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Better Heatsinking?

QSilver

QSilver

Super Member
I picked up an SX-V80 this week having clocked the magic words "Non-Switching-Amplifier" on the front.

After a lot of dusting, its working pretty well apart from a bit of a DC offset drift on the left channel and some slightly jumpy trimmers that will soon be replaced.... the amp looks to be a similar if not the same amplifier used in the SX-D5000 so I set the idle current to 70mV until I can find a reference to its own service manual.

After cleaning off the power supply board, it looks like a lot of the transistors are running hot, which isn't a big surprise having got the SX-D5000 and other receivers that like to cook power boards...

There looks to be some room above the power transistor heatsinks for a fan or two if I could make that work somehow and try to stimulate some airflow to the power board... I could move some of the transistors to a bigger heatsink next to the board with some of those JYK plugs (computer fan style plugs). I'm not quite sure what is best and wondered what people's opinions of it would be.

Maybe better heatsinks would be good enough. I'm guessing, and maybe someone can confirm this, that the original ones aren't very good...?
 
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Fans will tend to increase dust deposits. Heat sinks using natural convection would be my first choice unless the thermodynamics don't support the power dissipated.
 
Watthour said:
Fans will tend to increase dust deposits. Heat sinks using natural convection would be my first choice unless the thermodynamics don't support the power dissipated.
Click to expand...

Yes, that's true about the dust... my thought with the fans was that there was enough room and there seems to be a lot of transistors on the power board that chunk out a lot of heat... I had also thought about moving them off-board to a new heatsink or heatsinks just next to the power board if there is room. I might need to fabricate a plate for them to sit on.

I took a couple of pictures showing the power board and the space between it and the big heatsinsk for the outputs.

I cleaned it all after I took the second picture but you can see where the power board is getting baked in places...
 

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I have taken thick silicone pads that I got from old plasma TVs and put a small piece under the board by the hot transistors to help pull some of the heat off. I don't know whats below your board there, but if there is metal below, it will pull some of the heat off to it.
Just an idea.
 
Thanks for the tip. I took a look at the bottom of the board yesterday and reflowed some of the tired looking transistor joints. There isn't any metal underneath... there is another board for speaker selection underneath it.. Maybe a silicon pad would help anyway? I'm thinking that maybe the best thing will be to try and put them onto new separate heatsinks.
 
Well, I ordered some heatsinks but I don't think there is enough room in the case to upgrade all the transistors/regulators that need an upgrade - its quite tight!

For the moment, I've made a small fan controller that can run off the 12VDC+ supply on the power supply board which monitors temperatures and controls a 12cm fan. This has dropped the temperatures from 102°C down to around 45-50°C which very little extra noise.

I have fitted heatsinks to another reciever (SX-D5000) and I'll be testing them next week....
 
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