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Case Cooling
MUFF WIGGLER Forum Index -> Modular Synth General Discussion  
Author Case Cooling
synkrotron
Hi Peeps,

I'm posting this in General because I'm guessing it is something that may be an issue with any kind of modular system.

But, by all means, move this to Eurorack if you don't agree.


I have two cases, one is the Doepfer LC9 and I also have the Doepfer LCB.

The LCB is new to me and I bought it to expand our system and the LC9 fits nicely on top.

I don't have much in the LCB at the moment, just Metropolis, Pressure Points + Brains and a couple of smaller modules.

But Pressure Points has been playing up (I've posted in the Eurorack forum about the issue) and I am wondering if it is an overheating problem. Reason I am saying this is, I was practising with a new patch yesterday and by the evening the touch plates on PP stopped working altogether. I tried all sorts of things to get them working but to no avail.

Then when I turned on my system this morning all was fine again. For a time anyway. After a couple of hours the problem started again.

Hence the question, does anyone here bother with cooling their modular cases?

I'm guessing it would be an easy thing to do. I have a couple of 5" fans knocking around and they would work fine on 5 volts, so I could soon hook one up, after butchering my LCB case.


Thoughts?


cheers

andy
Joe.
I've never used active cooling, just vented blanks, and everything's been fine. An enclosed case with regulators in is basically an oven, and you're going to reduce the lifespan of things like electrolytic caps the higher the ambient temperature is in your case.

If you are going to modify your case I'd consider trying a grilled vent first, before installing fans.

(On the other issue, I'd try powering the pressure points in the LC9 and see if the problem persists in that case. )
felixer
good trick is to have an aluminium casing. that transports the heat to the environment. or maybe just make the top alu. my racks have alu sidepanels.
active cooling isn't such a bad idea. lots of very quite and small ventilators around. the larger ones use power from the wall so no need for a psu.
sduck
Most power supplies produce very little heat, and most modules are equipped with lots of cooling holes, although we do often block them off with patch cables. Built up heat shouldn't really be a problem.

What you could do in this specific case is unscrew the PP, and use it for a while propped up somehow, so there's more than enough space for air to get in behind it. See if the problem still arises.
felixer
nowaday it's often not the psu (with all those digital/switching devices). but the core temp of a transistor easy is over 100°C. and that adds up! and ic's contain dozens or 'm. good cooling is essential for the longevity of your gear!
synkrotron
Joe. wrote:
I've never used active cooling, just vented blanks, and everything's been fine. An enclosed case with regulators in is basically an oven, and you're going to reduce the lifespan of things like electrolytic caps the higher the ambient temperature is in your case.

If you are going to modify your case I'd consider trying a grilled vent first, before installing fans.

(On the other issue, I'd try powering the pressure points in the LC9 and see if the problem persists in that case. )


Thanks for your input here Joe smile

Some good points made.

I could try it in the LC9 but it would just be a test, of course, and for access it really needs to be in the LCB.

cheers

andy
synkrotron
felixer wrote:
good trick is to have an aluminium casing. that transports the heat to the environment. or maybe just make the top alu. my racks have alu sidepanels.
active cooling isn't such a bad idea. lots of very quite and small ventilators around. the larger ones use power from the wall so no need for a psu.


Interesting.. I'll look into that. I suppose I could adapt my LC9 and LCB cases...

cheers

andy
synkrotron
sduck wrote:

What you could do in this specific case is unscrew the PP, and use it for a while propped up somehow, so there's more than enough space for air to get in behind it. See if the problem still arises.


Yeah, good idea.

In fact, I could let the PP get to the point where the touch plates stop working, take it out of the case to allow it to cool and see how that goes...

cheers

andy
Joe.
you could also use 'hex standoffs' to effectively lift the module (10mm etc) out of the case, creating a vent around the entire module itself while still having it mounted to the rails.





.
synkrotron
Joe. wrote:
you could also use 'hex standoffs' to effectively lift the module (10mm etc) out of the case, creating a vent around the entire module itself while still having it mounted to the rails.


Mmmm... Like the sound of that... Might have some knocking around somewhere...

Thanks smile
synkrotron
I don't think I need to bother with case cooling...

I've just updated my Pressure Points post in the Eurorack forum.

Basically, I started having an issue again. So I powered down the LCB case so that I could remove some modules and panels and I estimate that is wasn't more than thirty degrees C in there.
Graham Hinton
sduck wrote:
Most power supplies produce very little heat,


The amount of heat produced by a PSU is proportional to the power drawn by the modules. A linear PSU will be about the same amount, a switch mode about 25% to 50%. The important information is what the total is and the easiest way to measure it is to use a cheap power "energy meter" on the mains input.

Up to about 250W may be dealt with by natural convection, you need inlet and outlet holes in the case such that cool air is drawn in the bottom and rises over the parts to be cooled and exits at the top. More holes anywhere won't help, you need to create an updraught otherwise known as a chimney.

Above 250W and you are going to need fan assisted convection.

Quote:

Built up heat shouldn't really be a problem.


Built up heat is THE problem. Even if not a lot it will still bake the components and shorten the lifetime of electrolytic capacitors which halves for every 10degC hotter they run at.

felixer wrote:
but the core temp of a transistor easy is over 100°C. and that adds up!


The power adds up, not the temperatures. Again the important thing is the total power and how it is conducted away. A heatsink is a misnomer because it suggests that heat magically disappears into it and many PSUs copying the PSU2 seem to believe that. Heatsinks have to get rid of heat as fast as it is created and many are too small to do that causing PSUs to thermally regulate, i.e. wobble when they get too hot. Heat enters a heatsink by conduction and leaves by radiation and convection. If they do not have enough surface area with a flow of air they will just rise to the same temperature as the components to be cooled and then they are no use at all.
sduck
Mr. Hinton is one of those people I don't mind getting corrected by - trust him!
ranix
I would measure the temperature inside the case before committing to a strategy.
synkrotron
Just popped in to say that I am reading all the posts here with interest.

I need to find a thermometer I can trust. In fact I think I might have a little electronic on in my box of plasters and stuff. It is normally used for measuring human temps but might be okay for this task too...

cheers

andy
ranix
there may be hot spots, especially in corners
Dave Peck
synkrotron wrote:
Just popped in to say that I am reading all the posts here with interest.

I need to find a thermometer I can trust. In fact I think I might have a little electronic on in my box of plasters and stuff. It is normally used for measuring human temps but might be okay for this task too...

cheers

andy


Best option would be to use temperature probe accessories connected to a VOM and follow established guidelines for where to place the probes (affixed to specific devices that you want to check, located near electronics for checking ambient temp, etc.) and how to plot the temp rise over time.

This stuff:

https://www.myflukestore.com/category/fluke_temperature
synkrotron
Thanks for the link Dave, I will look into that smile
Graham Hinton
Dave Peck wrote:
Best option would be to use temperature probe accessories connected to a VOM and follow established guidelines for where to place the probes (affixed to specific devices that you want to check, located near electronics for checking ambient temp, etc.) and how to plot the temp rise over time.

This stuff:

https://www.myflukestore.com/category/fluke_temperature


Those Fluke prices are really gouging! Most temperature probes are based on a "Type-K" thermocouple which is basically two wires of different metal bonded at the tip. You can buy bare ones for next to nothing or ones built into a stainless steel tube with a handle for not much more.
This sort of thing: https://www.ebay.co.uk/itm/assorted-temperature-probes-with-handles/32 2629533742?hash=item4b1e38002
They are terminated with an isothermal connector so you will need an adapter to 19mm spaced 4mm plugs to plug it in your DMM. Again, you don't have to pay Fluke prices. Where Fluke does shine though is that their meters have a specific degC/degF range which corrects the thermocouple characteristics and converts into a temperature readout, otherwise you have to calculate that from the raw voltage. You can also get dedicated digital thermometers (not the medical type) that have an isothermal socket to accept probes directly.
synkrotron
Yeah, I looked at the Fluke website and I don't think I can justify that kind of outlay at the moment.

You could argue that if it protects the investment into modular, and I must be getting up to around £3000 by now, that it would be money well spent.

But, for now at least, just while I get a handle on the heat situation through the summer months here in the UK, I am going to try something like this:-

https://www.thetortoiseshop.com/ta-digital-thermometer?language=en&cur rency=GBP&gclid=Cj0KCQjwxN_XBRCFARIsAIufy1bpjdaFAu63KvCr_dUzyHRlVzVXn9 CYPNU-EAXVCOeAHXkx16TGtaoaAoC_EALw_wcB

Might sound a bit of a joke but I quite like the cost of this unit. In fact I could buy one for each of my two cases. And it gives a reading of both inside and outside, so I can see how ambient temps are affecting temps inside.


cheers, and thanks for all the input so far smile


andy
Graham Hinton
synkrotron wrote:
Might sound a bit of a joke but I quite like the cost of this unit.


Do a search for "K thermocouple thermometer" on eBay. Better prices, better choice.
synkrotron
Graham Hinton wrote:
synkrotron wrote:
Might sound a bit of a joke but I quite like the cost of this unit.


Do a search for "K thermocouple thermometer" on eBay. Better prices, better choice.


Will do, thanks Graham smile
JohnLRice
FWIW I use an Infrared Temperature Gun, an old Fluke 62, as a quick way to check. It wouldn't be useful for checking the internal temps of a case unless there is a fairly large opening but just scanning the face plates, case surfaces and power bricks can give you clues to problems, for instance get readings when things are working well and take new readings when things are showing problems and compare. The gun is quick and easy because it reads fast and remembers the highest temp during a continuous scan.

I paid $100 for mine about 10 years ago but you can find them used for about $50. That said, there is a huge flood of knock-off look alike ones now that are only $1 to $20 new! eek! I'd suspect that these cheap ones wouldn't work as well or be as well made as mine but, maybe the technology used in these has become inexpensive? hmmm.....


Regarding adding fans to cool a case:
One of my favorite DIY stories gone wrong was told to me by a friend who used to work at a pro audio repair shop in the 70's. A customer had a large power amp with massive heat sinks but they were pushing it too hard or had it somewhere without adequate ventilation etc so the thermal protection circuit kept cutting off the output, which of course is a bad thing during a performance. They did the seemingly logical inexpensive solution and added a fan to help cool the heat sink. The result? The amp failed in a bad way. Unwittingly (or maybe on purpose?) the spot they happened to aim the fan at was right where the thermal sensor was, which kept that area cool enough to prevent the protection circuit from kicking in while the rest of it continued to over heat and all the power transistors fried. Moral of the story: having a complete understanding of how something was designed and intended to work is important before making any modifications, especially where high power or critical performance is concerned. (not that I always follow that rule oops )
synkrotron
I borrowed a digital thermometer today that reads current, lowest and highest temp.


So I checked the ambient temperature first, which was around 24 deg C and then stuck it inside my LCB case.

After having my system on for over twelve hours, the maximum recorded temperature of 27.2 deg C.

So, for the moment at least, I do not appear to have a real issue.

That said, I don't know what sort of temperature a modular system should be running at but this doesn't sound particularly high to me.

my LCB is only half full yet, so I will need to check again once it is full, and also check when the ambient temperature is up near the high twenties.


cheers

andy
synkrotron
JohnLRice wrote:

Regarding adding fans to cool a case:
One of my favorite DIY stories gone wrong was told to me by a friend who used to work at a pro audio repair shop in the 70's. A customer had a large power amp with massive heat sinks but they were pushing it too hard or had it somewhere without adequate ventilation etc so the thermal protection circuit kept cutting off the output, which of course is a bad thing during a performance. They did the seemingly logical inexpensive solution and added a fan to help cool the heat sink. The result? The amp failed in a bad way. Unwittingly (or maybe on purpose?) the spot they happened to aim the fan at was right where the thermal sensor was, which kept that area cool enough to prevent the protection circuit from kicking in while the rest of it continued to over heat and all the power transistors fried. Moral of the story: having a complete understanding of how something was designed and intended to work is important before making any modifications, especially where high power or critical performance is concerned. (not that I always follow that rule oops )


Interesting story that, John, and makes a lot of sense.

Thanks smile
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