SECTION 4
SYMPTOM CHECKLIST
The Symptom Checklist is designed to assist you arrive at a rapid diagnosis for problems.
Each symptom is accompanied by some. possible causes. Instructions for
Disassembly/Assembly, adjustments and/or replacements are on the pages following this
Symptom Checklist.
SYMPTOM POSSIBLE CAUSES REMEDY
Snowy Screen
Switch Box, Power Supply,
Channel Select Switch,
RF Modulator or Cable
Damage
Adjust or replace
(See Page 4-4)
Black/Gray Screen
+5VDC, L4-L8, ANTIC,
CR8, Power Plug, SW1, Y1
Replace
Green/Yellow Screen U27, U1-U9, U12, U13 Replace
Solid Blue Screen U24, Q3, Y1, Q2, Q4, U19 Replace
No Color or Bad Color Bars
VR1 Adjust, U20, U2, U19,
Q3, Y1, RF Modulator
Adjust or replace (VR1
Adjust – Page4-2; RF Modu-
lator Adjust Page 4-4)
No Color Bars on TIA test U19 Replace
No Lights (L1, L2, L3)
LED 3, LED Pin 1, +5A
Power Supply, U23, Q9
Q10, Pin 3, Pin 4
Replace. If problem is LED –
replace the LED Board
No Gray Bars
RF Modulator, Y1, VR1, Q3,
U19
Adjust or replace (VR1
Adjust – Page4-2; RF Modu-
lator Adjust Page 4-4)
Upside down Alphanumerics
or Player Field
U20, U19, U3 Replace
Some Keyboard Keys Fail U24, Keyboard Replace (See Page 4-4)
All Keyboard Key Fail U24, Keyboard Replace (See Page 4-4)
Tones Missing During Sound
or Games
U24, L11, L12
Adjust or Replace
(Adjust Audio Figure 4-1)
Console (Game) Switches
will not Function
U19, U23 Replace
ROM Test Failed U12, U13, U14. U18, U22 Replace
RAM Test Failed U1-U9, U7, U14, U22 Replace
130XE Personal Computer
Field Service Manual 4-1
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