a basic diy question for my chip amp

[then_dude]

hello everybody,

i have a pcb transformer to feed my chipamp. but how do i stick it to the case ?

there are solder leads on the pcb transformer, but they are on the underside of it. so i will put the transformer up side down. but then: how to make shure the transformer stays at place ? : with glue: but then maybe the transformer needs cooling prevented by the glue ?

could somebody give me some clues how mechanica parts are attached in a case.
1)bolts
2)glue

but these two options might not work. and if i wanna make shure the transformator doesn't resonate and makes the case resonate to : how to acomplish that ?

thanx a lot
greetings

[Vikash]

Some PCB Transformers have mounting holes which you can use with standoffs.

Like this:


Vikash

[AndrewT]

The mains connections are under the insulated transformer case.
It is intended that the connections can never come into contact with the chassis.
Re-think whether you can safely mount this without a PCB and insulating panel.

A thin layer of silicone adhesive over the whole of the top surface of an upside down mounted transformer probably conducts more heat to a metal chassis than could be conducted/radiated to the air/surroundings. But you must still ensure that failure of the glue will not allow the transformer to move to a dangerous position. A mechanical "belt & braces" fixing could solve this issue (nylon ty-wrap?). You still have to make the mains connections safe from probing kids and unwitting adults.

[then_dude]

thanx a lot for the nic pics and fine info

1)it has holes in it, but you need to use self taping, so i don't like that idea; and if i would do that, i would put some kind of thin layer of plastic under the transfo, so that i'm shure; (i know it sounds a bit paranoia, but it's not for me, so i want it to survive a war)

2)glueing it up and brace it with ty wraps sounds good.
do you have any recomandation on glue. a lot of times you read: will never get loose, but in practice it does. so do you know something that glues metal and plastic, can even conduct heat quite well and never ever gets loose ?

thanx a lot

[AndrewT]

Hi,
I use clear silicone window sealer as a glue.
It sticks most substrates together very well.
It is better than the orange stuff used for assembling engine and gearbox casing/castings. It resists hot oil and petrol when "in the joint" and allows a no gasket assembly even around the high pressure oil ways in the engine block. It resists UV exposure and seems to be weather proof.
It remains "rubbery" for a long time and so resists vibration, I have even used it in lieu of "loctite" for a vibration resistant fixing on racing cars (they vibrate).

I am confident that a clean chassis and clean transformer will bond well to this soft adhesive.
Just play safe and include another fixing. If applied thin it will conduct some heat and if you ensure there is no air in the interface it will conduct better than simply clamped on.

[then_dude]

well maybe i use that, i had just seen what the prices were of high quality glue, good god that was quite a schock. i understand that it is very good quality glue, but something like 50 dollar for 40gr of glue. well then i just take the best silicon tube out there and stick it to the case.

i have also still lying around: epox 2 components, could use that to i suppose

thanx

[AndrewT]

Originally posted by then_dude
........... epox 2 components, could use that to i suppose

epoxy goes hard and becomes brittle when it sets.
I think that a plastic case subject to heat (thermal expansion) and a chassis plate that could twist or sag when lifted will break a brittle joint.

[quickshift]

Sikaflex 921 is also an very good adhesive for this type of application. It's a marine sealane / adhesive so it waterproof and weatherproof. It remains pretty flexible, forms a very strong bond and sticks just about anything to just about anything else. I've used it to bond an undertray to the seat unit of my track bike amongst other things.

http://www.sikaindustry.com/ipd-ma-products

Also available in small squeezy tubes.

[AndrewT]

Hi Quik,
thanks for that link.
I have been looking unsuccessfuly for a robust adhesive to join the trailing edges of a wing section made from glass and epoxy resin. It must be reliable since I will be doing upto 130mph and cannot take a risk with failure of this bonded edge.

[quickshift]

Hi AndrewT,

You're welcome, I hope you find something suitable there.

What series does the car race in if you don't mind me asking?