Memotech Limited MTX 500, Service Manual

Page: 32 / 78

28
SYMPTOM 2
When power is switched on: Blank screen - no humming
sound.
a)
Cause of Trouble
Faulty video board
Check Point
Check to see if you have control G note
Repair Method
1 If control G note is present video board is
faulty-Replace video board.
b)
Cause of Trouble
Blank screen with no control G sound
Check Point
Check +5v -5v +12v 0v
Repair Method
1 If the +5 voltage is absent, 2nd stage
fuse has blown.
2 If +12v and +5v are absent check both
regulators and associated circuitry.
c)
Cause of Trouble
Blank screen with no control G sound
Check Point
If above voltages are present check 4Mhz Xtal -
Also check RESET circuit
MTX Service Manual