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27. Troubleshooting the AKB Circuits
CRT elements, improper G2 cutoff or intermittent components, or connections on the IK return line (rare). Verify
G2 cutoff and adjust if necessary. If G2 was set too low, this may have been the problem. Measure the DC
voltage on all three cathodes. If one or two of the cathodes measures less than 170V, it is weak and is the cause
of the intermittent problem. On projection televisions, the blue CRT will be the most likely to cause this problem.
It usually experiences low cathode emissions first because it is driven harder than the red or green CRT.
If all three cathodes measure 180V or more, suspect an intermittent CRT short. Carefully tapping on each neck
can sometimes locate the short. Getting the customer to describe what the picture looks like when it blanks is
also helpful although they are not always accurate in describing the color. HINT: The green CRT in a projection
set is the most likely to have shorted elements. Since it is pointing straight up, it is more prone to particles falling
and becoming lodged in the gun structure. Pay close attention to the customer complaining of pink, reddish, or
purple colors before the picture loss. This helps to verify a potential G1 – G2 short in the green CRT and is the
most common. Any complaints from the customer regarding bright flashes of red, green or blue indicate an
intermittent heater to cathode short.
