STAR*TECH Journal
June 1987 (12)
Exicty Identifies Most Common
Problems: Power Supplies
and will not stay aligned.
By Exidy Customer Service
Frenont, california
8. 'Ihe screen has only yellow and blue
bars and multi-colored dots.
The rrost cornnon customer calls received
over the past year relate to the Power
supply and the Optics. Below are some
helpful hints for identifying these type
of failures.
9. Something smells funny, sparks, or
srrokes.
'!he :EOvER SUPPLY accounts for the vast
majority of customer calls. '!he voltage
should be checked regularly to verify that
it is between 5.25V and 5.35V at the
connector on the audio board.
If this level cannot be reached, then
disconnect the PCB's from the power supply
and measure the resistance across +5 and
GND connections. You should see between 6
and 60 ohms. If there is a short to
ground, get a qualified technician to
service your boards. If the resistance
reading is ok, then chances are the power
supply has failed. Occasionally a power
supply will adjust to 5.3V while under
load, and still not provide the required
current. '!his is evident by excessive AC
ripple (above 70 millivolts) on the 5 volt
line.
Fower supplies can account for a wide
variety of symptoms. Here are.some of the
rrore memorable ones:
•
10. locks up once or twice a day.
11. Gives a different diagnostic error
every time it's p:,wered up.
'!he Optical Electronics account for the
next most corrmon customer call. 'Ihese will
be covered in the next issue.
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3. Picture waivers and goes away \ltlen
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