View Full Version : Help - my mint 1977 Magnavox Console


GinoRoth
09-20-2012, 10:55 PM
My wonderful mother passed several years ago and I just moved her beloved Magnavox 25" Console into my home - had to hire piano movers to do it. It was purchased in October 1977 and I found the bill of sale, she paid $1751 for it back in the day and that was a fortune! She really treasured it but mainly used the turn table so the TV, Stereo and 8-Track was hardly used. This set is in mint condition every way and I found all of the documents and manuals that were delivered with it. I hooked it up to my AT&T Uverse box, set the STAR SYSTEM selector for channel 03 and it lit up the most bright, clear and beautiful color picture as it had always done despite its 35 year age.

But.. after 3 weeks of flawless TV operation, there is a problem. This is a T 995-02 chassis with a pull down main board and module cards. The clock and channel number that used to appear on the screen no longer displays. There are fine white horizontal lines on the screen that are spaced wide apart, maybe 6 or 7 of them. The picture is somewhat distorted and the colors are bad - flesh tones look red all colors look too dark. I tried to correct this by turning the horizontal hold on the back of the set but that did nothing. The Brightness, Contrast, Tint, Color and Sharpness controls on the front panel of the set all work and change the picture but none of them correct the problem. A switch on the back of the set turns on the Videomatic feature which by pressing the Videomatic Button on the front of the set is supposed to return all picture settings to factory presets - this did nothing but turn down the brightness so I turned it off again. Thinking that the tube was Gaussed, I got a Degausser on Ebay and tried to demagnatize the picture tube - not much effect. So, I rolled the set out from the wall and removed the back cover - barely a speck of dust found it looked so factory fresh. I inspected all the boards to see if there was a blown Cap. but I found no problem there with a visual inspection. I found a slow blow spring type fuse on one of the boards but it looked fine - no blackened glass.
I measured 24vdc on pin 27? going to the picture tube from the Chroma Osc. board and the schematic said that was spot on.

Can anyone help point me to what board or component that I should check? There are a lot of memories in this set and everything else works fine so I am not giving up until I get it fixed. First guy who leads me to success gets kudos sent back to this board.

bgadow
09-20-2012, 11:39 PM
Welcome to VK! This set WILL work right again...with some patience, folks here will get you walked through it. Sounds like you have enough experience in electronics to follow good directions. I'm mostly going to let others help out with this, but I would start by concentrating on the video board (assuming it uses a seperate one). Were it me, I'd start by just rocking that board back and forth in its socket to make sure the contacts are good. Then I'd probably replace the electolytics in that circuit. Just my thoughts.

Eric H
09-21-2012, 12:06 AM
Welcome!
I was going to suggest removing and reinstalling the boards, Modular sets were notorious for bad connections back in the day, much less 35 years later.

Other than that Bryan's idea to recap the video board sounds like a good place to start, I would check the transistors on it as well.

It could be an issue with the Chroma board too, if you could post a picture of it playing it might make it easier to pin down.

It sounds like you might have a picture that's all Chroma and no Luminance, though I think the picture would disappear if you tuned the color off in that case.

I recently found (and returned) a low hours set with the same or similar chassis, it worked great I just didn't need it. Wish I had it to offer parts from.

magnasonic66
09-21-2012, 08:19 AM
I just wanted to give you a warm welcome, as a gigantic Magnavox nut. What a beautiful set, I'm glad it didn't go to an estate sale or thrift store! And I hope that beauty is up and running again soon.

holmesuser01
09-21-2012, 11:26 AM
I've always loved the big home entertainment systems. Magnavox was always a favorite of mine.

You might want to check the ground connections, and the condition of the solder at the pin connectors at the modules, and also, the solder connections at the plugs on the modules. I saw alot of low-use chassis with bad soldering, just like the high-use ones.

I had this same Star system chassis on a customers set for years. It had some issues with board connections, but ran well until lightning ran into the set due to his satellite dish not being grounded. The tuner module had its covers blown off. What solder in there? I should have taken pictures. It was so weird to see.

Bruce

GinoRoth
09-21-2012, 02:47 PM
Thanks to all you guys and the great tips you gave me. I cant wait to roll this set out again from the wall so I can start pulling out cards and cleaning up the contacts. I will have a look at all the grounds and solder too. I probably should look at all the caps again as I take the cards out to get a better look at them - just wish I had an ESR meter to do a better job of checking these caps out. I forgot to mention in my original post that when the set first powers up the picture and color is very good but within 20 seconds or so, it goes bad. So if heat creates more resistance that might mean I have a leaking cap on the board or a slot pin is pulling away from its socket and not making good contact - we used to call this condition a dirty open when I was a tech at AT&T. It would not surprise me with all the jolts and shocks this cabinet took on the journey to my house. Hopefully I can do this later today or tomorrow and I will post again.

DaveWM
09-21-2012, 04:59 PM
try some cooling spay to isolate the problem.

wkand
09-21-2012, 05:01 PM
Search YouTube, and you will find several homebrew ESR meter ideas. I am building one of them as we speak, but have not completed it yet. Best of luck to you!

legenbass77
09-21-2012, 09:52 PM
Awesome set! I have a '77 Magnavox console with a T995-02 chassis too. Does your remote work very well? That's the only trouble with mine, hopefully I'll find a good one someday. Good luck getting yours going again!

GinoRoth
09-22-2012, 02:58 AM
What a great board you guys have here, I am getting a good response to my little problem. I was not able to work on my set today maybe tomorrow and I will try to take a good picture of what the problem looks like on screen before I try any of the suggestions. Legenbass77 my remote works perfectly but like I said, this set has had very little up time.

Speaking of low up time, my parents also had one of the large old Airline Radios in the nice wood console. It was a combo AM - FM Radio and Phonograph. I'm looking at it right now sitting here in my man cave. Its a model 84WG-2714F. My dad modified it by taking out the old phono and large speaker that was mounted to the back of the front door. The door used to pull down from the top with hinges at the bottom but my dad put hinges at the side and turned the interior phonograph area into a little mini bar. The radio is still in there and I got the Sam sheet on it earlier this year thinking that I would get it working again one of these days. It still looks every bit as good as the Magnavox TV, not a scratch on the cabinet and this thing must date back to the late 1940's. They bought this at Montgomery Wards and inside of the cabinet I have found The original envelope holding the Owner's Guide, Service Manual plus all the little cards and notices that the store had fixed to it. The service manual is quite detailed with specifications, chassis diagrams and a complete replacement parts list. Back in the day they sure knew how to treat a customer and you sure don't get this level of information when you buy a radio today. I should post this to the old radio thread with a picture. Wonder if I should recap it or leave it as is?
Thanks guys.

Username1
09-22-2012, 07:51 PM
Its possible its just a bad connection like already mentioned. One good way to check for a bad connection is to run the set with a mirror so you can see the picture, and move all the boards around and push on the main board with a wood dowel. Don't put a lot of pressure, and don't over push on the plug in boards. If yer worried about a shock put a good leather glove on, use only one hand, put the other one in yer pocket. You should see the picture go back to normal when you move the parts closest to a possible bad plug, or bad solder joint. you can even tap, or hit stuff wit the wood dowel. Dowel should be pencil thickness, or a little larger, and about 20" long. I would not recap anything that will just cause you problems. Fix this problem first. Be sure its not a bad connection before you go on to replace parts. Sets with plug in boards - always check for bad connection plugs, contacts, solder joints first, its a known weak spot. Stay away from the high voltage section, you problem is most likely not there. Don't turn everything, a gremlin didn't turn all the turnie things over night to screw wit you.

GinoRoth
09-22-2012, 08:49 PM
Hey Squirrel Boy-some good advice coming from you, Thanks; and to DaveWM I like the idea of the cold spray and I would like to try that especially now that I have monkeyed with this set and made it a little worse. Boy do I need a drink! The first pick below is an example of what my picture problem looks like before I did anything today. You can see that the color is way off but the broken lines all over this pic must be a result of some strobe effect between the set and my camera because I do not see this distortion on screen. Then, I unplugged the set and started pulling the cards I had good access to and brushed across the pins with a small wire brush to clean them, gave all the Caps a good visual and then replaced the card back on the main board. I did the same thing with any sockets that were plugged into the main board. I then inspected the solder points on the main board and they all look fine. I then plugged the set back in and turned it on. The picture came back on as before but the whole image is now pulled over to the right side of the tube by a few inches. I could not find any adjustment on the front or back of the set that would allow me to center the image on screen. I then pushed out the service lever (the other pic below) and what should be a solid line is actually the colors of the picture tube being fired like an arc rather than in a straight line. I don't know how to adjust this if that is even possible. The colored lines being displayed in this "service mode" did not show up well in my picture but on screen, they are sharper and not blurred like you see on in my picture. In addition, the problem with the Channel number display and clock not appearing has not resolved with what I have done so far. So, it seems that I have some problem with the module that controls the channel/clock display and another problem with what ever is controlling picture image. Its interesting to note that when the set is first turned, the picture is perfectly centered and not bad but this only last about 10 seconds now then I get all the color and picture distortion. Does anyone know where I can get or order replacement module cards for the Horizontal Osc. and Chroma board? This is a T-995-02 Chassis. Thanks Guys

bgadow
09-22-2012, 10:51 PM
Do you have the part numbers for the modules you need? Might be on the chart inside the cabinet, if not it will be in the Sams Photofact. There is a good chance somebody on here has spare boards. I had a bunch from that era but finally passed them on to somebody else, might have been somebody on here? Anyway, they are out there.

Bill R
09-22-2012, 11:43 PM
First things first. The clock and channel indicator is generated by a board in the tuner cage. The fact it stopped working may indicate you have a low or missing B+ voltage. See what voltage should operate this card and be sure it is there. Your other problems, bad color, over biased CRT causing retrace lines, and bad video are all caused by different boards. I would bet they also use the same B+ supply as the clock. The shrinking picture also indicates a power supply problem. Check or replace the main filter caps. If one is leaking it should be warmer than the others. This one thing could cause all your problems, and may also cause the picture to be ok for the first few seconds until the capacitor heats up and draws the supply voltage down. I wouldn't do anything to the boards other than reseating them until you know there is no power supply problem. I would also pull the clock module and see what the picture looks like without it. It may have a shorted component pulling down one of the supplies. Good luck these are great sets.

GinoRoth
09-23-2012, 01:40 AM
Thanks Bill your information sounds very helpful to the problem. I knew something was heating up quick and causing this all to happen. I'll get on it this week and let you know what happens.

Eric H
09-23-2012, 03:00 AM
Interesting, the first picture almost looks like you have all the Color information but none of the Luminance, i.e. Color but no B&W picture under it.

The second is a collapsed Vertical Sweep, either the Vertical module didn't get put back in correctly or you bumped the Service Switch which will put it in a flat line, turn down the brightness or you risk burning a permanent line in the screen!

Bill R
09-23-2012, 11:32 AM
Could be something as simple as a bad video module. I will need to find my service manual. I think loss of video will cause loss of clock and channel display.

holmesuser01
09-23-2012, 03:34 PM
I dont think you need a horizontal module, either. Your HV is running and the picture is there.

Username1
09-24-2012, 07:54 PM
With bad connections/solder problems out of the way, I agree with bill, see why the tuner indicator is not on, it could be one of your power sources, like a 12v, or something like that. Also the first picture posted looks like color, but no luminance information, like already mentioned. So hopefully there is a open resistor, bad cap, or bad solder connection somewhere in the low voltage power sources. It may not be what most refer to as B+, but one of the lower supply voltages. But again, all the turnie things are not currently the problem.