RCA 18V100 service manual 9a appears on screen immediately, and Tester, Board must be replaced

is indicated on the TV screen; if there is no trouble, the

cartridge sets up a test for the two keyboards.

NOTE: The Test Cartridge requires substitution

of the power unit during test. Use the special

500mA power unit (see Parts List) instead of the

original power unit.

1.Press and hold "Clear" button on Studio II console. In- sert Tester cartridge into slot while holding "Clear" button.

NOTE: Insert cartridge into console with label

side toward "Clear" button. Follow label directions concerning removal of conductive rubber strip covering the plug.

2. Release "Clear" button. A pattern similar to that of Fig.

	9a appears on screen immediately, and Tester	begins its
	scan of the system (indicated by the black streak moving
f	through the white field in the lower half of the pattern). If the
	pattern fails to appear or a pattern other than that shown
	appears, a faulty chip is indicated. Replace PC board.

In about 1 1 seconds, the first scan is complete. The display

shifts to the pattern shown in Fig. 9b with a white streak scanning a black field. This scan takes another 1 1 seconds. At

the end of the second scan, the system changes the pattern on

the lower half to a series of transient vertical white lines on

black and then a series of black lines on white. This sequence

takes about 2 seconds. At the end of this short sequence, the

pattern again shifts- to that illustrated in Fig. 9c. This indi-

cates all memories operational. A digit or digits appearing in

the "checkerboard" pattern in the center of the screen, as

shown in Fig. 9e, indicates chip failure in the PC board and

the board must be replaced.

r	If the checkerboard appears as in Fig. 9c, touch the keys
	- one at a time - of Keyboard A, and then Keyboard B. As
	each key switch closes, the digit on screen should change to a
	checkerboard square. (If any digit remains on screen after key
	actuation, the keyboard is defective and must be replaced
	(see Page 11). When all key closures are complete (indicating
	CATV			STUDIO	TV
	CO-AX	CATV		SELECTOR
		MATCHER		SWITCH	RECEIVER
				BOX
				ANTENNA
r				TERMINALS
	Figure 6.	Selector Switch Box Connects Between CATV Cable
		Matcher and Home Receiver
	ANTENNA		TV -«	nc/i
	TERMINALS			»- STUDIO II
		£1
					o
			-T®~L
					TO
			STICKY TAPE		CONSOLE

Figure 8. Adjust Receiver for Sharp "Freeway" Display

(d)Operable Keyboards and Electronics

mmmm^m

(e)Bad Key A7 and Digital Failure

Figure 7. Selector Switch Box Figure 9. Tester 1 Screen Patterns