If it was well designed with a voltage reg which shut down with heat, probably OK. But check for overheated electrolytic caps. Might be worth replacing them anyway, as they are likely to have a shorter life with heat.
We've never done this for this type of amp before. The case is diecast and ribbed so presumably radiates heat reasonably well.
We sometimes fit mains voltage fans in the wall of cabinets that are a bit crowded. We use domestic thermostats for control.
Bill
What colour is it?
Serious question - if it is a metallic aluminium finish then you can probably improve its cooling performance by adding the thinnest coat of matt black paint you can find. I got caught with this once with a prototype in an as yet unpainted mirror aluminium box which overheated.
It was fine in production boxes with any colour of paint on - apart from metallic finishes they all approximate black in the thermal IR band.
I am wary of things with moving parts in awkward places. YMMV
In message , Martin Brown writes
Many of the 'big boy' cable TV amplifiers have bare ribbed bodies and lids. This is essentially to increase the surface contact with the passing air (which any covering of paint will reduce), rather than to increase direct radiation. I don't think paint is a good idea.
paint makes a slight difference or better still anodising.
But airflow is the absolute major factor.
Stuff 'in inuslation' is simply NBG
In message , The Natural Philosopher writes: []
Did the model therefore crash? If so, not too badly, I hope.
4
Still got line noise in your sig, I see:
Flat spin from 20 feet up. Not too badly damaged, but it's always flown a bit sideways ever since the repairs
I put in a bigger speed controller with a bigger regulator chip.
spray it with matt black paint to emit even more heat.
Well perhaps it hasn't suffered that much but caps are the prime cause of failure in most set top boxen and similar;!
I've never been entirely convinced. I _think_ it might radiate more, but also absorb more (e, g, if sunlight should fall on it).
Ultimately if it doesn't have any internal heating they end up eventually at the same equilibrium temperature in sunlight. It is just that in one case most of the sunlight is reflected and what little is absorbed is re-emitted only with difficulty. Try it with baco foil vs black paint in sunlight.
White vs black paint is different since the former reflects most visible light and near IR but is still a good thermal IR radiator.
Aluminium or any other metallic surface reflects most electromagnetic radiation and is at the same time a poor thermal IR emitter as well.
Out of sunlight there is no contest. It made the difference between a device that lasted less than half an hour to thermal shutdown (bright mirror finish aluminium sheet prototype) and one that was quite warm to the touch but entirely reliable (any colour of paint will do). It ended up black because that made it effectively disappear when in use.
Radiative cooling starts to dominate when the object is around 30K above ambient ~300K and goes up as the fourth power of absolute temperature.
Around a very long time ago now i used to work in a TV repair shoppe we serviced a lot of the Philips G8 chassis sets. OK they were for their time but we had a lot of BU208 the line output stage transistors fail they seemed to be running quite hot on plain ally heat sinks.
A can of matt black spray saw the number of them over time reduced we sprayed the heatsink's out in the customers home as well as the workshop. Never as best i recall changed one 208 on the blackened heatsink's!
FWIW..
On Fri, 6 Jul 2018 11:29:23 +0100, Martin Brown wrote as underneath :
Informative post - thanks! Thinnest paint? Perhaps permanent magic marker worth a try for quick and easy? C+
A dye based black might only be black in the visible though. So might not have the same effect. You would have to try it and see.
Domestic heating 'radiators' ought to be matt black for the same reason, but for some reason they are always shiny white or chrome.
As I've already suggested about cable TV amplifiers, the body and the lid are usually ribbed and finned (especially the big ones). This is not so much to increase the dissipation of heat by radiation, but to increase the area of contact with the (hopefully) passing airflow (ie convection). They are invariably bare pressure-diecast aluminium. If painting or anodising really helped, I feel that they would probably do it.
Actually extrusions are more common in bigger power setups than castings
As an ex designer of power electronics, you are ALMOST correct.In free air a finned heatsink with preferably vertical fins is as good as it gets shapewise. Black paint maybe ups it by 10-20%. Its really not a huge difference at all.
Fan blowing it increases dissipation 5-20 times!!!
Domestically the percieved ugliness of black isnt worth the 10% reduction in size.
Not for this sort of equipment:
You will see that some of the fins are distinctly non-vertical.
Most of those units are bare. IIRC, those that ARE painted only have a thin dusting of grey.
The only equipment I've seen that was painted black was something I was involves with 50 years ago (and, IIRC, the paint was rather thick - to beautify a rather rough sandcasting). The second generation was thinly painted grey.
Mostly domestic radiators emit mostly warm air by convection as well unless you run them *very* hot when radiation dominates. Almost any colour paint that isn't shiny metallic is black in the thermal IR.
Metallic surfaces make very poor radiators but don't affect convection.
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