Table 3-6. Troubleshooting Chart

Table 3-6. Troubleshooting Chart -Continued

Malfunction

Test

Posible

Correct

Corrective

Checks

conditions

cause

reading

action

transistors if either

one of a pair is faulty.

Inspect for burned

resistors A22R136,

A21R107 or R7. Failure

of any of these

resistors indicates

failure of the high

power sections for

that phase. Repair as

required.

b. Phasing out of

b. Transistors not burned. b. Signals should duplicate b. If one phase has bad

Disconnect the +28 V dc A13 and A14 (fig.-3-1).

signals but the drive

sync.

cable from the pulser at Noise level is lower and transistors check good,

A14E4, E5, and E6.

waveforms should be

disconnect the wire a

from terminals 4 and 5

clean and square.

Check signals at A22

Q110, Q1l1, A21Q5, Q9,

of the associated

Q105, Q109.

interstage transformer

(OA-A2T3, OB-A2T2

and OC-A2T4). If

signals A13 and A14

return to normal, the

high power switch

transistors have failed. If

the signal remains

distorted, the interstate

transformer is defective.

The high power

transistors may also be

bad if the transformer is

burned out. Replace

components as required.

C. Phase locking

c. Two channel Oscilloscopec. Compare the phase c. Check "or broken wires

and repair as required.

required. Disconnect the relationship of A3, A4,

circuit open.

and A5 two phases at a Check for an open

pulser as above.

ding of the inductor

time. Use A5 as the

scope sync. Vp-p may

secondary. It should

vary but phase

read about 100 ohms.

relationships must be

Replace connector if the

secondary is open.

stable.

d. Replace burned

d . Remove the A27 and A8

d. Output tuning

capacitors. Replace the

modules and inspect for

capacitors open

A44 filter if there is any

burned capacitors.

or shorted.

evidence of black gum.

Inspect the A44 filter for

To check for open

any leakage of black

capacitors, disconnect

transformer A3T2 at pin

2 of all three phases.

Check the capacitance

with a capacitor checker.

The capacitance should

be 11 mfd for each

phase. (One mfd is

internal to the A44 filter.

O. Check A22Q101,

a m17.5 V ±l V.

a Use voltmeter at the

a. Vcc regulator

3. NO output all 3 V is 28 V.dc ±1V.

Q102, CR102, CR103.

+ lead of A22C105.

Iin is less than 100

failed

phases.

Replace as required.

ma.

b. +17 volts normal. +2

b. Overload does not

b. Use voltmeter at

b. OverCurrent

exist but A22E13 equals

Volts after overload

A22E13.

timer failure.

2 Volts. Check A22Q113,

foldback only.

Unit is in

A114, and Q115 with a

permanent

VOM and replace as

foldback.

required.

3-17