In this and the next couple issues I'11 try to help with your repair of 1st generation RCA DSS receivers. This info will cover models DRD101,102, 112,212,203,213 and the GE branded GRD112.

A factory service manual, available from Morgan Aerospace or most RCA parts distributors, should be at hand.

The switch mode power supply is a primary source of trouble and easiest to diagnose and repair. It supplies, through one large plug (J4010), all voltages needed by the receiver. The pin-outs measured from chassis (cold) ground:

• If the power supply pulses off and on, unplug J4010 to verifl over-current loading by receiver. ·
• .If the +2 1 .5v is incorrect, suspect CR4014;
• If the +15 and +5v are incorrect, suspect CR4012;
• If -5v is incorrect, suspect CR4013 and C4018;
• If the +5v is low, suspect L4004 or if the +5v is high, suspect CR4022 trace to R4020.

Check C4002 for venting. Check Q4001 resistance: Drain-Source = 1.7Mohm, Gate-Source=9.7Kohm, Drain-Gate=1.7Mohm. Also check Q4001 heat sink insulator for short. If R4018 is open, suspect C4003 shorted.

The most common part failures in the power supply are:

Dead: F4001, R4001, U4002, R4025, Q4001, C4002, U4001, L4004.

Pulsing on and off: CR4021, CR4020, CR4008, U4001, C4004.

Note: Many 1st generation receivers are now becoming available in a non-working condition and are worth about $30-$35 each. If a tuner, power supply, or access card module can be salvaged, they are worth it.

Till next time, Gene