Well, I did it again. Hauled home yet another old console television that I found on the side of the road. It's a Magnavox, and I dragged it home - I still don't really know why. The cabinet is in pretty bad shape, the finish is totally shot, and the veneer is flaking at the edges. But, it was a black and white console... I just took the back off it a few minutes ago - I couldn't believe it - this thing is solid state! It uses a 24HAP4 picture tube, but it's solid state! It fooled me with the cabinet interlock on the back, and the general appearance of the set. I could've sworn that it was a tube set. I didn't even know they _made_ solid state black and white consoles. It's an interesting set, but I haven't figured out what I'm going to do with it as of yet. I think I'm going to see if I can make it work. It comes on, and I hear deflection and the sound works. But I don't get a picture or a raster or any light on the screen, and I can _barely_ see the picture tube filament. It's still got a silver getter though, so it hasn't gone to air. Hopefully the tube isn't worn out. I'll have to check the power supply when I get a chance. All I know at the moment is that the electrolytics aren't shorted - could still be something wrong with the caps though. The set has a power transformer, as well as what I believe to be a smaller power transformer for the filament supply. I'll do some more investigating when I have time. If I have time... I'll also have to post some pictures tonight.

-Ian

Motorola also made some large screen B/w solid state sets, these and the Magnavox are very robust and high quality. Usually these old sets still use an hv tube rectifier so this may be a point to check, there may be no hv to the crt.

Astro-Sonic is the name Magnavox used for their solid state equipment. Those early solid state TV's were kind of troublesome, there was a recall on the flybacks in the early ones because they had a black wax covering on them and if they arced over they tended to catch fire.....

Well, I did it again. Hauled home yet another old console television that I found on the side of the road. It's a Magnavox, and I dragged it home - I still don't really know why. The cabinet is in pretty bad shape, the finish is totally shot, and the veneer is flaking at the edges. But, it was a black and white console... I just took the back off it a few minutes ago - I couldn't believe it - this thing is solid state! It uses a 24HAP4 picture tube, but it's solid state! It fooled me with the cabinet interlock on the back, and the general appearance of the set. I could've sworn that it was a tube set. I didn't even know they _made_ solid state black and white consoles. It's an interesting set, but I haven't figured out what I'm going to do with it as of yet. I think I'm going to see if I can make it work. It comes on, and I hear deflection and the sound works. But I don't get a picture or a raster or any light on the screen, and I can _barely_ see the picture tube filament. It's still got a silver getter though, so it hasn't gone to air. Hopefully the tube isn't worn out. I'll have to check the power supply when I get a chance. All I know at the moment is that the electrolytics aren't shorted - could still be something wrong with the caps though. The set has a power transformer, as well as what I believe to be a smaller power transformer for the filament supply. I'll do some more investigating when I have time. If I have time... I'll also have to post some pictures tonight.

-Ian

"Astro-Sonic" would be the correct term to use for this TV if it also had the solid state AM/FM stereo tuner/amplifier and phonograph. As was stated in another post, the term was also used for Magnavox's solid-state stereo consoles without the TV. I doubt very much, however, if Magnavox (the original Magnavox Company of Fort Wayne, Indiana) ever made a stand-alone black-and-white solid-state console (if they did, I was never aware of it). Most likely your set is one of the early Magnavox solid-state three-way consoles of '50s-early '60s vintage. The CRT may not have gone to air (yet), but the cathode emission may be so low as to render the tube useless. If the set is thirty or more years old, and I would guess yours is at least that old (b&w sets were still being sold in large numbers 30+ years ago, since color was still very expensive through the '60s, '70s and even part of the '80s), the CRT is probably very weak, especially if the set's former owners watched it many hours a day.

No raster would lead me to believe you have either a defective CRT or horizontal deflection circuit problems, although if you can hear the oscillator working (many people cannot because of the very high frequency--15,750 Hz--at which it operates), it's probably OK, though if it is far off frequency (too high) the raster will disappear. (Keep in mind as well that modern sets will shut down entirely if any kind of problems develop with either sweep circuit, and if the horizontal oscillator frequency is too low in a tube-type transformer-powered set, the transformer can be damaged or destroyed.) My experience is limited to tube-type TVs, as I worked on many old junkers, mostly trash-day finds as your set was, at my former home some thirty-odd years ago; I don't have much, or to be honest any practical experience with solid-state sets, either b&w or color. There are many people here at AK much better versed in solid-state color/b&w TV servicing than I am or ever was.

BTW, if you can see only a faint glow in the CRT neck where the filament should be, the filaments may not be getting enough voltage (most used 6.3 volts), or else the filament connections at the CRT socket (base or the socket that plugs onto the base of the tube) are corroded or the base is loose. If you see a blue glow in the neck of the tube, surrounding the elements, the tube is gassy and therefore defective. Don't use a brightener on the tube until or unless you have exhausted all other possibilities for weak or no raster. Using a brightener on a tube with reasonable cathode emission can shorten the life of the CRT, and can cause the filaments to burn out if they are the least bit weak; however, if you use a brightener on a very old, weak tube and the filaments burn open shortly after installing it, it is likely they would have burned out shortly anyway. There have been cases reported, moreover, in which the simple act of walking across the floor near an old TV with a weak tube has caused enough vibration to shake the CRT filament to pieces; this also accounts for many instances (with tube-type sets) in which a set worked one day, then later on that same day or the next, nothing. Tube filaments, not necessarily just those in the CRT, are very fragile and are weakened by heat; it doesn't take much to fracture one that has been glowing red-hot for months or years. The old 117Z3 audio amplifier tubes, used in very early phonographs, were notorious for early failures because they ran so hot and at such high voltages (most such tubes were wired in series with the phono motor, which in turn was connected across the AC line; a common problem with these sets was that the phono motor would not run, the reason being that the amplifier tube filament was open). The 117Z3 filament was, IIRC (it's been years since I've seen one of those line-operated tubes, and I've been working with electronics as a hobby since 1964), made of extremely thin wire and did not last long, especially if the phonograph was heavily used (by teenagers, for example).

Good luck. It's a real kick to get these very old TVs working again after they have been given up for dead by their former owners. Once you get your Magnavox console working again and the cabinet looking good (needless to say, you have your work cut out for you just on the latter if the finish is faded and the veneer is chipping off), I'm sure you will have a TV you can be proud of and will enjoy for years to come. If you decide to sell it on ebay after fixing it up, you can probably get a few dollars for it, as there are a lot of antique TV and radio collectors out there, many of whom are AK members (including myself--I have a small collection of small radios here, several of them Zeniths; I just recently scored a Zenith Royal 1000-1 TransOceanic transistor portable on ebay). Can't collect old TVs anymore because I moved to a one-bedroom apartment from a three-bedroom house over five years ago, but I still like working with old radios. I am also an amateur (ham) radio operator (my callsign appears after my name in my signature), and have been since 1972--33 years.

Again, good luck with that Magnavox TV. It should also be possible to use it on cable if you hook it up to a set-top box (or a VCR if you have standard cable or just an antenna). Put the set's own tuner on channel 3 or 4, hook up the box between the cable and your TV, and you're in business. One of the advantages to using a cable box with an older TV is that most of these boxes, especially the newer digital converters, have remotes, which means you can have a remote control TV (these boxes are set up for, at the very least, remote channel selection, remote on/off and remote volume control) even if the set didn't have remote control originally. Another advantage is that you will save the set's own tuner from further wear; once set on the box's output channel, the TV tuner stays there, with all further channel tuning, etc. being done through the box.

Following from the Magnavox Service manual for the T908 Series Transistor Television Chassis...."The T908 Series Chassis is used in Magnavox Astro-Sonic Television models featuring solid-state circuitry. The chassis employes a total of 22 transistors (18 on the main chassis, 3 in the VHF Tuner, and 1 in the UHF Tuner) plus 23 diodes and one dual-diode for Horizontal AFC. The chassis is designed to be used with 110 degree picture tubes such as the 23MP4, 24AHP4, and 27ZP4. The high voltage section provides 18 KV for the CRT Anode. This is in Magnavox Service Manual Volume 6 dated 1967. The product information section of the manual shows the T908 chassis being used in TV only consoles, 19 inch portables, and combination sets, in the service lit. they are all referred to as Astro-Sonic. I've got one of the 19 inch portables and it says Astro-Sonic on the front. I've got all the service info Magnavox published on these sets if you need a copy. I used to service these sets and remember them as being prone to problems especially in the HV sections. They did use a 1K3 tube for HV rectifier, and by now you probably need a bunch of low voltage electrolytic capacitors. Before you sink a lot of $$$ trying to make it work get the CRT checked, a lot of those 24 and 27 inch B&W tubes didn't last a long time. Good Luck...


Checking further in the manual the version of the T908 chassis that was used in the 19 inch sets was the T915, It's almost identical to the T908 except for the deflection circuit changes to accomodate the smaller CRT....

There is an older thread here, maybe a few pages back, regarding an almost identical set. I thought for a second the old thread was back on top. Anyway, if you can dig it out there might be some more info there.