Teledyne 4220 Fuse Replacement, F1 5 amp., fast blow, F2 5 amp., fast blow

4220 Flow Meter

Section 6 Maintenance and Service

Note

If you disassemble the flow meter for servicing, you will also remove the aluminum chassis covers to access the circuitry. Always replace these covers when repairs have been com- pleted. The covers protect the circuit boards and also reduce signal emissions that could interfere with the operation of nearby electronic equipment. For the same reason, do not remove any of the ferrite beads or alter the wiring harnesses inside the cabinet in any way.

Figure 6-6 Lifting the Flow Meter from the Case

6.5.2 Fuse Replacement	With the flow meter chassis out of the cabinet, you can locate and
	change fuses. The fuses are located on the printed circuit board
	directly behind the keypad. There is an aluminum cover over this
	board. Remove the cover by pressing against its surface with the
	palm of your hand and then pulling downward on it with your
	fingers. A plastic catch under the cover holds it in place. The
	fuses are labeled F1, F2, and F3. The proper size for each of these
	fuses is:
	F1 - 5 amp., fast blow
	F2 - 5 amp., fast blow
	F3 - 2 1/2 amp., fast blow
	Always replace a blown fuse with one of the same value. Using a
	larger value fuse could cause serious damage to the flow meter or
	to its power supply. Replace the protective cover, making sure the
	two ears on top of the cover slide into the mating slots on the
	chassis. There should be a noticeable snap when the plastic catch
	re-engages the cover.

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