Teledyne Preliminary Troubleshooting Steps, To reset the 4220 software, Occur

4220 Flow Meter

Section 6 Maintenance and Service

To reset the 4220 software:

1.Press Print Program for a record of your program setup.

2.Turn the flow meter off.

3.Hold down the 4 and Exit Program keys simultaneously.

4.While still pressing the 4 and Exit Program keys, turn the flow meter on again. Wait until the display reappears before releasing the keys.

Pressing 4 and Exit Program may leave some values pro- grammed into the flow meter's computer. If you want to remove all programmed entries, hold down 1 and Clear Entry while powering up the flow meter.

The following messages describe serious internal problems, indi- cating service is required:

ROM CHECKSUM ERROR - or -

FOUND BAD RAM - CALL CUSTOMER SERVICE

If these messages appear, call the Teledyne Isco Customer Service Department at (800) 228-4373.

CAUTION

6.6Preliminary Troubleshooting Steps

Do not attempt to disassemble or repair the 4220 Flow Meter (other than changing fuses) unless you are skilled in the evalu- ation and repair of microprocessor-based circuitry. Teledyne Isco recommends no attempt be made to disassemble or repair the printer mechanism or display module.

The electronic circuitry of the 4220 is solid-state and its reli- ability is high. If the unit should fail to operate properly, the problem is most likely a mechanical failure. Items such as a broken or intermittent connections in the power cable or wiring harness or (rarely) poor electrical connection through keypad switches should be suspected.

6.6.1If Serious Problems If you suspect an electronic problem, Teledyne Isco recommends

Occur	that you contact the Teledyne Isco Technical Service
	Department. Contact information can be found on the War-
	ranty page at the back of this manual. Our Technical Service
	Department has trained technicians and specially designed
	equipment necessary for timely, efficient repair of the 4220 Flow
	Meter. If you still wish to attempt repairs, the Customer Service
	Department is available to provide additional advice and infor-
	mation on servicing.

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