800B Dial Cord

[Joseph W Strickland]

I made an interesting discovery today while cleaning the backside of the metal that the black part of the dial is attached to.  I was cleaning the metal surface with some chrome polish to remove some light rust that had developed there.  When I was wiping away the residue of the chrome polish, I discovered that the dial cord on the 800B seems to consist of copper plated braided wire!  E H Scott was not satisfied to use conventional fiber dial cord material. No wonder that the dial cord is still just as tight as it was when new.

There was considerable dust and dried grease around the pivot points and brackets that the manual tuning shaft passes through. Some lighter fluid and Q-tips removed the dried up grease and then some more chrome polish provided some extra clean-up of those parts. I used the chrome polish also on the tuning shaft to the 3-gang tuning capacitor to remove some oxidation. It came out looking much better.  All the metal toward the front of the radio tuner chassis will get extra cleaning to remove corrosion. Then will come cleaning and lubrication of the pushbutton switches and their mounting brackets. The eye tube support brackets will get cleaned too.

I learned that there is a chrome plating operation the next county to the west of me. I am thinking about visiting the shop and talking to the owner about removing the existing plating on a spare chassis I have and rebuilding it. All parts will have to be removed from the chassis before it can be stripped down and rust pits polished away and then re-plated. It will be quite time consuming and also expensive I am sure. I just need to get a ball-park idea of what it will cost to re-plate the radio tuner chassis.

Joe

[Norman S Braithwaite]

Joe:

The cost of chrome service will depend on the condition of the chassis to be replated as well as local labor and environmental conditions.  Generally, the cost of replating old steel will cost about twice the cost of plating virgin steel.  I have  been paying approximately $200 to $250 for replating large chassis (Scott tuner chassis).  More importantly, you will need to make sure the plating service understands that the chrome on the under side of the chassis must stick (not peel) or that the under side of the chassis not be plated.  Additionally, the chassis should be rotated during the sanding and polishing operation to avoid drawing the holes.

Norman

[Joseph W Strickland]

Norman;

Thanks very much for those pointers on re-plating. I would imagine that they could use a wax on the underside of the chassis to keep from plating that area or else do as you said about making plating stick well on the underside as well as the top.

When you reassemble, how have you dealt with getting good grounds for the long term? I know that dealing with dissimilar metals can lead to electrolysis and corrosion, ultimately developing poor ground connections. Do you use rivets to remount tube sockets and other items that have to have a good ground or some other method such as screws, star washers and nuts? If I am going to go to that much effort, expense and time I want to do it right.

Joe

[Norman S Braithwaite]

Adding a bottom plate to the chassis will prevent the chrome from plating under the chassis.  Unless using hexavalent chrome which I believe is no longer available, chrome does not like to plate in corners and tight spaces.  I don't worry about ground connections on rechromed chassis.  So long as the chassis is kept in a dry environment, the connections should be good for at least 50-years at which time it is exceedingly unlikely that I will be worried about such things.  I do use rivets where rivets they were originally used.  Where EH Scott Radio Laboratories used rivets for ground returns, they used a star washer between the lug and the chassis.  If concerned, use machine screws.  They can be loosened and retightened if a ground return develops resistance.  I know of collectors who turned the heads of stainless steel machine screws to look like rivet heads and used the "fake" rivets for reassembly.

[Joseph W Strickland]

Norman;

So is it possible to use the bottom plate that came with the radio and power supply chassis to prevent plating on the underside? Or is a custom bottom plate needed for the process?

Stainless steel screws would definitely be a long lasting fastener to use, although if stainless steel nuts are also used they can be almost impossible to remove, if that were ever desired. It can gall the threads and have to be ground off in order to remove them. That may not be true for all formulations of stainless steel though. I would have to check with one of my mechanical engineer friends.

Today is a beautiful day to work outside. That is what I have been doing. We had a recent frost and now the tree leaves are turning beautiful colors.

Have fun!

Joe

[Norman S Braithwaite]

The original bottom plates for the 800B overlap the chassis sides at the bottom of the tuner and amplifier chassis. Use of the original bottom plates will prevent plating where the sides are covered by the bottom plate. It would be better to make bottom covers out of thin sheet metal (not aluminum). Ask the plating service first.

Norman

[Joseph W Strickland]

Norman;

I noticed that the bottom plates that came with them wrapped over the lower part of the sides of the two chassis. It will have to be some sort of custom plate as you said. I need to ask about what kind of metal would be acceptable for making such a cover.

I remember a previous discussion you commented about - the wired remote control option that was available for the 800B. I was looking at the volume control on my early 800B and the back side of that control is open, You can see a plated thin metal structure that is attached to the control shaft and also to the piece of bakelite that moves with the rotation of the control shaft. RCA used a similar arrangement on some of their tube type color TV sets in the mid 1950s and into the 1960s. They had 6.3VAC small drive motors attached to the mating pieces in the controls. By such motors (which had a gear train built into them) the customer could cause adjustment of volume up-down-power on-off, color intensity up-down, tint or hue change. These were activated by tuned circuits and relays in an ultrasonic transmitter/receiver arrangement. The customer had an ultrasonic hand transmitter and the set hat an electrostatic transducer used as a microphone. The same transducer was used in the hand transmitter along with a single transistor oscillator that drove the transducer. The downside of the system was that keys and pocket change sometimes caused one of the functions of the TV receiver to activate. The receiver circuits of the early ones had vacuum tube tuned circuits associated with each function driving relays that sent the 6.3VAC to the drive motors. The manufacturer of the motors was Lionel of the model train industry. It would be neat to have something like this for the 800B models. Of course the remote chassis would have to be chrome plated too in keeping with the rest of the unit. It sure would be nice if I could find one of those old color TV sets equipped with the remote control circuits. Ahh such dreams!

Joe

[Norman S Braithwaite]

Discuss options to prevent plating under the chassis with the plating service.  Different services have different preferences for preventing plating where not wanted.

Norman

[Joseph W Strickland]

Norman;

Good point. I need to put together a list of issues and questions to discuss with the plater when I go to his shop. It will be interesting to tour the shop and see some of the process if that is possible. When I worked at Collins Radio, we had our own plating shop in house. Most of the chassis were plated with chromate, either a silver finish or a gold colored finish. Some other items were nickel plated, but not chrome plated. Annodizing was also done. I never did meet any of the employees that worked in that area.

Have a great day!

Joe