Figure 3-1. SCR Waveforms

TM 11-6130-413-40

Corrective Action

Probable Cause

Malfunction

Item

Check timer switching by starting with the sus-

Defective timer switch contacts.

Unit skips from Charge 1 to Charge 2

pected timer set about 10-15 minutes CW from

without discharging; or does not move

the 1 hour mark. Then start the cycle. Turn the

to next phase.

pointer manually very firmly and steadily to the

one hour mark. If the transition is satisfactory,

proceed to do the same thing but this time

"teasen the contacts by hesitating and even re-

versing the motion slightly as the knob is moved

to the end point. If the contact or the cam is worn

out, the resulting contact bounce may cause the

circuit to jump a phase or go into reset.

NOTE

In practice, the discharge timer does not

transfer on timer operation -it either=

EOD before or after the one hour contact.

As a result, its contacts seldom operate at

a time when transition is possible.

EOD circuits inoperative.

Check voltage on battery at end of Phase 1 (imme-

All batteries pass discharge test.

diately after PASS light cornea on). If it is less

than 18.05 ±5% (for 19 cells) or 19 ± 5% (20

cells) then EOD is switching in at too low a volt-

age.

a. Blown output fuse F2 (not the

a. Replace F2.

Batteries do not discharge; or no control

problem if unit charges).

of output. (Refer to paragraph 3-4d.)

Replace PCB(A1) and forward to Depot for further

b. Defective circuit board.

repair.

Check procedures; check battery voltage and/or

Operator error or electrical noise

Unit stops in middle of a phase

line voltage connections.

or bad connection activating

error detection circuit.

NOTE

If printed board is suspected refer to table 3-1 for normal voltage and readings on a functioning assembly.

Figure 3-1. SCR Waveforms

3-6