Author Topic: Capacitor question (Read 8032 times)

Donomite · « **on:** January 10, 2015, 12:40:31 pm »

Hello I am performing a capacitor recap on home audio preamp. What can I use to support a cap that is about 20mm off the board. I was thinking hot glue? Thanks

wraper · « **Reply #1 on:** January 10, 2015, 12:46:25 pm »

Hot glue is not reliable, especially if the device will be exposed to cold or hot. Better to use neutral or special electronics grade (expensive) RTV silicone. Do not use acetoxy type (vinegar smell) as it causes corrosion.

SeanB · « **Reply #2 on:** January 11, 2015, 09:43:07 am »

Second avoiding the hot snot, and use the acetoxy free silicone. Why is the cap off the board? Can you not mount it with at least one side flush and use the silicone? I have also drilled 2 holes through the board ( avoiding traces and other components) to use some lacing twine to hold it down, along with a drop of varnish on the knot and on the cord to stick them to the component and keep it from coming undone or slipping.

Leadfootin · « **Reply #3 on:** January 11, 2015, 01:35:05 pm »

Make a spacer from some sort of plastic or hard rubber.

SgtRock · « **Reply #4 on:** January 11, 2015, 11:29:34 pm »

Dear Donomite:

--I use liquid electrical tape to provide hysteresis, and damp down any rocking due to low order harmonics, as well a Gs due to shipping and handling. It lasts well and is easy to remove. It is also good for scrape and nick repair. I have even used in in desktop PSUs to occupy space previously inhabited by arc enhancing dust bunnies, or woolly boogers as we called the in the Air Force.

"In choosing a hypothesis there is no virtue in being timid. I clearly would have been burned at the stake in another age."
Thomas Gold 1920 - 2004

Best Regards
Clear Ether

tautech · « **Reply #5 on:** January 12, 2015, 06:57:27 am »

Quote from: Donomite on January 10, 2015, 12:40:31 pm

Hello I am performing a capacitor recap on home audio preamp. What can I use to support a cap that is about 20mm off the board. I was thinking hot glue? Thanks

Welcome to the forum.
Are you trying to use a cap that is a different form factor to the original?
Seems most unusual.
If it is a power supply cap I wouldn't recommend this.
Often a resistor is "stood off" the PCB but a cap?
Power resistors have thicker leads for stand off use and to help conduct heat to the PCB.
We used to see ceramic spacers slid on the leads for stand off needs.
But a cap normally has quite flimsy leads by comparison, not suitable to stand off use.
Post a photo for the collective wisdom of the forum to guide you.

Edit
If you intend to use a Radial to replace an Axial, one way is to invert or lie down the radial, stick it down, sleeve and extend the leads to the through holes.
Not particulary pretty, but safe and functional for non-critical components.

Donomite · « **Reply #6 on:** January 12, 2015, 04:02:54 pm »

Thanks so much for all the support. I need to do a proper introduction but for now here is a pic of the power supply. Same value cap 1000uf 80v (nichicon) but 32 years of technology later...thus smaller cap.

tautech · « **Reply #7 on:** January 12, 2015, 07:17:05 pm »

Is there an opportunity to re-drill and still intersect with a meaty track for a good joint?
Sometimes you will see PCB's with 2 footprints for caps like these to cover the manufacturer if 1 part be unavailable. I suspect they do it to use stock they have on hand.

Otherwise put some "L" bends in the leads and get the caps closer to the PCB.
Sleeve leads.
Then stick them down.
As mentioned before RTV type adhesive Silicone is the preferred adhesive, but if you can possibly re-drill you won't need it.

Donomite · « **Reply #8 on:** January 12, 2015, 09:42:28 pm »

At tau tech...just looked under the board and the holes are already on the edge. I just figured out what you were talking about doing with new holes. Good advise for future work. Looks like I will go the RTV route. Just have to find the correct rtv.

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helius · « **Reply #9 on:** January 12, 2015, 09:52:06 pm »

Many series of radial elcos have multiple options for lead spacing (abbreviated LS). It is often quite hard to select lead spacing in online catalogs, but choosing the right spacing makes life easier.

tautech · « **Reply #10 on:** January 12, 2015, 10:05:25 pm »

Quote from: Donomite on January 12, 2015, 09:42:28 pm

At tau tech...just looked under the board and the holes are already on the edge. I just figured out what you were talking about doing with new holes. Good advise for future work. Looks like I will go the RTV route. Just have to find the correct rtv.

Sorry can't advise you of a local supply untill you put your country flag in your profile.

Donomite · « **Reply #11 on:** January 12, 2015, 10:10:57 pm »

United States. @ Helios....I did see the lead spacing when on the Mouser site. This was my first time ordering components. I'm learning a lot!

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tautech · « **Reply #12 on:** January 12, 2015, 11:21:00 pm »

Use something like this:
http://nz.mouser.com/ProductDetail/MG-Chemicals/1035-85ML/?qs=sbrGYOVz3HcWL8LpGHSdkg%3d%3d
You should be able to find something cheaper & local

Donomite · « **Reply #13 on:** January 13, 2015, 04:37:49 am »

I think I've got it sorted out. Two pieces of rubber. Maybe a couple drops of super glue to hold rubber to board?

amyk · « **Reply #14 on:** January 13, 2015, 04:32:19 pm »

I'd just bend the leads (carefully!) so they sit on the board.

That spacer just looks like some kind of weird audiophile snake-oil mod to me...

Excavatoree · « **Reply #15 on:** January 13, 2015, 04:57:28 pm »

Quote from: amyk on January 13, 2015, 04:32:19 pm

I'd just bend the leads (carefully!) so they sit on the board.

That spacer just looks like some kind of weird audiophile snake-oil mod to me...

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xwarp · « **Reply #16 on:** January 14, 2015, 07:54:13 am »

I'd put a slight bend in the leads of ALL those caps that aren't flush and make them flush with the board.

Sorry but with all those other caps sitting high up like that makes the board look like a hack job.

diegosfb · « **Reply #17 on:** January 16, 2015, 02:40:44 pm »

This may be not the best way to do it; but once I was in need of and had run out of glue, I have used silicone (silastic stile) like the one you use on your bathroom or kitchen joints.
I checked the one I used was non conductive and once applied it was pretty solid.

And it is pretty cheap and easily available (I had some laying around from some kitchen fix)

Hope it helps

voltz · « **Reply #18 on:** January 16, 2015, 05:24:02 pm »

Since this is an Audio Preamp, there is no problem at all using hot glue or hot snot as some call it. If this was a sub bass amplifier in a speaker cabinet or a high power PA system then yes I would advise against it. But since there is no or very little vibration in a preamp, go ahead, its absolutely fine. Its widely used in many prosumer and professional products for a reason not just cheapness. Its very effective.
However that gap between the cap and PCB is excessive and those rubber lifters don't look very nice at all (sorry). Do try to either get the correct capacitors and replace them. Or, simply bend the legs into a shape to make the caps sit as close to the PCB as possible. Then apply hot glue to seal neatly around the base of each cap. The closer you can get the caps to sit to the board the better and more solid and neat it will be.
Hope that helps.

mikerj · « **Reply #19 on:** January 16, 2015, 05:29:18 pm »

Quote from: amyk on January 13, 2015, 04:32:19 pm

That spacer just looks like some kind of weird audiophile snake-oil mod to me...

Black rubber is no good for audio applications. It darkens the sound and adds too much springiness to the mid-range.

wraper · « **Reply #20 on:** January 16, 2015, 08:14:23 pm »

Quote

Its widely used in many prosumer and professional

Only in crapsumer and crapfessional. Otherwise it is not hot glue.

voltz · « **Reply #21 on:** January 16, 2015, 09:31:43 pm »

Quote from: wraper on January 16, 2015, 08:14:23 pm

Quote
Its widely used in many prosumer and professional
Only in crapsumer and crapfessional. Otherwise it is not hot glue.

In your opinion

bithead9 · « **Reply #22 on:** January 17, 2015, 03:39:18 am »

I am with Amyk on this one. I'd bend the leads with a long nose pliers and make it flush. Or just bend ONE lead and have the other go straight through.

Donomite · « **Reply #23 on:** January 17, 2015, 04:47:16 pm »

Thanks for all the suggestions!! Any tips from you guys will certainly help now and down the road. I received the last 4 caps I needed for the preamp recap project. I will be posting pics of some components that I can't identify.


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Author Topic: Capacitor question (Read 8032 times)

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