View Full Version : 1967 Magnaovox Stereo Theatre


amglow
02-21-2017, 08:17 PM
I found this 1967 Magnavox color Stereo Theatre on the local craigslist last week and couldn't pass up the opportunity to grab a radio phonograph tv combo. First of all, I must say that I have never worked on a television before. I have worked on radio equipment, however. So I am a TV novice. The limited research I have done seems to indicate the mid 1960's Magnavox TV's were somewhat of a problem child. The early 70's straightened out many of the issues. Is this true? What do I need to look for on this TV, besides the normal capacitor replacement and resistors out of tolerance? It has an RCA "Hi-Lite" NW-H7881 picture tube. Any pointers are greatly appreciated. I want to keep this set original and not replace the TV with a flat screen or bar!

Jon A.
02-21-2017, 08:58 PM
I found this 1967 Magnavox color Stereo Theatre on the local craigslist last week and couldn't pass up the opportunity to grab a radio phonograph tv combo. First of all, I must say that I have never worked on a television before. I have worked on radio equipment, however. So I am a TV novice. The limited research I have done seems to indicate the mid 1960's Magnavox TV's were somewhat of a problem child. The early 70's straightened out many of the issues. Is this true? What do I need to look for on this TV, besides the normal capacitor replacement and resistors out of tolerance? It has an RCA "Hi-Lite" NW-H7881 picture tube. Any pointers are greatly appreciated. I want to keep this set original and not replace the TV with a flat screen or bar!
Good for you. :) The "upcycling" trend has been done to death.

I'm not familiar with this kind of Maggy, being a novice myself who's done a lot more reading than repairs. There are plenty of sets far more problematic than yours yet many of them are among the most popular sets here.

That picture tube number isn't the tube type, that number would start with 25 or 23V and end in P22.

Electronic M
02-21-2017, 09:46 PM
A color TV is like doing 3-7 radios at once with each set interlinked and feeding off each other's work.
Recap and tube checking alone will get many radios and some TVs going. But just as there are dog radios that need tough trouble shooting after the recap to work most TVs have need for troubleshooting as well as adjustments.

Don't mess with RF/IF alignment in TVs...That requires specialized equipment, and even with such equip is very difficult.

Tube based color TVs when used as much as they would have been when new, are not "fix and forget", but rather fix, and in .5-1.5 year fix again, rinse and repeat....These era sets are complicated and drive some parts HARD things wear out from use.

DavGoodlin
02-23-2017, 03:41 PM
I have had my hands in a few Magnavox Color TVs of that Vintage. The chassis tag will identify the series such as T933, U924, etc. Much of this TV's circuits resemble RCA with a few wacky things that only Magnavox did based on their audio systems design. i.e. 6BA6 AFC tube, 12AX7 pincushion amp

Almost all the Magnavox TVS made through early 70s, before their better solid state chassis TV sets, can be a "problem child" in some areas such as the luminance-video and CRT drive circuits, but not anything you can't get answered here. Its just solder joints, dirty pots and out of tolerance parts just like it is on Mag tubed HiFi consoles.

That is a worthwhile project mainly because you have an all-new RCA Hi-lite CRT and you also have a higher-end solid state Astrosonic receiver with the typical well-matched speakers.

Simple advice: Work on and finish the stereo receiver first, then that good record changer and finally, put on some records --- fixing that TV will go easier and you will not be tempted to give up.

TV Engineer
03-14-2017, 06:41 PM
I worked for Magnavox service in the 1980s, and worked on many of these sets. There were tons in daily use in my area. They are no more or less problematic than any RCA or Zenith of the era. I will say though, they produce a superior color picture when serviced correctly. The stereos sounded amazing, and the record changers were the finest made. I never played my records on anything but a Micromatic, and they're as good as new. I see your set has remote too, and those are easily made operational by just replacing all of the elctrolytic caps in the remote chassis. It also looks like yours is the 704040 remote chassis, which included an auto off feature. It would shut the unit down after the TV station it was tuned to left the air for the night.

If I can be of any assistance, please contact me.

zeno
03-15-2017, 10:06 AM
When you get to the TV fix things one problem at a time.
Dont jump in & order a bunch of tubes & caps first.
Start with getting the screen lit ( a raster ) & work from
there. Next step is making it a good B&W. Then you do
any color problems & detailing.........

Maggys were a good set but I personally didnt care for them.
They always had the best cabinets & HiFi's.

73 Zeno:smoke:
LFOD !

DaveWM
03-15-2017, 10:19 AM
nothing special good or bad, as mentioned tube based TV's are no where near as reliable as solid state stuff, but then again not a lot of parts and not hard to diagnose if you have a scope. The problem is the TV signal packs a lot of info on it, and demodulating it is very different with 3 things going on (AM/FM/PHASE) add to that then need for exacting sync esp on the color means more challenge but then again more fun when you get it right.

I see a brightner in there, hopefully the crt is not toast but if it is they are not hard to come by.

I would suggest a slow start up with the horz out and the vert out tubes removed from the circuit. Monitor the B+ and variac it up slowly (this assume its been out of service for some time). If the B+ comes up (should get to about 400v). then go ahead and plug those output tube in it, put a ma meter in series with the cathode lead of the horz out (you don't want more than about 220ma max) and to a full power start up.

This establishes a base line operating condition for the set, from there you can determine if any of the systems work and contcentrate on those that do not.

things to avoid, mass clean up, maggies will have a lot of slimy goo on the all the wires that interconnect the stereo/tv/speakers. there will be a lot of dust all over the chassis. Do not clean this up until after the baseline. If it works do not clean it anyway, a dirty chassis pcb that works is better than a clean one that does not.

If the dirt really bothers you, clean as you go so if a new problem pops up, you can go back to where you just cleaned. this is the same as only doing a cap or two at a time vs a shotgun recap.

the most likely issues will be vert defection and maybe power supply caps.
Often that era can caps are fine so hold off on replacing until you know they are a problem. There are lots of resistors/small caps/wires all tucked in tightly to the can lugs, so what I do is if the cap is bad, just saw it off from the top, drill holes thru the base of the can, install caps (radial thin work best) from the top and you leave the lead dress below untouched.

the vert deflection caps have a hard life, look for 1000-2000v rate film types in the feed back circuit. they get leaky and foul up the process.

jstout66
03-15-2017, 12:25 PM
What Zeno and DaveWM said.
Of sets of this vintage, you're not going to have a lot of cap issues.
Basically, it's troubleshoot and repair if it doesn't work as is.
I saw the brightener on the tube as well, so hopefully it will still be good.
Tube was replaced in 71. Not sure why certain shops got on a brightener kick. We weren't a big fan, but if the customer had NO money for a tube replacement, we did that as a last ditch effort to keep it limping along (and that was if a rejuvenation wouldn't work)

Jeffhs
03-15-2017, 05:48 PM
I worked for Magnavox service in the 1980s, and worked on many of these sets. There were tons in daily use in my area. They are no more or less problematic than any RCA or Zenith of the era. I will say though, they produce a superior color picture when serviced correctly. The stereos sounded amazing, and the record changers were the finest made. I never played my records on anything but a Micromatic, and they're as good as new. I see your set has remote too, and those are easily made operational by just replacing all of the elctrolytic caps in the remote chassis. It also looks like yours is the 704040 remote chassis, which included an auto off feature. It would shut the unit down after the TV station it was tuned to left the air for the night.

If I can be of any assistance, please contact me.

I don't think the auto-off feature was necessarily unique to Magnavox. Some years ago, I had a 19" Emerson table model TV that also had the same automatic shutoff function; it would, like the Magnavox being discussed here, turn off the TV after the station the owner was watching signed off. Of course, today these auto-shutoff systems won't work, since all TV stations run 24 hours a day; they do not sign off except in case of an emergency (one of the stations in Cleveland left the air for about six hours a few months ago after lightning struck one of their antenna towers, but that was the only time in the last ten years or so I can recall that station ever being off the air any extended period of time).

My set also had a peculiar habit of shutting itself off almost every time there was a lightning storm in the area. The storm didn't have to cause a power outage; the set would shut off any time lightning struck anywhere near my house. The TV antenna was in my attic, so I was never concerned about a lightning strike on it, but the TV shutting off after nearby lightning strikes always puzzled me. Perhaps the auto-shutoff feature may have had something to do with it? :scratch2:

amglow
04-07-2017, 05:45 PM
I want to thank everyone for the incredible knowledge shared here for this television restoration. I do, indeed, intend to keep it as original as possible. I will concentrate, for now, on what I know best; the stereo restoration. Once I have the stereo playing well, I'll probably attempt the restoration of the television. Lastly, the record changer. I definitely want to see the color television come alive. Neighbors across the street from us, when I was a pre-teen (1960's) had a Magnavox Stereo Theatre. I look forward to seeing some vintage movies roll across this screen.

I guess the "7126" stamp on the RCA Hi-Lite tag indicates a tube built in the 26th week of 1971? I believe this model Stereo Theatre was from the 1967 time frame. Would a CRT go bad that quickly? Where would the actual CRT model number be located? I know some are located on the bakelite tube neck, where the pins are located. However, this CRT has no bakelite pin mount. It's very low profile. Just a thin wafer.

knowing I have a CRT to check, I purchased a CRT tester. It's a Hickok model 265. I purchased it because I have a couple of their military and commercial pieces that have proven very good quality. It also has all 11 CRT attachments. Have any of you had any experience with this tester? Good/bad? It looks like a newer style tester from the 1970's possibly. I'll attach an image for your review.

DaveWM
04-07-2017, 10:58 PM
rectangle tubes are not that rare so even if it test bad no sweat.

Electronic M
04-08-2017, 01:14 PM
Usually there is a label on the bell of the CRT usually on the side usually near the screen that will have the ID number on it...It may be hidden under the shield. Is there a tube layout for the TV section inside the set? If so it should list the CRT (probably a 25XP22 or something similar)....Honestly the guns in large screen delta-gun tubes (anything bigger than 20") are pretty much all the same and should use the same test settings.

DavGoodlin
04-09-2017, 08:43 AM
I have never seen a Hickok CRT tester but if its anything like the tube testers Hickok built, its among the best. Make sure you let the tester on it for at least a few hours and see how emission readings climb. Sometime this is all you need to do without using clean-restore-rejuvenate functions.

I can speculate that original CRT may have lasted 5 years and that was not unusual based on some anecdotes shared here. A Zenith or RCA CRT of that era usually lasted over 10 years. That date code is possibly a few weeks before the earliest date of replacement but it could have been a few years later, too. A hi-Lite tube is all-new, not rebuilt like the Colorama series.

Marco-nix
04-10-2017, 09:16 AM
I found this 1967 Magnavox color Stereo Theatre on the local craigslist last week and couldn't pass up the opportunity to grab a radio phonograph tv combo. First of all, I must say that I have never worked on a television before. I have worked on radio equipment, however. So I am a TV novice. The limited research I have done seems to indicate the mid 1960's Magnavox TV's were somewhat of a problem child. The early 70's straightened out many of the issues. Is this true? What do I need to look for on this TV, besides the normal capacitor replacement and resistors out of tolerance? It has an RCA "Hi-Lite" NW-H7881 picture tube. Any pointers are greatly appreciated. I want to keep this set original and not replace the TV with a flat screen or bar!

That is what i want and they rare where i live in Canada :( you've a nice model

Zenith26kc20
04-10-2017, 11:13 AM
Looks like a T-933 chassis (my avatar)! Boost diode, horizontal blanker tube (makes a crt look bad), check all tubes! Be sure to dip horiz output current! Mine was 220 milliamperes when I got it, now it's 194 milliamperes. Be careful, the tuner is fragile! I remember they did eat a flyback but no more than RCA sets did. Mine has the original and still runs cool. Has that strange "chroma-tone switch that turns the background sepia. Be sure the setup switch is clean. These can make a good picture!
And the stereo can break a lease, if necessary.......