Magnavox Astro Sonic Magna Color model 1C7606 - Videokarma.org TV - Video

pac.attack76 · #1 01-31-2015, 09:41 PM

25" Color tv doesn't turn on. suspect tube with white spot to be the reason but correct me if I'm wrong. Turntable barely turns but is complete right down to the needle and 45 rpm adapter. Tuner section and speakers work great. All for $25. Couldn't pass it up. Cabinet is a pecan finish. I could tell work had previously been done probably several years ago. some newer tubes in place and 3 older ones lying inside the cabinet. that and a couple empty tubes of contact lube or something. Model number appears to be 1C7606. Serial is 1332518. Any ideas as to what year model this is and where i should begin repairs?

rca2000 · #2 01-31-2015, 10:16 PM

I do not see even ONE picture !!

pac.attack76 · #3 01-31-2015, 10:34 PM

Hahaha. I'm trying. I'm barely online and everytime I submit a pic, it stops halfway. Give me a chance. I just posted this and I'm still working on it.

Olorin67 · #4 01-31-2015, 11:10 PM

That tube is definitely bad... The question is, why.? A capacitor may have failed causing the tube to overheat. You need to find out why before you pop in a new tube. If one cap is old enough to fail... There are probably others about to go.

pac.attack76 · #5 01-31-2015, 11:20 PM

Quote:

Originally Posted by Olorin67

That tube is definitely bad... The question is, why.? A capacitor may have failed causing the tube to overheat. You need to find out why before you pop in a new tube. If one cap is old enough to fail... There are probably others about to go.

I thought so. So in changing these caps, where should i start? Not sure on the location of all of them and it would be nice if there was a kit but i doubt there is. will probably have to order by piece or something. where's the best placevto order for something like this?

Electronic M · #6 02-01-2015, 12:11 AM

I'd put another tube in and watch it after turn on in a dark room to see if the plates start to turn red if so pull the plug IMMEDIATELY (unless you want to damage the tube). Sometimes tubes loose vacuum (which is why the getther turned white) due to mechanical shock, and other factors like age, so I'd try another tube carefully before digging in. The caps in the H osc. and those between it and the H output grid would cause the output tube to red plate (which is another thing that may have brought it down to air) as would a dead osc. tube.

pac.attack76 · #7 02-01-2015, 12:14 AM

Quote:

Originally Posted by Electronic M

I'd put another tube in and watch it after turn on in a dark room to see if the plates start to turn red if so pull the plug IMMEDIATELY (unless you want to damage the tube). Sometimes tubes loose vacuum (which is why the getther turned white) due to mechanical shock, and other factors like age, so I'd try another tube carefully before digging in. The caps in the H osc. and those between it and the H output grid would cause the output tube to red plate (which is another thing that may have brought it down to air) as would a dead osc. tube.

Sounds good. I'll check into that. Anyone have any idea what year model this is based on the model number?

pac.attack76 · #8 02-01-2015, 01:05 AM

Were these set up for remote control and if so, could someone supply me with a pic of the right one for this model? I'd like to find one.

zeno · #9 02-01-2015, 07:24 AM

First thing is to find the chassis number, very
important on a maggy. It will be on a small tag.
Format is like T-991-02-AA.
There is also a different one for the stereo thats usually
hard to find.

73 Zeno

joemama99 · #10 02-01-2015, 09:35 AM

From the knobs and changer,you can date this one between 1966-68.The remote would be a 2-button bellows type.To tell if you have a remote,look for a couple of wires that go from a solenoid on the turntable to a small chassis covered with cardboard-type material.

DaveWM · #11 02-01-2015, 11:33 AM

would be a good idea to get the tubes in the sweep circuit (damper/shunt/HV rec/horz out) as they take a beating. Also I would get an extra horz osc tube just in case, as losing that can take out the horz out.

Cap wise, assuming its been powered up (TV) then no point in trying to reform the filter caps, they are either ok or blown now. Typically sets of this era do not need massive recapping to work, besides the PCB's can be cooked and fragile so no need to stress them with needless recapping.

I would get a new horz out, monitor the cathode currrent (make sure it does not go over 220ma) and try it out. If the can caps do not get hot they are prob not shorted (but could be open). A base line run with the replaced tube would be the way to go.

pac.attack76 · #12 02-01-2015, 12:13 PM

I'll check into all this. I'll see if I can Locate chassis number. I did notice this has front display below the screen for channel display and to the right of that, something that looks like an eye or led maybe. Inside mounted behind there is a metal piece with two wires leading to it. I'll have to order tubes and get to work on the. I imagine the turntable needs an idler wheel.

Jeffhs · #13 02-01-2015, 12:54 PM

Quote:

Originally Posted by Olorin67

That tube is definitely bad... The question is, why.? A capacitor may have failed causing the tube to overheat. You need to find out why before you pop in a new tube. If one cap is old enough to fail... There are probably others about to go.

The tube might simply be weak. It amazes me how you guys always seem to jump to conclusions, when eight out of ten TV failures (in the vacuum tube era) were caused by nothing more than weak or dead tubes. When I used to restore old TVs I found in the trash in my home town, I found that a simple tube replacement more often than not got the set working again. As an example, I once had a 1963 Zenith K-2739 23" TV that was missing all but two tubes (HV rectifier and CRT) when I found it in 1969 near the end of the street I grew up on. I replaced all the missing tubes, and was rewarded with a TV that worked very well. Then I moved in 1972 and was forced to give it up (no room for a console where I moved; long story and OT). Didn't have to do anything under the chassis to get it working as close to normally as I could at the time. The set probably would have worked a few more years if I had kept it.

Olorin67 · #14 02-01-2015, 01:05 PM

When the sets were fairly new.. a lot of failures were bad or weak tubes.. but after 50 years..the capacitor failure rate is now a lot higher, at least for paper based caps and electrolytic. Caps go bad with age, tubes don't. most of the "bad" tubes I find are because a capacitor failed and changed the bias on the tube making it run too hot., or shorted filter caps that made the rectifier tube act like a fuse...

pac.attack76 · #15 02-01-2015, 05:24 PM

Isn't that tube in question, a 6JE6A? What brand replacement would be recommended, original Magnavox?