Hi Brook. It's nice to know I'm not the only one taking on a porthole as a first project.

I asked another ARF porthole member this question but I'll ask you guys too. The drop down metal door in fron that covers the controls--there's a shield/insignia on the top center of the door. Is the shield background painted red? Anybody care to post a pic of that so I can mke sure mine's right?
Thanks,
Ben

Why are you replacing resistors on hv rect.?
Don't use metal film. It will arc.
Most of the modern resistors can't take that high a voltage....
Bill Cahill

Bill,
I can understand the metal film arcing but doesn't the ability to handle voltage relate to the wattage of the resistor? Can carbon comp resistors handle HV better?
Ben

Not to the best of my knowledge. Carbon comp may be fine.
Bill Cahill

Got the flyback coated with the winding dope. It penetrated pretty good and dried flexible. Temperature rated for 600F so I'm not worried about that. I let it dry over night and this morning started applying the sensor safe RTV as recommend by Phil. I used a wood coffee stirrer. I'll be confirming the winding resistances again after work today.

That certainly is RED! How did you get the goop off?

Goop? That must be a tech term I've never heard of
I decided to go with red because it matched the sofa...these are real bad jokes..sorry..
There's a pic of the wax that was on there earlier in this thread. It looked pretty sad. I heated it with a blow drier and carefully scraped it off.

Back at it.
I decided to take the advise of the pros and not shotgun replace all of the resistors. What was I thinking? Once I took a long look at the underside of the chassis I realized it would take a good part of the rest of my life to do it. Also, many of the resistors in the schematic allow for a 20% tolerance. Some of the others are rated at 10% and I'll deal with those on a case by case basis. I'll just check as I go.

First up were R77 and R80. The R77-- a 407k --was a litle high at 502k, but represented less than 7% drift up. I'll keep it. The R80 checked spot on at 3.3 ohms.

I replaced my first cap, C71 .047mf with a .05.

I carefully inspected the home for the flyback, cleaned the plastic sheild that surrounds the 1B3GT socket and fixed a terminal in the socket that had slipped out due to heat from soldering. The plastic shield was still supple after all these years. I hope I fare that well..
,

Next Monday I'm taking a copy of the schematic I got from an ARF member, Kevin, and getting it enlarged to 36" x 24" so I can stick it on my wall and track progress. It's costing less than $5-- not bad. All the good resistors that get checked and are within specs get highlighted in green. I can also note their value and take other notes as well since I have the space. Caps that get replaced are highlighted in yellow.

Since this is the biggest restoration I've taken on, I'm going to be organized and take on one section at a time, replacing any parts needed and checking the specs to make sure it's right. Then I mark it off on the schematic. I can also double check wiring and highlight that as I go too.

I'll also be taking lots of pics and I definitely appreciate any comments, observations and stories.
Ben

Here's one of the mechanical parts I'm going to tighten up. I pulled it this afternoon and discovered the pinion gear is integral to the drum and can't be removed. There is a lot of slop between the backing plate and drum, which caused the numbers to wear off on the outside, as shown earlier in the thread. I pulled the main gear and gave the drum a good cleaning in warm water and dish soap. The plastic gear on the inside of the drum had a few bumps and so I carefully scraped the teeth until the pinion rode smoothly over it. I also scraped all of the black gunk out of the teeth.

What I'll have to do is take the drum into my local hobby shop and find some brass shim material that fits between the drum and back plate to keep the drum from wobbling--which is what wore off the numbers. If you look closely, one of the three white struts that sits at the back of the drum broke off as well. If I'm feeling very ocd I'll put a new one in.

Once everything is right with the drum I was thinking of making a decal of the numbers in Photoshop, re-smoothing the outer diameter of the drum, applying the decal and coating with acrylic sealer.

I'm impressed with the work you are doing. Keep it up.
Your organization you mentioned in an earlier post will make the work easier.

That porthole you have has a real classical look and is worthy of the effort you are putting into it.

Carl

I just finished reading all five pages of this thread and have learned a lot. I'm a rank amateur at this
and am at the very early stages with my Zenith 24H21 H2445R. Thanks noisebox and CW. I'm off to kinkos
to enlarge some of the parts lists, especially the electrolytics we'll replace come May. That flyback
mess is something else. Hope I don't have to go through all that!

You're doing good meticulous work.
Doing the up front stuff like getting your diagrams organized will be very helpful all during the restoration.

During my Porthole restoration, I kept a picture book of the process:
http://www.cerant.com/ZenithPortholeTV/

Carl

Carl, I'm enjoying reading the thread from your "Cinderella" restoration! I'm on page 16. It's going to save me a lot of time and trouble because now I know where some of the problem areas can lie and can be prepared.

A few questions to you or any lurkers:

• The test picture tube-- is it necessary? Should I look for a round one?
• The ceramic encapsulated tube capacitors--all of the charts I've found have the first color as the temperature coefficient. This doesn't seem to jibe with the first cap I replaced. The colors were Y=4, V=7, O=1,000, Black=20% tolerance. I thought the red stripe at the end was the temp coefficient. Also--I heard mention of the voltage ratings expressed as a color. I'd hate to use a cap with not high enough voltage rating. On the schematic I can see where some of the caps have a tolerance rating--they appear to be in the IF section and they have smaller values so I'm assuming they're the ceramic or domino caps.
Thanks,
Ben

I would recommend a test picture tube. On mine, I purchased a rectangular 8" 8XP4 and later a round 5" 5AXP4. The 8XP4 was the least expensive and worked well.
The reason I would is that is you want to protect the large CRT and not accidentally damage it when you have to turn your chassis over.

I also found making a stand for the chassis was helpful.

YVO should be 0.047uf. I forget the voltage rating colors.
I usually leave the disc and rectangular ceramic along.
I do replace all Paper, Bumble Bee, and Electrolytics on the first pass at recapping.
I would leave the small value capacitors along and deal with them after you power the TV.

Carl

Any idea where I can find a test tube? Cost?
I have the original safely packed away for the reason you mentioned.
I also like your idea of a stand because I'd hate to crush and bend anything important. Looks like it made the recap and other work a lot easier.

The caps, I always do the electrolytics and paper etc in all of my projects before I fire it up. I find the mix of bumble bees, ceramic tubular, ceramic and domino caps interesting in the porthole.

I'll be matching the values of the caps against the schematic as I go along but the voltages don't seem to be marked on the schematic--unless I'm missing them. Any pros out there who might know where the HV caps traditionally reside?

BTW, I'm going to be careful in removing the bumble bees and put them up on ebay. Have you seen the $ some are willing to pay for them?
Ben

The capacitor voltage ratings use the same colors as the value and multiplier numbers, so red would be a 200V capacitor. I just put 600V caps in anywhere the original had a 600V or less rating.

To find a 5AXP4 or 8XP4 test CRT, just keep watching Ebay and the ad section here, or even do a Google search and see what comes up. I found my 5AXP4 on a site that had a long list of various tubes for sale a few years ago.

Some of those "domino" caps Zenith used are actually resistors, and, usually good.
Bill Cahill

As a heads up, I found my 5AXP4 test CRT on Ebay.

But, I found my 8XP4 test CRT by placing a WTB (Want to Buy) post in ARF's Classified.

Carl

I did a little cleaning of the chassis this morning before work and decided to open up the power transformer. It's nice that both bells come off so I can paint them without having to pull the whole thing. The protective heavy paper looks a lot like it could hold a full order of French fries to go When I removed it the leads looked real pretty, like an exotic flower. I know--that's not a guy thing to say but it was surprising how perfect it looked as well as the colors of the leads.

Tomorrow morning I'll be replacing the flyback, building a rack mount like Carl's and starting in on the recap. Two of the electrolytic cans are a little tucked in there but I'll be getting the values and ordering them as well as some other misc parts.

After poking around the chassis a little this morning I realized how fortunate I am with the condition of this TV. I used a little Brasso and a green pad and rubbed out a section of the chassis and it looks very nice. I was reading some of Carl's thread and got a chuckle out of him being teased about making things look pretty before he fired it up. I guess I'm from the same school of thought--I polished the fuse clip (and the fuse!) with my Dremel this morning until it looked like a piece of jewlery I feel like an Audiophool--"it sounds so much better when the contacts are polished...."