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  #16  
Old 08-29-2011, 11:20 PM
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reeferman reeferman is offline
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Pete,
The neat thing about the Zenith remote was that if we didn't have one handy at the shop we would vigorously jiggle a key ring. If the set responded in any way we knew the remote was working. Phil
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  #17  
Old 08-30-2011, 05:26 AM
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Quote:
Originally Posted by reeferman View Post
Pete,
The neat thing about the Zenith remote was that if we didn't have one handy at the shop we would vigorously jiggle a key ring. If the set responded in any way we knew the remote was working. Phil
Phil, Pete
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  #18  
Old 08-30-2011, 09:32 AM
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Originally Posted by ChrisW6ATV View Post
The remote controls are apparently the "wheeze" ultrasonic type, much more basic than RCAs of the same era (but they never need batteries!).
How do they work?

Phil Nelson
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  #19  
Old 08-30-2011, 10:27 AM
DaveWM DaveWM is offline
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they have a little bellows inside, and a couple whisles pushing down the button compresses the bellows and opens up a whisle. The down side is the bellows can get old and crack, and the seal of the whistle to the mech can leak.

I have one on a B&W maggie, works well. the remote unit had a shorted transistor, but it was easy to fix, a few low volt caps. The volume is just a voltage divider on a rotoray switch, the on/off on mine was tied to the tuner, it would go off when in the un used UHF. On some combos its a real challange just to understand how to turn them on and off.
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  #20  
Old 08-30-2011, 12:50 PM
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ChrisW6ATV ChrisW6ATV is offline
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Originally Posted by Phil Nelson View Post
How do they work?

Phil Nelson
Phil-

As Dave described, you push the button down and a puff of air comes out the front, I assume with a high-pitch sound component that activates one of two tuned circuits in the TV with relays to the tuner and power switch (and volume, somehow?). What is strange is that both buttons go down most of the way when you push either one, but I guess the correct one goes enough further to activate its air puff and not the other one.
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  #21  
Old 08-30-2011, 03:09 PM
DaveWM DaveWM is offline
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the channel is just a relay that pulses the motor on the tuner (one direction only), the volume is a solenoid activated by a relay, it pulls a ratchet that spins the rotory switch on which is the beforementioned voltaged divider network of resistors, IIRC 4 (mute low med high). All this is mounted on the receiver unit, the audio from the TV plugs into the receiver. there is a switch that turns on the power to the unit (has its own PS on the receiver) and routes the audio to the rotoray switch. If the remote switch is in the off posistion the audio bypasses the receiver and goes directly to the amp.

the main volume control still works, like a master volume if the remote is active, even with only 4 levels it allows tayloring the output to personalize the low/med/high. When the remote is off its just like any other volume control.
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  #22  
Old 08-30-2011, 07:22 PM
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Dave-

Thank you for that clear description of how this type of remote control system works. On my set, there is a spot on the back panel where the remote control on/off switch is labeled, but the switch itself is not there (nor is there a mounting hole). This set does have two other switches on the back: A "fast warm up" on/off switch (that was off when I got the set, probably helped the CRT live longer), and a "sepia tone" on/off switch (that would change the color temperature, I am guessing?).
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  #23  
Old 08-30-2011, 08:35 PM
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thats the same chassis as my combo, yes it should have a top on the fly cage, but I doubt its any thing to work about.

the chorma board will need some new caps .01 on the grid of the 6GU7, I guarntee the one that sits between the tube and the power resistor is weak, the other two are prob ok. Will it work if weak, yes, did I change mine, yes. did I need to, yes but thats more a personality defect than a color TV defect

there is prob a couple .001 1kv caps that should be replaced, the one on the vert out transformer was bad on mine, the one the audio out transformer was not, replaced them both. I also like to replace the .1 on the grid of the video tube and the .001 that couples the horz osc to the horz out, just for good insurance againt leakage. This is the general same thing I did on my other RCT sets of that era.

Check those wires on the top of the chorma board (think there are two behind the 6GU7's goes to a couple power resistors jumpers on the board).

I have had several that were corroded and break, make is look like the screen drives were turn up on one color when this happens). I just use some tweezers and gently tug on them, if they are corroded they will snap right off, if they dont, then you are prob ok, as they dont get moved at all.

besides those coulpe 1kv tube caps I think the only other paper caps were the across the line cap at the power receptical and the black beauty that is used on the horz osc coil (mounted vertical). I replaced the accross the line with an X2 and left the horz osc coil alone after it tested perfect (I did not have a precison cap for that value handy).

all the normal gound stakes should be looked over and take a close look a the bottom of the video amp tube, it gets hot and the solder can look crystalized. I reflowed some questionalble looking joints.
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  #24  
Old 08-31-2011, 12:18 AM
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Dave, I appreciate all the details of needed parts and things to check. I am looking forward to getting this set working, so I'd better get moving with my other projects too!
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  #25  
Old 09-02-2011, 07:34 AM
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Chris, Find a book titled "Magnavox Volume 1 - Color TV Service Manual" by Stan Prentiss, published in 1974 by TAB Books (out of print). This had factory schematics, functional circuit descriptions, service and alignment procedures plus case histories for trouble shooting. These books were very helpful and were published for most of the manufacturers.

see this long link: http://www.amazon.com/gp/offer-listi...=olp_tab_used?ie=UTF8&coliid=&me=&qid=&sr=&seller=&colid=&condit ion=used

Good luck, that is a unique cabinet style from one of the best in TV-furniture. Magnavox of this vintage is usually an easy fix. drh4683 has a very good video on Utube to remove the cataracts from that CRT.
Dave 63

Last edited by DavGoodlin; 09-02-2011 at 07:36 AM. Reason: link trouble
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  #26  
Old 09-02-2011, 11:42 AM
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Quote:
Originally Posted by ChrisW6ATV View Post
Dave-

Thank you for that clear description of how this type of remote control system works. On my set, there is a spot on the back panel where the remote control on/off switch is labeled, but the switch itself is not there (nor is there a mounting hole). This set does have two other switches on the back: A "fast warm up" on/off switch (that was off when I got the set, probably helped the CRT live longer), and a "sepia tone" on/off switch (that would change the color temperature, I am guessing?).
You are correct regarding the sepia tone switch. This switch was labeled "sepia switch" on some makes of TVs and serves to inject a soft blue color into a black and white picture. Some Silvertone color sets of the '60s had a front panel control labeled "Chromix" that did the same thing; however, the adjustment was so critical and sometimes confusing that most people just set it at midrange (neutral) and forgot about it. The sepia switch was often (probably more often than not) left in the off position because many people didn't know its true function, although the switch and its function probably was mentioned in the instruction manual. Many viewers didn't care about adjustments like this, as long as the picture looked halfway decent. There are people who will watch horribly misadjusted color TVs (I have known a few), not caring what the picture looks like as long as it is there. Today's color sets are built such that little or no adjustments to color or contrast, brightness, etc. are necessary; viewers need only turn on the set, select the channel they want to watch, and forget the rest. This was why automatic fine tuning (AFT) controls were designed into color TVs beginning in, I believe, the '70s -- because many viewers could not fine tune a color picture properly (most viewers did not realize that if the fine tuning is not set exactly on a color set, there will be no color), and automatic color adjustments quickly followed.

Magnavox's "TAC" (Total Automatic Color), Zenith's "Color Sentry", et al. were other automatic systems designed into TVs of these makes for the same reasons, although many times the picture looks terrible with these automatic controls activated; many times it is possible to get a much better picture by adjusting the manual color and tint controls until the flesh tones are correct, although again many viewers did not want to be bothered with those controls. The reason the picture is often better with the automatic controls disabled is that these systems, which were often little more than push button switches that activated preset controls, were probably adjusted at the factory using color bars from a generator rather than actual air signals.
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Last edited by Jeffhs; 09-02-2011 at 11:48 AM.
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  #27  
Old 09-02-2011, 08:25 PM
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Thumbs up

What a beauty...and a RE phosphor tube to boot!
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  #28  
Old 09-04-2011, 01:25 AM
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ChrisW6ATV ChrisW6ATV is offline
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Chris, Find a book titled "Magnavox Volume 1 - Color TV Service Manual" by Stan Prentiss
OK, I see there are a couple on Amazon now too. Thanks for the tips.
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  #29  
Old 09-04-2011, 01:33 AM
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ChrisW6ATV ChrisW6ATV is offline
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Magnavox's "TAC" (Total Automatic Color), Zenith's "Color Sentry", et al. were other automatic systems designed into TVs of these makes for the same reasons, although many times the picture looks terrible with these automatic controls activated.
Jeff-

Thanks for the notes. I have a book that may be "Color TV Servicing Simplified-Volume 3" (by Milton Kiver?), and it describes Magnavox as having one of the first color-"correction" circuits intended to push colors toward skin tones; this book is from the rectangular-CRT era, and I also remember reading about those one-button color systems in the early 1970s (way before I ever had a color TV) and how they made things usually worse rather than better.
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  #30  
Old 09-12-2011, 09:38 PM
julianburke julianburke is offline
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RE in the prefix was for RARE EARTH.
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