Admiral 14R12 Restoration

[Kevin Kuehn]

Looks like you found the problem.

Can anybody explain to me why they reference the bottom of that doorknob to the plate of the damper? I know some of the older sets had it going to ground, so it was in parallel with the dag coating. So if the doorknob is leaking, there's effectively leakage between the HV and the 210V supply.

[Crist Rigott]

Originally Posted by old_coot88

If you want, you can run the big CRT without the doorknob temporarily, since the dag already provides a few hundred pf of capacitance. There'll be a slight voltage drop across the 1 meg resistor, probably not enough to notice.

I just might do that. I'd like to work on the alignment next.

[old_coot88]

Originally Posted by Kevin Kuehn

...Can anybody explain to me why they reference the bottom of that doorknob to the plate of the damper?

Seems like the only advantage is that the voltage across the doorknob is a bit lower (by the B+ value). But it shouldn't make any difference in the grand scheme of things.

I know some of the older sets had it going to ground, so it was in parallel with the dag coating.

In the old sets with metal bell CRTs, there was no dag system to filter the HV, so doorknobs served that purpose.

But when all-glass CRTs with inner & outer dag came along, doorknobs weren't strictly needed but were sorta "grandfathered" along by convention for a while. Seems like, anyhow. In the set being worked on here, the doorknob serves mostly as mechanical mount for the 1B3.

[Electronic M]

One way to further account for that grandfathering is that many makers used the same chassis to drive a wide variety of screen sizes, and for a while there was a mix of types (by screen size) available...IIRC one of the later metal tubes to be in use was the 24".

[Kevin Kuehn]

Originally Posted by old_coot88

Seems like the only advantage is that the voltage across the doorknob is a bit lower (by the B+ value). But it shouldn't make any difference in the grand scheme of things.

I was thinking the B+ also adds in series with the 1B3 rectified pulses, for a B+ boosted HV? Not sure it they were that hard up to get an extra 210v to the CRT anode, but it sure seems like the rectified flyback pulses are being stacked on top of the B+, relative to ground.

[old_coot88]

But the HV value itself isn't gonna change whether the filter cap is grounded to chassis or to B+. Remember, it's an RF ground either way (the spikes being filtered are RF).

With the cap grounded to B+, the DC across the cap will be lower by the B+ value. The HV itself willl be unchanged.

[dieseljeep]

Originally Posted by Electronic M

One way to further account for that grandfathering is that many makers used the same chassis to drive a wide variety of screen sizes, and for a while there was a mix of types (by screen size) available...IIRC one of the later metal tubes to be in use was the 24".

Rca built a 27" set, using the metal rectangular 27MP4 around 1954. IIRC, the rebuilt CRT was $66.00, with only a 6 month warrantee. There was also a 30BP4 available for $76.00, with the same 6 month warrantee.

[WISCOJIM]

Originally Posted by dieseljeep

There was also a 30BP4 available for $76.00

I could use a couple of those NOW!

.

[Eric H]

Originally Posted by dieseljeep

Rca built a 27" set, using the metal rectangular 27MP4 around 1954. IIRC, the rebuilt CRT was $66.00, with only a 6 month warrantee. There was also a 30BP4 available for $76.00, with the same 6 month warrantee.

That's probably why there are so few of those sets around today.

There was a 27" all glass tube in the later 50's, Magnavox made quite a few sets with them.

[old_coot88]

On the subject of doorknobs, plain filtering wasn't the only purpose they were used for. They were also used in doubler and tripler HV supplies, e.g., the projection sets of the late 40s, etc.

[Crist Rigott]

While I'm waiting for the door knob cap I thought I'd do a little cleaning up on the cabinet.

I washed it inside and out with some Dawn dish washing liquid and water using a small terry hand cloth.

Then I wanted to polish it up, right? Well I looked at different videos and so on and tried these products to get that high shine on this Bakelite cabinet.



I tried the Brasso, followed by the Gorhams followed by the wax and it didn't seem to help with the shine. I know the top layer is where you wnat to shine and I didn't go through that. Here is a picture of one side where I tried several products.



the largest circle was just using the wax, the next smallest was using Mothers and wax, and the smallest was using Gorhams and wax. In reality, not much difference between the three.

Here is a picture of the top. Yeah, it has a water stain. I tried Brasso, Gorhams, followed by 2 coats of wax. The finish is disappointing.





My big question is how much "elbow grease" does it take to shine this thing up? Am I not rubbing long enough? I usually go about a minute using medium light pressure with each product. Do I have to rub like 5-10 minutes on each section?

What am I missing? I do not want to use any sandpaper at all. I find it really hard to believe that I'm rubbing though the top layer.

Any ideas from those who have polished Bakelite to a high shine?

[bandersen]

Forget brasso. It has ammonia in it and can dull the bakelite. It's the old brasso in a metal can that works well. I've used novus #2 and simichrome with good results. Also Maguire's cleaner wax with contains a mild abrasive. Brown shoe polish or stain can help bring some color back to faded bakelite

[Crist Rigott]

Originally Posted by bandersen

Forget brasso. It has ammonia in it and can dull the bakelite. It's the old brasso in a metal can that works well. I've used novus #2 and simichrome with good results. Also Maguire's cleaner wax with contains a mild abrasive. Brown shoe polish or stain can help bring some color back to faded bakelite

Bob,
Did I do harm to the Bakelite using the wrong kind of Brasso?

OK, I'll stick with the Maguires.

Thanks.

[Kevin Kuehn]

I doubt the ammonia will harm anything once you cleaned it off with some other polish. Bakelite resins aren't easily dissolved, but years of sun exposure can really take it's toll. Too much sun slowly oxidizes away the surface resins, which then leaves the Bakelite filler material somewhat exposed on the surface, and that leaves a grainy wood like appearance.

[Crist Rigott]

Originally Posted by Kevin Kuehn

I doubt the ammonia will harm anything once you cleaned it off with some other polish. Bakelite resins aren't easily dissolved, but years of sun exposure can really take it's toll. Too much sun slowly oxidizes away the surface resins, which then leaves the Bakelite filler material somewhat exposed on the surface, and that leaves a grainy wood like appearance.

Here is a close up picture of what I'm up against. The nice area was behind the plastic bezel for the knobs on the front of the set. This one used the flash:


This one there was no flash:


Here is a general overview of that area:




Another close up:


I'm going to try a little Meguires on the bezel area. I'm guessing it'll shine up nice.