View Full Version : 1967 Magnavox Imperial Astro Sonic 3 in One


Ronald Hofme
07-20-2017, 09:53 PM
I've been working on a 1967 Magnavox Imperial Astro Sonic Agean Classic 3 in One. I got it in February 2017 & I got it all to Work except for the TV Part. What could be the Trouble? I talked to the Lady who owned it & said the Picture on the
TV just got Darker & Darker Gradually & it just sat in the Courner it hasn't Run for 22 Year's. I had to replace the Turntable it was badly damaged by Children. It has the 2 Button Air Phantom Remote Control which took a while to get up & running again. There is NO High Voltage & all 24 Tube's look Original so where do you think I should start to look for Trouble? It was a very expensive Console in 1967 costing over $1,000.00 New & it was a Special Order model also.

Ron

Electronic M
07-20-2017, 11:20 PM
First off as a moderator please put advise threads like this in the appropriate forum for the type of set being discussed, and not in the classifieds which are for buying and selling (now I have to move your thread to the rectangular Tube TV section).

Second: Some advice to calibrate your expectations. A tube color tv (as I suspect this is) is the most complex consumer electronic device predating home computers. If you want to DIY the repair, prepare to do a lot of research and detective work, and to find and make available technical info on the set. Many problems have a lot of potential causes that vary with the exact chassis design and shot gunning repairs (throwing parts at the wall hoping something will stick) usually harms more than helping.
It is generally best to have some experience doing capacitor replacement and general restoration on tube radios before thinking about tackling a TV.

If you plan to service it yourself you need to get the schematics for it. Look for the TV model and chassis number and search the sam's photofact index for it. You may need to post a want ad, but make sure you have the chassis number in the ad. (IIRC Chassis is more useful in maggies since some models were unique)

Since it probably has been dormant for a while measure the B+ voltages and compare to the schematic. If any B+ voltages are more than 30% off (especially if low) the power supply lytics may have gone bad from age/sitting dormant.

By no high voltage I assume you mean 25KV CRT voltage and not B+. Original tubes mean either a low hours set, or a high hours set that as not electronically maintained...In either case test them all on a good quality tube tester before digging in too far.

If B+ if good you can troubleshoot the horizontal. First make sure the horizontal output tube is not redplating (the plate of the tube should NOT glow in the dark, only the heater should). If the tube redplates it indicates one of several circuit faults and should not be run for more than 10 continuous seconds of plate glow....If ran longer the tube will be damaged and or have it's life shortened, also other rarer parts are put at risk.

If the tube is not red plating can you draw an arc from the outer winding of the flyback to the blade of an un-grounded, well insulated screw driver? If you get 1/2" or more of an arc but none at the CRT hv connector suspect a bad HV rect tube.

If there is no arc from the fly the next step is to measure the control grid and screen grid voltages on the Horizontal output tube and compare them against those listed on the schematic. Report back the results and we will help you interpret them.

If the grid is substantially less negative (more positive) than the schematic specifies then the H oscillator circuitry or it's coupling to the output is defective.

Troubleshooting is a game of comparing what is to what should be, knowing signal and power flow paths and where issues on them point to, then following that and repeating on a more detailed level until a defective part(s) is identified.

zeno
07-21-2017, 10:19 AM
Does the TV have sound ? You should get a waterfall sound from it.
If not its probably not just no HV but a power supply problem.
Thats usually good news BUT on a combo with remote there is a lot
more to it.
Start by checking fuses, reset the breaker, look for anything else
amiss. One common problem on those was on/off switches. They used a
gang switch & a tab would break off one of them & not switch.

Get your chassis number & post it. Its a little tag somewhere on
the chassis. Usually starts with a T. example T915-00-ab. The
format varies......
If you order a Sams manual it MUST have all sub folders also if
there were any ! But try us first, Sams are overpriced.
Models on Maggys are ONLY good for cabinet parts.

73 Zeno:smoke:
LFOD !

Findm-Keepm
07-21-2017, 11:17 AM
If you kindly share the model number or chassis number, a great many of us with Sams Photofacts can help.