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Need help with an old motorola tv

I've gone to a radio flea market recently and picked up an old Motorola vt-71 golden view (I think???). It had a bad ballast tube so I built a new one out of resistors but the filaments still wouldn't light up on any of the tubes?? I think its also one of the first chassis types because my ballast tube had 5 filament/resistor strings instead of the 4 that seem to be found on all of the other vt-71's. (the identifying chassis numbers on the wood were all scraped, so i have no idea/) I've also checked each tube and the crt's heater with my bench power supply; they all worked. What else could it be, the set has power, a new (homemade) ballast, tubes with working heaters. What else should I check? Any ideas on how to make this old set work would be great.
Thanks in advance -Ray
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It's hardly complicated - simply a series chain of valve heaters and a few resistors in series directly across the supply - check it with your meter on ohms.

It's pretty well like trying to repair Christmas lights :D
 

unclejed613

Well-Known Member
Most Helpful Member
corroded contacts in the sockets, a bad solder connection somewhere in the series string.... you really need to localize the problem first.... do you have a schematic? if so it should show you what order each tube in the string is at.... pick a tube in the middle of the string and measure from one end of the string to that tube.... if you have a connection, then measure from the other end of the string. if it's open circuit, you then go half way between the middle tube and measure from the end of the string to the 1/4-way tube, and to the half way tube.... rinse and repeat until you locate the fault. it's a lot faster than going through one tube at a time
 

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