Best sets for a newbie to work on

[jshorva65]

I would tend to agree that the electrostatic sets are the simplest designs and a good starting point for a newbie, but I would tend to recommend one of the 7" Admiral sets or other models that used a power transformer. Series heater strings can be a pain for a newbie. If one of the heater string's bypass capacitors is bad, the set could blow tubes. Also, the lack of a power transformer in a set can be a safety issue unless an external "isolation" transformer is used during troubleshooting.
I've always hated working with ballast tubes, also. The Admiral 19A1's use a straightforward parallel-heater circuit and transformer-rectifier-filter B+ supply. Those Admiral 19A1's have B+ current demands that aren't much higher than those of a conventional radio and use a single 5Y3 rectifier tube. Some basic electronics knowledge (experience with reading a schematic and some practice with a few old radios) is essential before tackling ANY tv set.

After working on one or two electrostatic models, the best electromagnetic models to move up to are the RCA 630TS and its clones (Fada TV30, 799, 899; Crosley 307TA, 9-408; AirCastle A-1000, A-1001; RCA 8TS30) The chassis layout of these sets is very logical. RCA also published quite a bit of information about this model. The 7th Edition of Kiver's Television Simplified includes a fold-out schematic and discusses the RCA 30-tube chassis in great detail. The 630 has a pretty hefty power supply, though, so it's essential to clear up any conditions that could potentially overload the B+ supply before installing the dual 5U4's in the circuit. It's also essential to have access to a Variac and an AC ammeter when working on these sets. Power the set down before reaching into the chassis for any reason. Connect a test probe lead to one end of a 470K/10W resistor, connect a 0-500V DC voltmeter across the resistor, and connect a clip-lead to the other end of the resistor. Connecting the clip lead to the chassis, discharge the electrolytic capacitors by touching the probe to the "+" terminal of each one EVERY TIME you power the chassis down before working on any circuitry and keep the probe against the capacitor's terminal until the meter reads 0V. Start with the input filters on the +300V and -100V sources, since these two supplies feed all the other B+ sources. The energy stored in the filter capacitors of the B+ supplies in this set can give a nasty shock long after the set 's cord has been unplugged. It's even possible to operate the set with several tubes removed for troubleshooting purposes. I recommend installing the 6BG6 and 5V4 tubes LAST to disable the 9kV supply until everything else is working correctly and the waveform of the sweep signal that's being supplied to the 6BG6's grid is correct. Making sure that the correct voltages and waveforms are present before installing the Horizontal Output and Reaction Scanning (Damper) tubes minimizes the possibility of excessive current flowing in the delicate windings of the sweep circuit's inductive components (width coil, linearity coil, flyback transformer and deflection yoke). Although the 630TS and its clones use 30 tubes and lots of support components (resistors, capacitors, etc.), they're not as terribly complex as their component-count implies. It's a lot like Algebra, in that it's easier to follow the steps that are involved in reaching the end result when all the work is shown in a straightforward manner without shortcuts. Here's a block diagram of the 630 and its clones to illustrate the point.