Thank you! I had the fire extinguisher ready for the first power on.

I guess the RF modulator I was using wasn't strong enough. I pulled out my Agile Modulator and am able to get a usable signal at least. Color off and its not too bad, but color on even a little bit and its rough. All images are channel 4. With the agile modulator, I was able to broadcast on UHF; picture is a little bit cleaner, but more or less the same.

I was able to sort out the fine tuning of the channels and the last image is the best I was able to get. Still not great. This is also with the focus adjustment maxed out. My kit came with a 4.7 megaohm resistor if the focus can't be adjust enough, but that was for a different set. Not sure if it is applicable here.

Very good! Now you have a good sense of where you are at! Turn the color off and work toward the best B/W picture you can achieve. Nothing is going to look right with the set on its side. I would concentrate on solving the snapping every 10 seconds. It wouldn't hurt to clean in the inside of the set. I usually use a vacuum with a small paint brush and work gently through the chassis. Others will use a gentle amount of compressed air. Looks like you are inside, so that might not be your first choice. Take the tripler screws up and clean underneath and look for signs of arcing. Make sure the area around the Anode on the CRT bell is clean. DISCHARGE first, you have HV now, it will hold a charge. There are several spark gaps that may have carbon tracked or on the way, make sure CRT socket is clean and look for discoloration. Sometimes you can see the arc/snap with the room totally dark and listen carefully.

Do you have access to a HV probe to measure the HV?

Hopefully Zeno or others will chime in. I believe the added resister in the Divider Kit was to center the range of the focus control.

Good work ! Comments:.
63-9895 subs to 63-9896 also Only $6 back then !
Use the 4.7meg to center F & check the HV.
Check CRT socket. Look & smell. Most get damaged.
I dont see jail bars :banana:
Arcing. Sit behind it with lights out to spot the flash. Around the anode
they would sizzle from to much HV & leave carbon tracks. Clean up
real good with 91% isopropyl. The 2 hole anode cap also. IIRC
P## is 15-276-01 for the two holer.
Chromatic ON switches to a 2nd set of controls for bright, contrast,
color & tint. They are accessed through the hollow control shafts.
I always ran it in off pos.

On my 1971 Zenith hybrid I think I added 10-20M in series with the ground as it drifted over a couple of years in the early part of using it as a daily driver over a decade ago. Interestingly it stopped drifting and has been stable for years now.
If the focus divider is off the HV and has a path to ground then it will automatically discharge the HV after a few seconds...A splendid feature of that circuit.

Thank you all for your generous help! Certainly would not have gotten to this point without it.

I will make a list of items to work on a knock them off the list when I can. I think cleaning the contacts on the duramodules will also go a long way.

There is definitely some carbon tracks on the socket (I believe visible in one of my early photos of the set) so that will get the cleaning treatment and possibly a replacement if its too bad.

I found the source of the snap. Its my fault. There voltage divider kit I used had too short of cable for the focus and ground wires. I spliced it with the wires from the old divider (solder) then filled around the solder with silicon and heatshrinked it. Apparently it wasn't thick enough and its arcing from the solder joint to ground (about a millimeter arc). Is there a more suitable way to lengthen high voltage cables besides finding the right kit?

IMO Probably not without a suitable insulated inline connector. Zenith in later designs evolved away from the exposed focus tie point on the flyback frame. The "CAUTION HIGH VOLTAGE AREA" label to the left of the tie point is quite appropriate.

It looks like the ECG or NTE HiDIV4 which is also a SK3871/DIV-4 is a nice part to have for this application. Multiple mounting options and long leads for every need.

Not to confuse things but you still have the option of going to a Tripler with an internal divider. I will try to post a scan from Sams 1375 tomorrow that indicates the Late Production 25DC56 and 25DC58Z went to a 212-141 Tripler. Which was "Preferred to CR224 and R361"

If you plan on watching this set, which is a really nice TV, the best advice would be to use the right part in the end, whichever direction you go with the focus divider. What you have now was useful for troubleshooting. Interesting, the Avanti series are still sought after. One of the few sets you could sell and get your money back out of it...... you would not want to quit your day job...

In your previous pictures the greenish tint on the back of the CRT socket is an ominous sign.

Don't forget the Degaussing thermistor from your earlier post. I can't tell from the picture if it is cracked or the lead broke off or not.

These are the changes documented in Sams for the 25DC56 Late Production. I haven't had any luck finding a copy of the Zenith manual. Interesting they added the spark gap as well.

Easy Peasy. Double wall heat shrink and corona dope - Corona Dope is an anti-corona coating with a high voltage/mil strength that is used to prevent arcing. Double wall heat shrink (available from NTE) is what we used - with 100% success.

Corona Dope - GC 10-5002 is the good stuff. Dod specified it for connections above 40KV on airborne radars, followed by Humidseal. We used it with the AWG-9 (Tomcat) radar. Let it dry well before shrinking the heat shrink to prevent cracking (from uncured layers within...)

Double-wall heatshrink - NTE Part No: 47-23248-R (red) - 3;1 shrink ration, 3/16" and 1/4" cover 90% of electronics needs for HV insulation.

Our bench test jig HV connection was jury-rigged - we used a plastic squeeze bottle like they use for ketchup in restaurants. It kept the connection from arcing - and only one hole needed drilling.

Thank you for the info on the substitution! My apologies in the delay, I had to step away from the set for a couple weeks. This TV will be a daily driver once I get it all sorted.

I've got a saved search should a 212-141 show its face, but so far no luck. Unless the focus divider I am using just doesn't work out, it will probably stay as I also have a NOS 212-130 universal tripler ready for use.

I agree on the socket, that will be taken apart and cleaned. Hopefully it doesn't require a replacement. I have also ordered a replacement thermistor per the service manual (surprisingly still available). The old one is cracked in half. Apparently it is common for these to just crumble away over the years.

The parts you listed have just arrived in the mail. I've never seen so many warnings of death and harm on a such a small bottle... :smoke:

I'll be waiting for a warm day to do this outside. Thank you for the recommendations!

Finally had a nice warm day. I was able to correctly extend the divider wires with the red-x corona and double wall shrink tubing. So far no arching!

I opened up the picture tube socket and it was pretty clean. I removed any light dirt/traces and buttoned it back up. The degaussing circuit thermistor was replaced with an equivalent IAW the service manual. I also replaced the divider resistor with the one including in the kit (I forget the ohms off the top of my head). It helped with the focus, but what you see in the pictures is maxed out. For good luck, I cleaned all of the dura-module pins and re-seated each one.

Long story short, we have some real life now! I gave it a quick pass with the deguass wand and that sorted out most of the impurities. However, it is in dire need of a convergence alignment. I'm hoping that this will help with focus as I am still not impressed with it. The picture is currently wider than it out to be (need to find the horizontal adjustment) and there is some vertical linearity issues that the adjustment couldn't quite sort out.

Next up is to de-oxit the control pots and work on going through the service manual for calibration.

Is there anything that I should replace on the dura-modules before continuing? This TV will be a daily driver once fully up and running. Of note, I got a nasty shock when I touched the metal frame around the picture tube on the front of the TV after powering it up for the first time. It did not occur again. Not quite sure what was the cause of that.

On the 9-57 hoz board check for a 330 ohm IIRC. go to a
1 watt film.
Clean the service switch ( rear ) & normal - align sw ( top ).
Semis on modules if they plug in should be cleaned. If they go int
remove the socket. The sockets were more trouble than the parts.
Remember when doing the conv. the center is ONLY the center.
Ignore T, B, & sides. Brite & contrast should be about 1/2 turn
so as not to drive it too hard.

73
Zeno:smoke:

If the set is focusing such that you can defocus by rotating the control either direction from optimum, turn down the brightness some and adjust the focus again as well as the fine tuning...If the pot is at one extreme adding something 2M resistance to the end the end it's butting up against may help.

Hello all,

Sorry for the hiatus again. I've had time to spend a solid day working on this set. Items replaced before starting:

S-84384 coil (my slug broke inside)
212-72 rectifier (mine was cracked and falling apart)

I was able to replace all but the Chroma Duramodule with NOS modules that I happened upon.
I added another 2M ohm to the focus pot such that I can get to either side of out of focus and then center it. Personally I think its still blurry but that is either my expectations are a little high for the set.
I also noticed that the image is shifted to the right. I cannot find any horizontal position adjustments however.

Following the manual and advice I just cannot seem to get this set to align properly. My left and right sides are always out of alignment against the blue no matter what is tried. Convergence strips needed maybe? Below is the best I could get after about 4 hours. Given the age of the set, what level of compromise should I expect?

Is the vertical linearity as bad as it looks in the photo, or is it just the angle of your camera? Bad vertical linearity can affect convergence.

The angle of the photo skews it. Its not perfect, but its not to that degree. I am going to try adjusting the purity tomorrow and see if that helps any moving forward.

The pix is not up to how they looked. I think the CRT is a little weak.
That will make it hard to set up. Cant tell for sure from up here in NH. !

Check a few things.
Boost, 1K resistor on focus pin if CRT, be sure instant on
is working. Also for laffs check the CRT date codes & EIA ## to
see if its OEM. Check diodes on convergence panel.

73 Zeno:smoke:
LFOD !

In the earlier picture with crosshatch and circles, the height is way too big. If this is still true, it will affect convergence. Make sure the height is correct before proceeding.

Too bad I didn't get this far on it while I was still in CT last year!
I am not sure what you mean by "Boost" but I checked the resistors out when I had the socket apart, all good there. Instant on is working.

I attempted to re-do my purity and I think that helped a bit. I re-seated all of the Semis. The 221-46 Semi on the Chroma Duramodule had two legs fall apart. Thankfully I had a NOS one from another Duramodule and that did the trick.

The CRT is OEM and an AG125VB0P22 (if I read the faded label right) with a date code of 4-13 punched out. Early on I complained of faint letterbox burn in. It never came across in the pictures, but it is certainly there. It wouldn't surprise me that this is a high mileage set. The red gun certainly seems weaker/more orange in comparison to blue and green when turning each color down.

Below are my best shots so far. I'm going to order some convergence strips for the left side. But other than that this may be where the set sits for awhile as I am bit burnt on it.

Is it feasible to source an Chromacolor tube for this unit? I have heard of people who hoard them.

I'm 95% I am dealing with a weak CRT. Hopefully I can find someone with a tester near Denver area.

Would replacing the HV tripler help at all? If that HV divider was destroyed its a possibility the tripler took some damage. I am not sure what the symptoms of too low of HV would be though.

Yup thats the original jug. Almost 50 yrs & still quite usable.
Make a list for subs. CC2 sets are real common & probably use
the same one. Just be sure its a 30 Kv tube. Hybrids will
have 25 Kv so no go. I think you have a 25VDQP22
check the Sams.
The set up looks good. Last test is turn off the lights & turn everything down low. If the pix gets sharper its CRT

Zeno

I've been checking possible replacement tubes off and on lately. I have a line on a NOS 25VAQP22, but I am not sure if it is a possible replacement.

I know the following information.

I have a 25VBQP22 in the set (looked like a D in the picture, confirmed with the Sams).
Per a 1976 Zenith interchangeability guide, the 25VAQP22 and 25VBQP22 (also equivalent to a 25VBNP22) are both replaceable by a 25VCNP22.

Per a 1982 Zenith guide, the 25VAQP22 is listed as a direct replacement for the 25VBNP22.

I am fairly confident that the 25VAQP22 will replace the 25VBQP22 based on that chain of equivalences, but I was wondering if anyone has information regarding this?

I am at the same place with my 25DC56 restoration. My set has the original Zenith 25VBQP22 CRT. I believe my set is low hour but it was plugged in it's entire life, prior to me purchasing it on FB last year. My CRT tests good on a Sencore CR70 but does not test well with the life test. The red gun is the weakest of the 3 and no matter how I set it up, it does not want to track well. The focus peaks but isn't very good. It looks much better in low light. I did not try to rejuvenate/restore because it is still watchable. I'm hoping to get my set to a better level.

I have several generations of Zenith, Video Display, and Sylvania CRT guides and came to the same conclusion you did that the 25VAQP22 was a substitute. I was able to find a VDC 25VAQP22 and plan to install it over the holiday weekend and will let you know. Is the tube you are considering NOS or rebuilt?

I haven't been able to understand how a rebuilt VDC 25VAQ compares to the original Zenith CRT? Black Matrix? How did the rebuilders, Zenith, Sylvania, RCA, VDC, compare with each other?

Zeniths solid states with DC, EC FC & maybe CC chassii are
instant on. Be sure its working, when turned on cold it should come
right up in a few seconds.
All flat chassii & early CC2 uprights MUST have new 22-5001 HV
safety caps IF they are white. Orange ones are OK.
Late EC & FC chassii uses the 4 lead cap. Be sure it is orange.
Also be sure you use the right one ! There are at least 3 others for different
Chassii such as 13", EFL CRT's , System 3 etc. Most uprights
used the 800-860 kit BUT be sure !

enuf fer now
73 Zeno:smoke:
LFOD !

I look forward to hearing back from your efforts! I was able to get a NOS tube, but am currently working the shipping logistics part of it.

I currently have the same issues as well, but have done all of the replacements mentioned by Zeno. (Set comes on quickly). Thanks again Zeno and all who chimed in for helping getting my set to at least the "usable" level it is at.

Hello all, been awhile!

I've got a good Sylvania 25VAQP22 from ETF sitting in the garage ready for an install. I will begin chassis and picture tube removal in the near future. I will be taking my time and attempting to restore the cabinet at this time as well.

I've located the disassembly instructions in the service manual and it looks more or less straightforward. Does anyone have any tips/tricks/gotchas when doing this kind of work? And with this 25DC56 chassis, are there any items I should touch while the chassis is out of the console? I plan on installing a new voltage tripler given how destroyed the divider was.

Most sets the CRT comes out as an assy with DGS shield, conv, yoke etc.
Lift out by sides NOT neck. To have grab room put a box a little smaller under the face of CRT. The cabinet will drop away. Move to a table & transfer parts.
Install.
A helper is good, he can lower the cabinet slowly & hold it up to
get the MTG screws started.
Have fun :thmbsp:

Zeno:smoke:

One other thing. Xcelite used to make an extra long 1/4 inch
magnetic nut driver. I would guess its 25" - 30" long. If you can find one its a must for some sets. Also comes in phillips & #10.
I will see if I can find mine & post the model ## for the group.

Zeno:smoke:

Just one.

Take lots & lots of pics of everything before, and during taking it apart. :thmbsp:

Model for driver is Excelite LL-8-M- 1/4
Overall 21" long. Its needed for 19" Zenith hybrids. CRT screws & tuner screws very hard without it.
I have two of them. Cant make up my mind weather to leave each son
one or get buried with one & let them fight over the other !
They are on E-bay sometimes.

Zeno:smoke:
LFOD !

Most certainly!!

Thank you for the tip about the box, sure that will come in handy! I was able to snag a 21" LL-8-M 1/4 on today, its going to save my bacon.

While I was looking around, I figured I should probably get some proper tools. I picked up an B&K HV-40 probe as well.

I am currently looking at NTSC Pattern Generators and I was wondering if you had any recommendations? I am between the B&K 1246 and the Leader LCG-396. I am leaning towards the Leader for the color bar ability, but thought I would ask around before committing.

Look at the Sencore VA48 & VA62 also. We ran them with good
luck. They will do almost everything. Be sure it has BOTH manuals !

Zeno:smoke:

Picked up a VA62 in good working order. Hopefully it survives the post. No manuals, but thankfully all manuals and schematics can be found freely online. :banana:

Hello all,

Here for the yearly check-in! Glad to see that Videokarma is back up and running. Was a bit worried all of this thread was lost to the wind. I backed it up manually just in case.

Anyhow, finally had some downtime to get into this set again. Turns out my replacement tube is actually a Motorola MV 25VAQP22. Hopefully it works well, at least it is not a rebuild to my knowledge.

Looks like the Tripler was replaced with a "SCI 212-139" at some point. I still plan on replacing it with my NOS Zenith universal Tripler. I did notice that it has a "focus" lead, but the current setup has the focus running through the divider instead. Unfortunately it did not come with the usual documentation in the box so I am unsure the best way to handle that.

Currently repairing the base with some epoxy and giving it a repaint while I work on the electronics. Fingers crossed the swap goes well.

While the label says Motorola, the EIA Code 312 is made by Sylvania. Do you see a date code anywhere?

The yoke bracket is secured with double-sided foam tape, probably no longer pliable. I use a plastic spackling knife to gently separate the bracket from the CRT envelope. You will need some double-sided foam tape to resecure. The plastic yoke cases are also no doubt brittle, baking in place for over 40 years, remove gently.

It would be very interesting to know from the engineers who designed these sets, how long they thought they would last???

Your exisiting Tripler looks original to me. If its producing 25KV and its not arcing, its doing what it needs to and could outlast everything else. You could pull the screws, look for signs of arcing, and clean underneath. Your replacement divider looks good.

While you have the chassis out, consider replacing:

The boost filter, if you are using SAMS its C270 10uf 300v, this capacitor takes a beating, and can impact the picture quality.

4.7Meg 2w resister from the focus control to ground. I often find these drift, so will the focus, the original is a carbon comp resister.

Happy New Year!

Unfortunately no date code, not that I can find anyway. Its possible that Sylvania was the OEM for Motorola's CRTs.

The bracket on the replacement tube fell right off, but it looks like the Zenith one is going to be a bit more a job. I have some good double sided foam mounting tape that will do. Fingers crossed everything comes off in one piece.. this is a very high hour set.

As for the tripler, the I replaced the divider after the old one was cracked and covered in HV putty. After seeing that, I am suspicious of the tripler, even if it looks fine. I've got it all apart so might as well while its out and keep the SCI as a spare.

I'll take a look at those components and see if I can source some replacements.

Since I had to epoxy the base and repaint it, I figured why not make the set unique. I give you the Golden Sunshine Avanti.

It's definitely unique. If I was going to go with a custom period color I think I pick Avocado green though.

I looked for a good Avocado green that was gloss and worked for both plastic and wood, but no dice. We had a few favorable days of warm temperature before it goes back to cold so ran with the next best color I could find.

Got around to putting the chassis back in and firing it up!

Got snow and then hooked up the function generator and got worried with the crosshatch image. Triple checked all of my connections were correct and finally found the culprit. Turns out I knocked one of my socketed transistors on the Horizontal module out and it was just laying on the chassis. Thankfully it didn't short any connections. Hooked that back in and got horizontal lock.

Lots of adjustments needed, but it works! Tube appears strong. I ended up removing the extra 4.7 MOhm resistor in series from when I installed the new divider to allow the focus to center.

Work done on the chassis: NOS universal tripler, replaced the 10 uF 300V capacitor as previously recommended, cleaned (deoxit + wire brush) all module connections, DeOxit + Fader Lube on all pots, overall clean to get rid of grime.

On to what will no doubt be a lengthy alignment period. Glad it didn't blow up.

Your new CRT does look strong! A great amount of what you are seeing will clean-up with purity and static convergence. Excellent progress!!