Magnavox Astro-Sonic Sams Info?

I have an Astro Sonic console with television and having a heck of a time finding a Sams or any service docs. All the TV shops I hung around as a kid have closed up and the owners fled to florida. All I can get for solid identification is the model 2C7683 Run-6 serial unknown and all of the internal chassis tags have long turned to dust. Uses the 6JE6 on the horiz out and ultrasonic remote if that helps narrow it down. Set works well but has pincushion and horiz width problems being that its overscanning. HV is around 26KV.
Anyone help out with a Sams number? The earliest Sams catalog I can get is 1981 and doesn't show anything of a 2C7xxx number at all.

Hey anyone remember Marties TV service or Jensen TV in minneapolis?

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[bgadow]

Randy Bassham is the resident expert on Magnavox. Keep the thread active, I'm sure the next time he is on he will help you out.

Good deal I always like meeting others who have a taste for the older established technology. Currently I have the Magnavox plus a Motorola Works in a drawer and a Sylvania that is getting the finishing touches. The Motorola has a strange horiz issue with the black band on the left of the screen even after 2 rounds on the bench, rainy day project.

Anyway thanks for the reply
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[Randy Bassham]

I'm at work now but I'll look it up when I get home and reply back. I'm sure I've got the Magnavox service manual for it....I'm way behind on getting copies made I've promised gotta get busy.....

[Randy Bassham]

Your set was sold as a 1969 model with what Magnavox called Total Automatic Color. It was Magnavox's attempt to lessen the need to keep adjusting the tint control, (sorta worked) but I though it caused people to look kinda orange especially if the TAC switch was pushed all the way to the second position. The set uses the T-940 chassis which is in Sams 1141. I serviced an awful lot of those sets in the 70's, they're good sets but do have a few quirks. Take a look inside of the HV cage and look at the HV rectifier socket # 1 it should have a 3CU3 in it instead of a 3A3, we had problems with the 3A3's filiment dropping and shorting destroying the flyback, then between the socket and the back of the cage there should be a teflon plastic sheet, early runs tended to arc through the rectifier socket to the case and we were supposed to put in the teflon whenever we serviced them, later runs came from the factory with the teflon insulating plastic, make sure it has the heavier wire for the HV rectifier winding, should be a red wire with a couple of turns around the bottom of the flyback, the thin stuff they used tended to break down and arc through, simple problem just get heavier wire and rewind it, if it was turned off before real damage was done. If you have a problem with low contrast it's usually the 1st video tube which is the last tube on the right of the IF board, early runs used a 6LM8 but I can't remember what the later runs used. If you raise the chassis and notice a blob or two of tar that came out of the power transformer don't worry too much about it, they tended to dribble a little in the first month or so of operation, I can't remember ever having to replace a power transformer in one of these sets.

You do know your mags! It does have the 3CU3 in the HV cage as I put it there myself along with the whole set of tubes. I did notice the teflon sheet so I can assume this is the later run set, date codes found on the deflection yoke and convergance yoke show Dec. 31, 1969.... DAMN THING IS ONE DAY OLDER THAN I AM! at least the yokes are anyway.
You mentioned the total auto color and its effects. I noticed this as well and is there a fix? For now its switch off but I like to have things right. My son calls it the "Brady Bunch Effect" but at 19 what doesn't he know...
I am wondering what the failure rate of the "hard to get parts" is like. Flyback physically looks good and the power xfmr has not shed any tar. The only issue I found was the conditions of the solder connections and the pincushion/deflection issues Im dealing with.
Cabinet is in my dads wood shop and we are doing a surface strip to get the decades of heavy cigarette tar off and when everything is done I will post a few pictures.

I did achieve total success with my Sylvania CL818W-2 and works like new. I forgot how good some of these sets actually looked, I'm not much of a fan of these oversaturated colored edgy lined sets of today.

Thanks a million Randy and thanks Audiokarma!

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[TV Engineer]

The radio chassis is probably an R220. A very good stereo chassis @ 25 watts per channel. Does it have the motorized volume control for remote operation, or the 3 step relay?

[Randy Bassham]

Sets that came with the auto tint feature have motorized volume and the bottom two buttons on the hand unit were for volume and were both tan in color. If the set didn't have auto-tint the bottom buttons were green and red and controlled the tint. This set will also have the auto off feature, there is a circuit that uses the sync pulses from the station to hold a transistor in cutoff, when the station goes off the air the transistor conducts and charges a capacitor when the capacitor reached the firing voltage of a neon bulb the bulb fires and causes a relay to close monentarily which pulses the remote off function turning the set off. Nice circuit to have with ultrasonic remote sets since they tended to get turned on by jingling change in someones pockets or a dogs chain collar.

Originally Posted by TV Engineer

The radio chassis is probably an R220. A very good stereo chassis @ 25 watts per channel. Does it have the motorized volume control for remote operation, or the 3 step relay?

Motorized volume control that actually works. 25 watts channel is what I expected but instead found shorted output caps and transistors. I just bypassed the entire amp after the controls and plug wired in a Heathkit AA-111 tube amp in its place along with a stand alone MTS decoder. Gets me about 15 watts/chan with 7 additional tubes with a nice clean sound.

My only complaint of the stereo chassis is its lack of sensitivity. I tested and tried to align the FM section but could only get 4.2uv of sensitivity for 20db quieting and around 7uv to get a good stereo pilot. All the supply rails look good and I really dig that positive gound but no matter what I do I can never get a clean 10.7 IF to the 4th IF amplifier. Are these stagger tuned by chance? From all accounts the FM looks like a standard wideband 10.7 IF with 4 amplification stages, it *should* have gangbusters sensitivity with all of those stages.

One last question and that is does anyone know a good sub pix tube for this set without that damn frosted faceplate? Of all the positives going for this set that antiquated green edged pix is about the worst thing.

Oh Randy: The Sams number was 1144, the 1141 turned out to be an Admiral and something else folder set. Now I need to find the actual TV set to match the service manual!

Thanks guys, anything I can help with?

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[bgadow]

The green-edged crt can be repaired but the process is not for the faint of heart. Should be lots of subs for that tube, though. A late 70s 23" Zenith is a favorite donor of many.

Originally Posted by bgadow

The green-edged crt can be repaired but the process is not for the faint of heart. Should be lots of subs for that tube, though. A late 70s 23" Zenith is a favorite donor of many.

Actually shortly after my post on the CRT I remembered having a mid-70s Works in its drawers Motorola with an excellent black matrix 23" tube that tested perfect so I swapped it in with little difficulty. Actually the only issue was the tension band and the corners of the CRT being slightly smaller than the 25" that came out, used some coax wrap on the brackets and had it done and converged by sunrise.

I did find a process to completly remove the front faceplate on my 18" Zenith and that was suspend the tube face down over a 15 KW load bank and heat it evenly until the frosted glass released from the poly binder that turned out to be the same stuff thats used to laminate automotive windshields. The poly seems to give out around 475 degrees.

By the way who is the Zenith $ervice Saver expert around here? Having issues with a smelly flyback thats not drawing excess current, just boiling the wax in the center. Its a 20YIC37 chassis and my horiz current is on target and B boost is normal. Just let it boil or will it become a fryback soon?

Thanks Guys
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