My dad does cad plating.. Billmark. 817-834-2481..

Looks like cadmium plating from what I've read--yellowish oxidation. Carl, I think it would be next to impossible to remove it. No reason to either since it's all in very good shape. As you can see in the pic there's a lot of grime, but the metal looks nice under it. I've been using a green scrubber and WD40. One of the reasons they used cadmium is its resistance to corrosion and it's solderability. There are some pretty big braided grounds soldered on top. You can see one dangling from the center in this pic.

A nice cleaning tool I discovered. I cut a small disk out of either a green scrubber or this more coarse brown one and stick it on the mandrel of my Dremel. It doesn't have to be perfectly centered since it seems to self center after a few spins. I learned the hard way to keep the speed slow--it dove over an edge and grabbed a wire and yanked it At slow speeds it polishes delicate parts very nicely. Shown below that is the IF section cleaned up a bit.

This is where I get into trouble sometimes. I began to take off cover plates "just to see what it looks like," and got deeper and deeper into the mechanism until I had no choice but to clean it up and put it back together. The tuner drum was calling to me. I can hear some of you saying, "No! don't touch that!" But it was too late--I had to see how it worked....

First I'll give you a spoiler and show you what it looks like put back together and all clean. Then I'll post pics of the process..

This is what I learned about the channel strips. The contacts were obviously dirty and needed cleaning up. I used my Dremel scrubber and cleaned the contacts. Then I ran some warm water with dish soap and used a soft artists brush on the circuit reverse side. I dried them with my heat gun on a low setting. After they were dry I shot them with a little DeOxit to keep them good.

Each strip was numbered and had a coresponding number on the drum. I made sure of that before I took it apart

The bottom pic shows the underside of the tuner circuits. The tabs on the channel strips slide between the half moon contacts when the drum is rotated. I slid some very fine wet dry sandpaper between them and a shot of DeOxit to top it off.

I don't know enough about the circuits but I'm guessing each strip has a tuned circuit that is specific to the frequency of each channel..

Here's the drum assembly taken apart. Notice the front ball bearings. They fall out when the retainer is taken off Fortunately, they were covered in old sticky grease and didn't go far. There was also a larger ball bearing at the rear of the drum, which ended up down my kitchen drain. I knew this when I turned on the garbage disposal The hardware store had one that worked and so I am redeemed--this time! The gear required a little heat to be able to get the frozen retainer screws out.

The second pic shows the rear of the assembly with the mechanism that sets the position of the drum for each channel. It's basically a steel ball in a socket retained by spring steel. You can see at the back of the drum how the ball rides the hills and valleys, holding fast in the valley until the selector is turned. Personally, I think they overbuilt this--just a little.

In the third pic you see the numbers on the back of the drum to designate the channel positions. The set screw in the center holds the drum shaft at the proper tension. The blue goo you see is Locktite. I'd hate to have to take it apart a second time. There was a little play on the spring bolt holes to enable positioning of the drum, insuring the contacts on the strips were in the right place at the right time.

Hello Noise,
you sound like me I seem to get myself in trouble sometimes going to far

As they say Rich--curiosity killed the cat--and getting everything back together brings him back

Bet you wear the shirt with the words "No Fear"

That is a nice job cleaning up that Chassis.
My last restoration I sprayed on a cleaner and hosed itt off with a garden hose -- but don't do this until you protect/remove parts that would be damaged by water. Still, you don't need to do this. Yours is clean.

Get some contact cleaner like Deoxit and spray the tuner contacts and rotate the channel knob so the cleaner is spread across the contacts surface.
Do also to all your control pots so they won't act scratchy.

Carl

Here's some views with the assembly put back in the chassis. The brown knob on the shaft with the spring shaft is a built in "wrench" that extends into the tuner drum to adjust each channel strip. I don't know why, but I think that's a funny thing to build in. I also think it would have been nice to build the adjusters into the back end, away from the CRT HV.

I was also able to line up the fine tuning pulleys. I had found a rubber belt that was broken and assumed that's where it came from. However, I discovered in another porthole thread on ARF that it should be a dial cord with a limit at each end. Now I have to find my stash of dial cord and a spring.

I still have a few days until my caps get here so I'll finish cleaning the chassis top and get familiar with the underside better. I'm also finishing the disassembly of the cabinet.

Carl,
I'm either wearing "No Fear" or 'Too Dumb To Know Better." It depends on the day.

DeOxit has been my friend on this. I broke down and got the expensive spray can. I've already gone over all of the tube sockets, contacts and pots. I think I'm going to have to replace the volume/switch pot. The shaft was broken and cobbled back together and the switch has lost some of it's snap. I'm going to contact Mark Oppat and see if he has one that's close to the original.

On my Porthole, I had to replace all 5 front-panel POTS - but mine were heavily rusty.
Yours probably should be ok except for the one you mentioned.

The designers must have had disrespect to repair folks when they put that "Bulls Eye" tuning know so close to the HV on the CRT. Imagine a repairman having to stick his hand in a dark live cabinet and adjust that knob while simultaneously using a mirror to see how the picture is changing.

I aligned all my channels when I had a small test CRT installed - so I would not be shocked. But, still I had to do some fine adjustments with the Metal CRT installed - but only with the chassis out of the cabinet.

Carl

I'm going to need some big help once I get to the point of firing it up. What kind of adjustments should I be expecting? I make it a point not to mess with any of the IF's and other adjustments when I'm on my cleaning expeditions.

Hello Noise Can't wait to see you fire this baby up and when you do try to keep the smoke in the wire as my electronics teacher would say about the locus wiring in english cares

Hey--I found this info and was woondering if this was something I should be considering---

Additional Information on Discharging CRTs
You may hear that it is only safe to discharge from the Ultor to the Dag. So, what the @#$% are they talking about? .
BTW, don't wash your CRTs even if the Maid complains about the filth until you have confirmed that your 'Dag isn't water soluble (maybe that's why it has 'aqua' in the name!). It may all come off! Wipe off the dirt and dust with a cloth (and stay away from the HV connector or make sure it is discharged first!).

'Dag' is short for Aquadag. It is a type of paint made of a graphite pigment which is conductive. It is painted onto the inside and outside of picture tubes to form the 2 plates of a high voltage filter capacitor using the glass in between as dielectric. This capacitor is between .005uF and .01uF in value. This seems like very little capacity but it can store a substantial charge with 25,000 volts applied.

The outside "dag" is always connected to the circuit chassis ground via a series of springs, clips, and wires around the picture tube. The high voltage or "Ultor" terminal must be discharged to chassis ground before working on the circuit especially with older TV's which didn't use a voltage divider to derive the focus potential or newer TV's with a defective open divider.

Your tube doesn't use the dag coating. The metal bell is the second anode.
On the dag therory for glass tubes, I sued chassis ground for initial discharges.
As a last resort, after I dis connect second anode, I sometimes discharge it to coating to discharge anything remainning in tube as well.
But, that's rarely needed, once you properly discharge hv.
Metal tubes don't use ground coating.
Bill Cahill

Since I'm on the subject--discharging the Zenith CRT-- would that be from the outside of the CRT to the top of the chassis or the bottom--or does it matter?

Top, or, bottom????
Just discharge it to chassis.
But, if you haven't plugged set in, why are you worried about hv at this point?
Bill Cahill

In your set it is that doorknob capacitor that holds the high voltage charge. In sets with glass CRTs with a coating on both the inside and outside, the coatings and the glass form the necessary capacitor. Some early sets with glass CRTs also had a doorknob capacitor, but it only took a few years for the engineers to realize that a doorknob capacitor was not needed with a glass CRT.

Depending on how clean everything is, the doorknob capacitor can hold a charge for as long as several days. With enough dirt over everything it will discharge much sooner. But if the set has been off for years, you do not have to worry about getting zapped until after you have powered up the set.