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 Post subject: RCA Strato World Mark One Disassembly
PostPosted: Dec Tue 05, 2017 4:51 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 3619
Location: Near Brandon, Iowa
I recently purchased a Strato World Mark One (ca. 1969) in mechanically-damaged but generally working condition. This model of radio is completely alien to me- I'm a longtime collector of Zenith TO tube and transistor portables and have a couple of RCA Strato World (tube type) sets in my collection, but have never heard of this particular model. It appears to have been aimed at the same market as the Zenith TO 7000. It is a Japanese-made multiband radio with some decent features like bandspread, tuning meter, and BFO, but the map light is nonfunctional (the light bulbs themselves test OK) so I need to pull the chassis out of its case to examine the lamp switch.

Haven't been able to locate any service info on this set, but that's not of immediate concern to me since the radio functions themselves seem to be in good shape on all bands. The sticking point is: how do I extract the chassis from the plastic case? It appears that it is retained by three long hex posts and one phillips-head screw; but I am concerned that there may be some subtlety that I am missing. Does anyone have any experience at tearing one of these radios apart?


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 Post subject: Re: RCA Strato World Mark One Disassembly
PostPosted: Dec Wed 06, 2017 12:40 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5814
Location: Black Hills, SD 57745
Any access to the switch to probe for continuity, voltage on the contacts or the ability to short the switch to see if that lights the bulb? The wire(s) may be pinched so check the lamp socket (unpowered) both sides to ground for continuity. Only one side should be grounded, of course. In the case there's voltage at the socket, make sure the center lug makes contact to the lamp's solder button.

In my TO-3000, the lamp has it's own single D-cell in the battery pack for power, so there's another angle to look at to make sure all the holder contacts and cells are good. I don't know how it's wired up in the Strato World.

It'd be great not to have to disassemble just to get the dial lamp going!
-Ed


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 Post subject: Re: RCA Strato World Mark One Disassembly
PostPosted: Dec Wed 06, 2017 2:46 am 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 3619
Location: Near Brandon, Iowa
Ed in SoDak wrote:
Any access to the switch to probe for continuity, voltage on the contacts or the ability to short the switch to see if that lights the bulb? The wire(s) may be pinched so check the lamp socket (unpowered) both sides to ground for continuity. Only one side should be grounded, of course. In the case there's voltage at the socket, make sure the center lug makes contact to the lamp's solder button.

In my TO-3000, the lamp has it's own single D-cell in the battery pack for power, so there's another angle to look at to make sure all the holder contacts and cells are good. I don't know how it's wired up in the Strato World.

It'd be great not to have to disassemble just to get the dial lamp going!
-Ed


The SW dial is lit by six grain of wheat bulbs. There are two bulbs for "low level" lighting and four more to illuminate the clear plastic relief world map superimposed on the dial scale; two momentary pushbuttons select between "dial" and "SW map" lighting. There is at least one additional bulb that illuminates the separate Broadcast AM-FM circular dial scale. My guess is that there are actually two bulbs on this latter scale, with one burned out (only the right side of the dial is lit up, which is probably not what the manufacturer intended).

Presumably the flip-up shortwave dial scale and the circular AM/FM dial lamps are actuated by the same "dial light" pushbutton. So, my guess at this point is that the ground wire in the three-wire bundle that goes through the hollow lid pivot to the two sets of SW dial maps has opened up- that would explain why neither set of lights work (even though all bulbs are good). Unfortunately, to repair this wire bundle the chassis has to come out of the case.

This is a pretty cool radio... unlike the transistorized Zenith TO series, this set uses three separate ferrite-rod loop antennas for longwave, standard broadcast, and shortwave AM. There is a telescoping rod antenna but it is only used for FM.


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 Post subject: Re: RCA Strato World Mark One Disassembly
PostPosted: Dec Wed 06, 2017 6:28 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 19403
Location: Utica, NY 13502 (USA)
Perhaps this old thread will be of some interest:

viewtopic.php?f=4&t=94688

I posted this 9 years ago and I'm sorry that I don't remember how I got the chassis out of its case. I do remember that it was somewhat of a challenge, however. I sold the radio to a friend who still has it and says it still works fine.

Dave


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 Post subject: Re: RCA Strato World Mark One Disassembly
PostPosted: Dec Thu 07, 2017 12:47 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5814
Location: Black Hills, SD 57745
There's sure a lot more lamps in there than I guessed!

Generally, when I yank an unknown chassis, I loosen the most likely fasteners and lift it a bit to see what comes up or stays put. Some might be a subassembly attached to the main chassis, and those screws should remain. After some gentle or less gentle (as frustration dictates) and watching for wires... but I think we've all been down that road! I hate taking the chassis out of my ZTO 3000, and I need to to fix the earphone jack. Ugh!

-Ed


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 Post subject: Re: RCA Strato World Mark One Disassembly
PostPosted: Dec Thu 07, 2017 9:07 am 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 3619
Location: Near Brandon, Iowa
Thanks to all who responded. I managed to get the chassis out of its case with really no trouble... after I figured out "the trick".

The chassis is held to the plastic case by three hex posts and several small phillips-head screws. The factory thoughtfully marked these with a dab of red lacquer so that it was fairly obvious which ones needed to come out. However, removing all of these threaded fasteners in the back of the set still saw the chassis being held fast.

"The trick", as it turned out, was a small phillips screw in a front panel recess next to the tuning knob shaft. The large tuning knob skirt normally covers this screw, so it isn't very obvious. Removing this screw freed the chassis and allowed it to be pulled out of the case, after having depressed all of the band-select pushbuttons enough to clear the plastic backing bar behind them. There was enough of a service loop on the speaker and tuning meter wires to make unsoldering them not necessary, at least for my immediate objectives.

For the record, I did discover that the circular standard broadcast AM/FM dial was supposed to be lit by two grain-of-wheat lamps- but the left one was in fact burned out. I'm thinking about biting the bullet and replacing all eight lamps in the set, just because I dread ever having to open up this set again.

Restoration of this set (re-capping, alignment) seems to be out of the question without documentation.


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