The PHILCO Phorum
Ron's RCA T7-5 Electronic Rescue - Printable Version

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RE: Ron's RCA T7-5 Electronic Rescue - EdHolland - 06-23-2018

Great work Ron! Nice to see your project come to life.

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-23-2018

Thanks Ed! Icon_biggrin

I've removed the knobs from their Evapo-Rust bath, and all of the spring clips inside the knobs are now clean save for the outer tuning knob; it could have benefited from an overnight soak but it will be OK. Evapo-Rust did not harm the Bakelite but it did dull the knobs; I shall have to polish them now.

Soaking the pieces of the ball bearing tuning mechanism removed eight decades of dirt, grime, and old grease. The two tiny ball bearings and the tiny spring came out from inside the assembly. I also removed the three larger ball bearings. All of the pieces are in a tiny zip bag; I will grease and reassemble all of it tomorrow.

The inner tuning shaft had quite a bit of rust where the knob pressed on to it, so it also received a good soaking in Evapo-Rust after its naptha bath. The rust is gone now! Icon_thumbup It looks clean and smooth. This Evapo-Rust is pretty amazing stuff.

I was finally able to remove the dial pointer - and without damaging it! Removing the dial scale is what did the trick. I never would have been able to get the pointer off otherwise. With no dial scale, I was able to get some PB Blaster at the very back of the pointer - which, as it turns out, is where it needed to be applied. Applying at the front of the pointer would never have had any effect. I can illustrate better with pictures, and if I don't forget, I will do that tomorrow as well.

This project is really coming together now. I will order a dial scale and appropriate decals from Radio Daze tomorrow, also.

RE: Ron's RCA T7-5 Electronic Rescue - Arran - 06-24-2018

I would have thought that a pair of 1N34 diodes would have been more costly then just picking up another 6H6 metal tube? The metal 6H6s, which are the original style, seem to be the most plentiful, followed by the GT style, I only have one radio that uses the ST style or 6H6G which is a Canadian Sparton.
Regards
Arran

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

I have plenty of 1N34A diodes here on hand, and it's an experiment I've been wanting to try.

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

Виктор, our cat, decided I needed to wake up at 7:45 this morning.

After breakfast, I went to the workbench and pulled out all of the parts for the ball bearing tuning assembly.

[Image: http://www.philcoradio.com/images/phorum/T7-5/T7-5_056.jpg]

White lithium grease is what I will use as the new lubricant for the tuning assembly.

It does not take long to reassemble, but you must be extremely careful and pay attention to what you are doing.

Here's how I did it:

First, I shot some grease through one of the ball bearing holes in the side of the outer tuning shaft. Not a lot, just enough to work down into the end of the shaft where the two small ball bearings and the spring will go.

I cleared out the ball bearing holes in the sides of the shaft enough to see what was going on in the middle.

I then carefully dropped the first small ball bearing into the shaft. I worked it down into the space in the very back of the shaft with the help of two small screwdrivers - one pushing in from the front of the shaft, and other used through one of the ball bearing holes to guide the little bearing into its "cave" deep within the shaft.

Next, I applied some more grease to the tiny spring and put it into the shaft, once again using two screwdrivers to ensure it went in properly. It must go in longways.

Then the other small ball bearing goes in. The procedure is the same as the first two parts.

Having grease in there already will do two things: it will hold the tiny parts in place, and it will provide much needed lubrication once everything is all together.

Next, I applied more grease into each of the three ball bearing holes as well as into the end of the shaft, and placed two of the three large ball bearings into two of the three holes in the side of the outer tuning shaft.

The inner tuning shaft is put in next. The rounded end goes in, the flatted end goes out. The inner tuning knob will attach to the flatted end.

While holding the two ball bearings you put into the outer shaft, carefully push the inner shaft into the outer shaft. Excess grease will flow out of the hole which does not yet have a ball bearing; this is what you want to happen. Leaving one hole empty allows excess grease to escape and prevents your losing one (or more) ball bearings.

Once the inner shaft is in the outer shaft, place the third and final large ball bearing in its hole in the outer shaft.

Now you must push the entire assembly into the "keeper". I find that it helps to hold the assembly upside down at this point with the inner shaft pressing against your workbench. Press down on the "keeper" and the whole thing will just go together, allowing you to reinstall the C clip on the end.

When finished, it looks like this:

[Image: http://www.philcoradio.com/images/phorum/T7-5/T7-5_057.jpg]

Wipe away excess grease, and apply some grease to the geared end. Now reinstall on the tuning condenser.

[Image: http://www.philcoradio.com/images/phorum/T7-5/T7-5_058.jpg]

That's it. The tuning is now very smooth with both inner and outer shafts, and the inner shaft will provide reliable fine tuning at any point on the dial as it should.

Since I am basically finished with my work under the chassis, I reattached the cross braces under the chassis.

[Image: http://www.philcoradio.com/images/phorum/T7-5/T7-5_061.jpg]

Yes, I still need to come up with a solution for reattaching the antenna Fahnestock clip to the chassis. I need to think about that some more. It works OK as is for now.

About that pointer...

The photo below will illustrate why the dial scale had to be removed before I could ever have any hope of removing the pointer. I partially reinstalled the pointer to help explain my point (no pun intended).

[Image: http://www.philcoradio.com/images/phorum/T7-5/T7-5_062.jpg]

There is a large cylindrical metal piece to which the pointer itself is fastened; this is a press fit into the tuning shaft. This piece is slotted. Since it probably has not been removed since 1935-36, and since this set was exposed to a lot of moisture at some point, the slotted piece had more or less welded itself to the tuning shaft with the help of rust.

Not knowing how the pointer was fastened to the tuning shaft while the dial scale was in place, I was applying PB Blaster to the center point (where the green arrow is pointing). That never would have done any good. The PB Blaster needed to be applied to the point where the red arrow is pointing. Once I removed the dial scale and began applying PB Blaster there, between that, some time, and the help of a powerful pair of needle-nose pliers applied to the slotted cylindrical piece (NOT the pointer itself!), the pointer assembly slowly loosened. Once I managed to get it partway out, prying in the gap with small flat-blade screwdrivers allowed me to remove it completely.

[Image: http://www.philcoradio.com/images/phorum/T7-5/T7-5_063.jpg]

RE: Ron's RCA T7-5 Electronic Rescue - Paul Philco322 - 06-24-2018

Glad to see the pointer came off, a true radio surgeon. 

You have a unique name for your cat, is it a nice name? Or not so nice?


Paul

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

Paul

Виктор = Viktor (Victor).

Icon_smile

RE: Ron's RCA T7-5 Electronic Rescue - NostalgiaRadioTime - 06-24-2018

Thanks for showing that dial pointer and what you went through to remove it. My congratulations on accomplishing a feat that I was unable to do Icon_lol Icon_clap

As far as that Fahnestock clip, I hate to sound like I'm crazy about pop rivets, but that's exactly how I attached a replacement one on a Philco a few years back. Of course you have to carefully bend the clip up to get your rivet gun under it, but it can be done. It's works well on the antenna clips, where you have the fiber washer underneath the clip between the clip and the chassis to sandwich in.

Oh and you may want to remove and spray paint the back plate behind the dial a nice bright shiny white color. It will make the new dial really "pop" with the reflection from the light.

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

Thanks, Greg, for the suggestions. I've ordered the new dial scale; it takes a few weeks for Radio Daze to fill orders for dial scales so I have plenty of time to remove and paint that back plate as you suggested.

Attaching the antenna Fahnestock clip back to the chassis isn't going to be easy. There was a "sandwich" of two pieces of phenolic. The antenna clip was riveted to the outer piece. Then there was an inner piece to insulate that from the chassis. Both pieces were riveted to the chassis. The antenna lead comes through a hole in the chassis to the left of the two pieces of phenolic. (Yes, I should take a photo to better illustrate this.) Both pieces of phenolic are broken where the clip originally was fastened. If I used pop rivets, I would have to drill an extra hole in the back phenolic piece, and through the chassis, to keep the pop rivet from grounding the antenna to the chassis. Or, perhaps I could pop rivet the clip to one piece of phenolic and then grind it off to the point that there is only a tiny amount of space between the sheets of phenolic? I wonder if the pop rivet would hold if ground down? Hmmm... Icon_think

RE: Ron's RCA T7-5 Electronic Rescue - NostalgiaRadioTime - 06-24-2018

I took a peek in the back of my T7-5 and see what you mean. I remembered the Philco I did that to and believe it only had one washer between the clip and the chassis.

You could experiment with grinding down a rivet on a scrap piece of metal to see how well it will hold. I would think once the rivet is mushroomed in place, even without some of the head it should still hold. This is only a thought, however. I've never personally tried it.

Or perhaps you could add a small fiber washer between the two pieces of phenolic so that the rivet head would fit in the hole of the washer. That would act as a spacer to prevent the rivet head from grounding out against the chassis.

Easier said than done, I know, as I only had to deal with just the one broken clip and it was on a Philco.

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

Well, as I said...I will think about it some more before I decide upon a plan of action for the antenna Fahnestock clip. Oh, and the clip on mine is OK, it's just the phenolic it was attached to that is broken.

The Philco sets use two pieces of phenolic as well, but they fit into a large hole in the chassis and each half is "stepped" so it fits snugly into the large hole. Once riveted, the pieces hold themselves in place tightly in that large hole. And the antenna lead is soldered to a solder terminal on the inside of the chassis where the Fahnestock clip attached on the outside. The rivet acts as a conductor for the antenna.

I tried to paint the dial back plate this afternoon. It was a disaster. It fisheyed horribly. I guess I will strip it down and try again, but not tonight. I will wait until I can find some better spray paint (the only light color paint we had here was some Wal-Mart cheapie spray paint) and some primer. I will strip it down to bare metal before trying again, rather than rubbing down the original ivory paint with 0000 steel wool and painting over it as I did.

Painting the dial pointer went well, and it is now put away in a safe place to wait until the new dial scale arrives.

RE: Ron's RCA T7-5 Electronic Rescue - NostalgiaRadioTime - 06-24-2018

Ah, I should have looked back at the photos...for some reason I thought the actual metal clip itself was broken off but that the phenolic was intact. Now I see the missing part of phenolic.

Yes that RCA clip is altogether different from the familiar Philco one's. I remember now the two phenolic discs on the Philco I did. Riveting wasn't a problem, though, as I recall.

Hopefully you can find a scrap piece of phenolic to use.

I ran in to similar problems with painting. Very frustrating to watch the paint fisheye on you. Once I started to use primer first that rarely happened. From past experience, I'd recommend the light grey colored primer if you're going to paint white over it, as the brown may bleed through.

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

I already had light gray primer in mind... Icon_smile

Received an email from Rich Stamer at Sound Remedy in response to my inquiry about reconing the speaker. He said to send it on in to him, so I will find a suitable box, remove the speaker and pack it up, and send it to NJ later this week. Icon_thumbup

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 06-24-2018

(06-23-2018, 05:59 PM)Steve Davis Wrote:  When I was young, we had the console version of this radio.

The console version was the C7-6. There was also a six tube console from the same model year (1936) with, I believe, the same dial.

I was just looking at a C7-6 thread on the other forum. Was burned spots a common thing on these dials? That chassis has a burned spot on its dial, as mine did. Mine now has an LED dial lamp so heat will no longer be an issue.

RE: Ron's RCA T7-5 Electronic Rescue - Ron Ramirez - 07-02-2018

No one commented about the burn marks on these dials, so let's move on.

I have primed and painted the dial back plate. As it turns out I had some gray primer on hand, so between that and the cheapie Wal-Mart white paint it looks good now. Not perfect but good.

And speaking of dials, the new dial scale for this radio should be here in a few days. Rich at Sound Remedy has the speaker. I will need to get the cabinet repaired and refinished now. And I still don't know what kind of grille cloth I should use, since the original wheat stalk pattern was never reproduced.