PC 3 Plate Choke needs Re Coating.

[EL84Fan]

Hi, Apologies if this question has been asked a million times already but...

When my S.E.X. kit arrived the Power transformer and the two Plate Chokes had hexagon patterns on the surface, probably due to being placed on something whilst drying?.
Not a problem at all except the Plate chokes will be seen as they are on top.
I have rubbed down and used Isopropanol to De grease them ( did not sand the feet ).
The next thing i am planning on doing is Clear Coating just to offer some protection.
Will clear coating be ok or would thermal cycling be a problem?
I have supplied some pictures of what i have done and what spray i am considering using.

Any advice would be very appreciated, Thanks.

 

[Paul Birkeland]

You can sand all the visible surfaces of those plate chokes since they have steel covers.  I have not used that particular Rustoleum product, so I have no idea what the outcome might be

 

[ccmccull]

I've used this lacquer and it works well. For the PC I just cleaned with acetone. Mine didn't need sanding.

 

[EL84Fan]

Thankyou for your replies,  I shall give this clear coat a go and see how it turns out.

Would you recommend roughing up the surface before spraying so it can key better or get away with leaving it smooth?

 

[Paul Birkeland]

I think sanding in one direction will give you a nice appearance under the clear.

 

[ccmccull]

If you decide to sand, I recommend a very fine paper and a super light touch and especially light on the edges. 1500 grit. Even at that grit you will see some etch marks through the clear coat. I think it's mostly an aesthetic choice, the lacquer probably doesn't need the keying because this part will never get any wear. But that's just my guess...

On various kits, I've done 400 grit on one transformer bell, 800 on another, 1500 on another, and nothing on these plate chokes. I like the look of 1500 or none best.

 

[EL84Fan]

Thats great thank you,

I shall get started on that, Thanks again.

 

[Mucker]

I did a coarse sanding on my S3X bell and chokes and the polished all with Mothers Mag aluminum polish only because I kept the top plate original and didn't want too much of a contrasting look.

On my new Crack, I did about 15 minutes of polishing on the bell. Depending on the time spent, it is possible to get a very nice finish with Mothers Mag.

Mine was all hand done. Using fine grit sandpaper and a buffing machine could probably turn out an amazing piece.

 

[EL84Fan]

Thanks Mucker, Looks really nice. Are you going to spray them or leave them uncoated? I was originally thinking of leaving mine bare but wondered if they would tarnish over time.

 

[Paul Birkeland]

If you leave steel uncoated it will rust.

 

[Doc B]

For what it's worth, Mothers mag polish is for aluminum and that end bell is steel. Basically that means way more work than necessary to get a finish. An easier way to get there is with compounds designed to polish steel. Black emery with a sisal wheel works very fast on carbon steel.

 

[Mucker]

Good info Doc! I just used the MM because that is what I had on hand and didn't want a mirror finish, just a near match of the plate. I bought it to restore the grungy disco dots on my SL-1200 turntable platters It works great for that.

EL84Fan, I haven't bothered with coatings. The bell from my 2014 Crack has never had a molecule of oxidation, but when you live in the Nevada desert, it's not too surprising.

 

[Big Bamboo]

I am building a sex 3.0 and wanted to treat/protect the PC-3 plate chokes. Specifically, I wanted to paint the top "U" shaped strap the color of my top plate. The bell on both sides, I wanted to protect with clear coat.

On the bottom there are tabs which, if pried up, should permit disassembly of the parts. This would make it easier than masking fully assembled.

But I wouldn't consider doing that without checking here first. If it's not a good idea to disassemble, then I will probably clear coat the whole thing.

Thanks for advice

 

[Paul Joppa]

It's actually a very bad idea. Choke laminations are not interleaved, having a gap of non-magnetic material (actually paper in the PC-3) between the stack of E laminations and the stack of I laminations. The only thing holding them together is the channel frame.

 

[Big Bamboo]

Thank you for the explanation, Paul. I will abandon that idea.

Basic question:
Does the PC-3 necessarily need any treatment? The instructions make it clear that the transformer bell will rust over time if not treated.
Is that true for any part of the PC-3 chokes as well?

Mine seem to have a coating of something (lacquer?) which might be enuf to keep them from deteriorating over time.

Even if that's true, I might still refinish them (without disassembly) because there are some big globs of lacquer which are aesthetically unpleasing.

John

 

[Paul Birkeland]

The PC-3 chokes are varnished as part of the manufacturing process.  You can lightly sand on any globs of varnish on the outside, but be sure to paint them if you do that just to be sure they remain protected.