its own case, approx 17 x 10 x 5 cm, of metal construction

I have noticed after extended use the case gets relatively warm

I was thinking of sound deadening each case, which could make heat dispersal worse (?)

Should I be thinking of fitting heat sinks to each LM3875TF ?

If so, how do I go about selecting a heat sink and is it just a case of selecting my desired heat sink and using the thermal adhesive tape supplied ?

Here is hoping for some help
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Old 7th March 2012, 03:50 PM   #2
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Can you post pictures?
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Old 7th March 2012, 03:52 PM   #3
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What specifically do you want to see pictures of ? General pictures of the amplifiers or of the circuit boards ?
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Old 7th March 2012, 03:59 PM   #4
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of where those IC's are mounted! are you using the chassis as a heat sink?
I build those amps long time ago from Audiosector and the IC's did not get hot at all, but again I used big heat sinks.
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Old 7th March 2012, 04:01 PM   #5
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They are mounted on a pcb, which is not in contact with the chassis, it has a fastening screw coming through the bottom of the casework which raises them approx 1cm from the bottom of the case
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Old 7th March 2012, 04:30 PM   #6
SoIL4x4 is offline SoIL4x4  United States
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So your saying the ic has no physical connection to anything in the enclosure aside from the pins into the pcbs.
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Old 7th March 2012, 04:37 PM   #7
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You are quite correct, no physical attachment to anything else in the enclosure, besides pins and pcb
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Old 7th March 2012, 04:38 PM   #8
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Quote:
Originally Posted by monitoraudio View Post
They are mounted on a pcb, which is not in contact with the chassis, it has a fastening screw coming through the bottom of the casework which raises them approx 1cm from the bottom of the case
What? are you saying those IC's are "floating" and nothing on the back to dissipate heat?. if this is right....YOU MUST PUT HEAT SINKS TO THE IC'S!!!!
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Old 7th March 2012, 04:54 PM   #9
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Hence my original post

What type of heat sink should I use and should I attach it directly to the chip ?
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Old 7th March 2012, 04:56 PM   #10
AndrewT is offline AndrewT  Scotland
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Look at the National datasheet for heatsink guidance.
Then I suggest you double their suggested sink size.
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