Seca 727 Series Service Manual page 12

Seca 717/727/728/737/748/757
7. Fault description: Signal transmitter on
model 748 not working.
To check the microprocessor output, IC 520:
- Start the scale
- A voltage of 5 V must be present at pin 34
- Load the scale with 5 kg and restart it
- " UP " flashes
- Relieve the scale by at least 1 kg
- 0 V must be present at pin 34 for approx. 1
second
- If this is not the case, replace resistor network
519
or the microprocessor, IC 520.
Check transistor 324:
- A voltage of approx. 0.2 V must be present at
the
collector of transistor 324
- Load the scale with 5 kg and restart it
- " UP " flashes
- Relieve the scale by at least 1kg
- 5 V must be present at the collector of
transistor
324 for approx. 1 second
- If this is not the case, replace transistor 324
Check transistor 325:
- A voltage of approx. 12 V (or 9 V if the scale is
operated on rechargeable batteries) must be
present at the collector of transistor 325
- Load the scale with 5 kg and restart it
- " UP " flashes
- Relieve the scale by at least 1 kg
- 0.2 V must be present at the collector of
transistor
325 for approx. 1 second
- If this is not the case, replace transistor 325
- If the signal transmitter still does not work,
replace
the signal transmitter
8. Fault description: Scale does not display the
correct weight
Check the slope and adjust if necessary, see
manual adjustment instructions:
seca 727: No. 30-34-00-448
seca 737/757: No. 30-34-00-484
seca 748: No. 30-34-00-446
9. Fault description: Scale displays "EEEE" after
starting
Check fuse 450 or soldering jumper 450 and
replace if necessary.
Check the load cell connections on the main
board.
Check the zeropoint and adjust if necessary, see
manual adjustment instructions:
seca 727/728: No. 30-34-00-448
seca 717/737/757: No. 30-34-00-484
23.04.97 - Jen
seca 748:
Blatt 3
Description of faults
No. 30-34-00-446
30-34-00-437 Index G