[RodB]

Yes, you can wipe naval jelly with a damp cloth then with a dry cloth. Looks like you have some bad spots, leave the jelly on for a couple hours or more keeping the spots wet with the jelly. If you don't like the dark spot that remains treat them with a metallic rustoleum paint. Spray into a plastic cup then use a brush.

[Arran]

Joseph;
I don't think that it makes much difference when it comes to thick, crusty rust, it's going to take more then one application of either a wad soaked in vinegar, citric acid, or Navel Jelly to get it all off. I once had a chassis so bad that I resorted to using muriatic acid (HCl) on the rust, it worked somewhat faster but not better then vinegar, then there are the fumes, in the end I stripped all of the parts off the top of the chassis, drilled out the tube sockets, (I did not remove them, just pushed them down) and took a wire wheel to it with an angle grinder.
Regards
Arran

[klondike98]

Joseph, we could keep your digital schematic versions in our digital library if you want and are willing to have us do that. That way they would be available to all who want to down load them. Let me know.

[jrblasde]

Certainly, that'd be an excellent idea! Tell you what, let me PM you a fresh copy of those files. I was recently looking back on my schematic for the 46-480 because I have a similar IF design here on this 47-1230, and I realized that I had a typo (I accidentally labeled both Z301 and Z302 as Z301). I'll fix it right quick!

EDIT: Correction, I looked back, and my 46-480 schematic was okay. For some reason when I added that block to my KiCAD library, the default identifier was Z301, but my schematic for the 46-480 had it correctly identified as Z302. I've instead fixed the block in my KiCAD library, for future implementation.

[jrblasde]

On to this last week's progress. Admittedly, not much got done; work was so busy so that I even had a couple of 13-hour days! But that's over with now. 

Being that there's no electronics which wold be ruined on that bottom plate which was so rusted, I was able to soak it for about five days in vinegar. I had great success in getting it cleaned up! After the rust removal, I disinfected it. It's looking better! There's definitely a lot of pitting, but I don't mind it since this will face the inside of the chassis.

   

   

I also picked up some stronger 6% cleaning vinegar today while at the store. Since I can't soak the chassis without having to gut it, I'm hoping that this stronger vinegar will prove more effective with the soaked-rag-placed-onto-the-rust method. If not, I'll go to naval jelly route.

[RodB]

You might want to spray some paint on that bottom plate to slow down any corrosion.

[MrFixr55]

Is that pattern from the vinegar or is it original?.

A great rust remover (albeit, really strong) is muriatic acid, available from the hardware store. While there buy protective goggles and glove.

Start by diluting it 1 part of acid in 5 parts of water, adding acid to the water. This will give you 2N HCl. If insufficient, add 1 part of acid to 3 parts of water (3N HCL). If still not enough, 1 part acid to 1 part of water, and pour slowly. This is 6N HCL which will definitely remove rust.

Have a strong Sodium Bicarbonate solution to neutralize the acid and have something to put on the chassis to prevent rust.

I am going to try to paint the RCA T7-5 chassis. I think that the Philco 37-116 will clean up well enough, and will protect that with either a light coating of oil or Armor-All.

[jrblasde]

I've been meaning to reply to you, Mr Fixr, but it's been a busy week! No, that pattern is not original. I believe it came from the plastic bag I used to soak it in vinegar; probably just some ripples from the bag were transposed onto the metal.

Great idea to use paint! I think I'll give the paint a try on the inside of this piece of metal (the inside facing portion was the badly damaged part). It's not being used as a connection to chassis ground for anything, so I don't need to worry about blocking any rivets or other connections from bonding. I already treated the underside by polishing it with WD-40, so hopefully that provides some moisture protection.

I've also been speaking over PM with Bob, about sharing all the computerized schematics that I've made for my various restorations. I'm happy to do it, but we've talked and decided that I will first convert them to the newer 11" x 17", multi-page format that I used for this 47-1230 schematic. It makes them more neat and readable, and people can more easily get access to an 11" x 17" printer than they can a plotter for the old E-sized schematics. I'm about halfway done converting my 46-480 schematic, and then I'll do the 48-482 schematic. After I finish cleaning up the chassis on this 47-1230, I'll compare my schematic against it to flush out any inconsistencies between it and the original Philco schematic from which I produced mine. Then we'll upload that one! Work has been busy again this week; I've had some more long days, leaving little time to get this done. The busy spell should (for real, this time!) be over now, but this morning I am leaving for a trip and will be out of town until next Wednesday. So that will put a damper on things until next Wednesday. At this point I'm hopeful to get those all converted and turned over by early September! I'm optimistic that I can do it.

[jrblasde]

Despite my lack of posts lately, I’ve been working in the background on cleaning this nasty chassis! I think I’ve made it through about 3/4 of the cleanup. 

Regular 5% “eating” vinegar simply wasn’t cutting through the rust very well, so I bought some 6% cleaning vinegar. That 1% makes a big difference! In fact, it’s a 20% (relative) increase in concentration. It’ll burn any cuts on your hands, too! But finally I have found something strong enough to eat the rust. I’ve been soaking cotton balls in the vinegar, squeezing out the excess, and applying them to the rust. I let it soak for half a day or so, and then scrub the area with a toothbrush. Oftentimes I have needed to repeat this four or five times on the same spot, but it’s working! Here’s my current progress.

   

   

   

   

I’ve gotten the larger areas cleaned up. Right now I have the power transformer dismounted, and I’m cleaning the chassis around it. I still have to clean around a few tube sockets, but that will come next. I also need to remove the two electrolytic capacitors to clean the area around them. But the most serious rust has already been dealt with, and that’s great!

I’ve read that you can apply a protective coating of microcrystalline wax over the chassis once it’s been cleaned. In doing so, it will look original (unpainted, that is) but will be protected from further rust. I may give that a go! I’m also going to strip and repaint the bells of the transformer, and will use a brass wire wheel to clean the rust from the core.

[radiorich]

Hello joseph,
What I tried on the chassis I’m restoring was a recommendation from one of the radio guys on the ARF Forum—to coat it with Howard’s Feed N Wax afterwards.

Sincerely Richard

[MrFixr55]

One problem that you will have is getting the endbell with the wires passing through off. Either work with it on the transformer or cut the opening of the endbell into a "U" shape to remove. This will keep you from having to unsolder all of those wires to remove the endbell.

Vinegar is 5% acetic acid. If you can get a hold of "glacial acetic acid", this may work better.

I have had good luck with Naval Jelly for cleaning rust. If you are brave, you can also use dilute muriatic acid (12N HCl) Dilute it one part acid to 11 parts of water to make 1 N HCl. If you want to be braver, dilute 1 part of acid to 3 parts of water to make 3N HCl. PLEASE, ALWAYS wear protective goggles or better yet a face shield, appropriate gloves and waterproof apron and always add the acid to water slowly, never the other way around. Do this in an open space.

Tape off the sockets and keep any of this stuff (Acid, vinegar, naval jelly, etc. ) away from any socket contacts, etc.

Good luck with your project!!

[jrblasde]

Thanks for the recommendation, Rich! I was wondering what brand to use.

And thank you, Mr. Fixr! I guess I’ll have to take a look at the bell and the cables. I had noticed that the one bell was trapped by the cables but I started to think that I may need to unsolder the leads in any event, if any of the insulation should be crumbling. But I like your idea. I could very easily mask off the rest of the transformer and chassis, and refinish the bell in place.

[Arran]

Joseph;
I'm happy to hear that you have also had some success with the vinegar wad method. I guess that cleaning vinegar comes in different strengths, the stuff I found at Canadian Tire was 10% Acetic acid, or 30% if you wanted a more concentrated version. The regular kind is only 5% same as what you encountered, I think I got it to work mostly because the rust wasn't quite as heavy, that or it I left the paper wads on longer. I thing that vinegar is the way to go, it's inexpensive, and it's safe, muriatic acid is basically HCl and whilst it will strip rust off quickly it will also cause it to reappear, it's also really hard on aluminum, and will destroy some plastics. I suppose you could dilute it, but then again vinegar doesn't involve the same handling hazards. If you want to stop the rust coming back phosphoric acid works as a rust inhibiter, some hardware stores sell it as a cleaning product to remove lime scale from water filters and plumbing, it's one of the ingredients in Navel Jelly, but it doesn't really work that well by itself as a rust remover.
I can see the issue with getting one of the end bells off of the transformer, it's funny because many transformers of that style just have the bells go all the way down to the chassis without the hole.
Regards
Arran

[MrFixr55]

I was thinking about phosphoric acid, it is used to etch metal before painting. It may also convert rust. It may be a component of spray rust reformer paint. You may be able to get that from any auto parts store that has a large bodywork supply department.

[jrblasde]

Rich, I picked up some of that Howard Feed n Wax after work today. It’ll probably be another week before the chassis is cleaned up to the point that I can start waxing, but I’ll give it a go!