Magnavox console TV/Hi-Fi

[RetroHacker]

I finally got a roundie! I had to drive all the way to Maryland to get it, but it was worth it. This console is in immaculate condition physically. This is an interesting combination - a solid state stereo tuner/amplifier, and a tube TV. Unfortunately, the TV doesn't work. The radio works, and the phono barely works. It takes a while to get up to the proper speed, and there is a lot of noise in the right channel of the phono preamp. The stereo's sound is actually not that great, it's weak and frail, with no puch or kick whatsoever, and not a lot of volume. Even with the volume and bass controls turned all the way up, it doesn't get too loud, and the bass is still weak. The previous owner replaced the output transistors in the power amp, as well as many tubes in the TV, hoping to get the TV to work. I don't know what problem the amplifier had to warrent new transistors, maybe he was trying to solve the weak sound issue too.

But, as far as the TV is concerned, it doesn't get high voltage. The flyback _looks_ immaculate - no melting, burning, or even caked on carbony crud! The chassis is very clean. I knew about the lack of HV when I got it, and the first thing I noticed was that the lead connecting the HO to the flyback cage was off (you have to remove this lead to remove/replace the flyback box). I knew that this couldn't have been the problem - he'd probably just not connected it back when he put it back together last, but I hooked it up and tried it real quick anyway. I wanted to see how well the TV tuner worked anyway. So, I hooked it up, turned it on, switched the selector over to TV, and watched as the tubes lit up. Then, there was a sharp CRACK and I saw a spark in the right side of the chassis somewhere, possibly a popping capacitor, possibly an arc, I didn't know. I shut it off. I hadn't done a soft start, since this set was powered on recently (not working, but still). I was unable to find any cause for the spark, no burnt marks, nothing. So... I don't know. I haven't done much else, I need to pull the chassis and see what else might be obvious. The set uses the orange dip type caps, but I saw a couple of those "Elemenco" ceramic caps in there, and what looked like a small cardboard electrolytic.

I'd really love to find a schematic for this set, but haven't found any identifying marks on the chassis. The chassis has the numbers 4181 stamped on it, but a search on Sam's website wasn't conclusive.

So, what does everyone think?

-Ian

[Chad Hauris]

There may be shorted diodes or electrolytics in the power supply for the TV. I would connect a series lamp around 100 watts in the power line and see if it glows bright and stays bright. If so, start checking for the short in the B+ or rectifier circuit.
Do you get audio from the TV chassis? If not this points even more to a B+ supply problem.
Also check out the circuit breaker if it has one, a lot of the time it goes open and is in the ac from the transformer to the B+ rect. a fuse can sub.

You can do a quick check of the flyback/damper circuit by measuring the voltage at the horiz output plate cap (make sure the cap is disconnected from the tube). I would connect an alligator clip lead from cap to the meter probe with set unplugged. There should be around 400 volts or so if the flyback primary circuit and damper are OK. There is 6kV AC generated at the horiz output tube cap when the set is working right so again make sure the cap is disconnected from the tube when metering the voltage.

To fix the phono, just disassemble the motor, it is very simple, and clean out all the old grease from the motor and the changer mechansism, and re-lubricate.

There may be bad electrolytics in the speaker output circuit on the radio and also check the power supply.

[wa2ise]

Originally Posted by RetroHacker

I don't know what problem the amplifier had to warrent new transistors, maybe he was trying to solve the weak sound issue too.

-Ian

He should have attacked the small electroytic caps. Most if not all of them probably have dried out and drastically decreased in capacitence. That will make the sound "thin", "frail" and kill the bass. Replace all of them, one at a time, and pay attention to the polarity. Any value within 20% of the old value, and equal to higher voltage rating will be fine.

[Adam]

Those big Magnavox consoles are nice looking TVs. That Magnavox looks identical to a TV I had last year. The power supply was bad in mine, both the caps and the diodes. Almost every tube in the set was shorted. It was in really bad condition and after I finally got it to work the flyback melted, so I kept it for parts and junked the cabinet.
My cabinet was a little different but the controls and the chassis look the same (except mine had a remote). If it is the same, it should be in sams 746-3. The corresponding numbers on the set should be either C/U45-(01/02/03/or04)-00.
I've heard those Astrosonic ss radios sound really good once they get working properly. (mine didn't work either, so I never heard one myself)

[RetroHacker]

Yeah - the AstroSonic radio's do sound great - I used to have a Magnavox stereo console that had one. One channel was dead, but man, the other one sounded great (when you could get the controls set so they actually worked, they were pretty worn out). I ended up junking that console, it was in horrid shape - the amp sat around here forever and ended up getting tossed, I shoulda kept it for parts...

The sound does work on the TV, but all that means is that the tuner is getting proper power and is working - all the audio gets fed through the Hi-Fi amp. So maybe the B+ supply has a chance of working. I'll check it. Once I pull out the chassis, I should know more - I just haven't had a lot of time. Maybe tonight after work.

Thanks for the tip about the flyback voltage Chad - I'll try that one too. I certainally hope the flyback is good... I have no clue where I'd find another one.

Originally Posted by wa2ise

He should have attacked the small electroytic caps. Most if not all of them probably have dried out and drastically decreased in capacitence. That will make the sound "thin", "frail" and kill the bass. Replace all of them, one at a time, and pay attention to the polarity. Any value within 20% of the old value, and equal to higher voltage rating will be fine.

Brilliant! I was initially just thinking power supply caps - I've not seen this problem before, and I hadn't thought about that. I don't work on SS stuff all that often, and when I do, typically it's just _dead_ and has a power supply problem. When I start working on the amplifier, I'll start there. Thanks!

The changer should be easy. It's the same changer I've got in my Magnavox Concert Grand, and as such, I've saved them from every junked Magnavox anything I've found, and I have spare motors, idler wheels, and whole spare changers. Obviously, I'll try cleaning it first, but it's nice to know that I've got the right parts, just in case.

-Ian

[Randy Bassham]

That's the U45 chassis, we used to call it the backwards chassis because the HV cage is on the left and the power transformer is on the right. Your flyback has been changed, the original had a black wax covering and was recalled because of a tendency to catch fire if they shorted and arced. I changed a bunch of them. I've got the Magnavox service manual for it. PM me with your address and I'll make a copy of the manual for you.

[Charlie]

I was thinking the same thing as Randy... someone has changed that flyback.

My Maggie B&W console has that same stereo... and mine sounds like crap also. Probably needs new lytics.

That's a beautiful piece of woodwork, Retro! Great score!

[bgadow]

Wow, a long ride but looks like it was worth it! I had been wondering who had gotten this one. I was expecting to see an RCA clone. Great looking cabinet.

[JCFitz]

I'm glad it was saved.I was getting a little worried there would be no takers as Bryan had no room for it and I had no room either.We're both in Maryland and I'm not big into collecting tvs.I got too many jukeboxes,records and old recordplayers taking up room.I love that cabinet.Wish my 1960 Magnificent Magnavox console stereo had a cabinet that mint.It's pretty clean so I think it was taken care of but looks like it got some nicks and scratches from the Salvation Army's handling of it before I bought it.Same color wood as your combo.Those Magnavox stereos do sound great.Mine is tube and sounded great from the getgo.The record changers all get gummed up grease.I disassembled my changer and relubed it and it works like new.Had to get an idler wheel from a donor.Mine was hard as a rock and brittle.Now I'm a little sorry I didn't get that tv.

[blue_lateral]

Great looking set!

John

[kx250rider]

That's an unusual one, and I remember about the flyback catching fire on those. I saw several sets where that happened. Most of the Magnavoxes I worked on had the HV cage on the Right (looking from rear of TV).

Charles

[Telecolor 3007]

I want one of those big stuffs. Those speakers are pergectly of extermineating the manele!

[vintagecollect]

NICE compact color chassis , mostly on a PCB. Looks ahead of it's time , shame fly tended to fry in bad way. I wonder if was due to black wax used(lower melting point?) on fly, haven't heard that much with RCA flys when they went bad?? Replacement fly looks very clean & high quality, a recent repair?? AWESOME set!! Servicing that will be a snap compared to older and larger color chassis. Another great benefit is the use of BETTER capacitors, aren't those Orange Drops? Glad someone saved this classic. That original fly problem was a fluke, but these newer roundies from the 60s have some nice improvemenets over the 50s color sets.

[KentTeffeteller]

Hi,

Magnavox flybacks in that era were weak points. I have changed a few of them myself. I love the Magnavox Astro-Sonic consoles well. I used to have a dingy, white one from 1976 which was wonderful. Collaro made those changers in these. Nice, simple unit which was easy to service. I love roundies!

[Sandy G]

Great lookin' set ! Very glad you got it-& that it's gonna get a new lease on life. Can't wait to see pics of it working...-Sandy G.