E C O P H Y S I C S Troubleshooting
CLD 780 TR / July 2000 139
10.2 Electrical test points
To improve access to the electronic test points loosen the two screws and
swing up panel on which the circuit boards are mounted as shown in Fig.
3.1.
The position of each checkpoint is indicated on the component layout dia-
grams at the end of this section.
Power supply board (PONOX TR 780 V2.5)
(see Fig. 10.1)
Terminal
TP 1: Mass flow controller output signal
TP 2: Temperature of inlet heater 1
TP 3: Temperature of inlet heater 2
TP 4: +5.18 V
±
2 % (ADC A/D+)
TP 5: Instrument temperature
TP 6: Analog ground
TP 7: -15 VDC
±
5 %
TP 8: +15 VDC
±
2 %
TP 9: +5.1 VDC
±
3 %
TP 10: Digital ground
TP 11: +17 VDC ground
TP 12: +17 VDC +3/-1 V (unregulated)
TP 13: Input voltage +20/+30 V
TP 14: +12 VDC
±
5 % (internal auxiliary supply)
TP 15: Input voltage ground
All temperature measurement circuits, the 8-channel A/D converter of the
microprocessor, the 3 analog outputs and the high voltage supply to the
PMT are driven by +15 VDC. The PMT preamplifier requires in addition
the -15 VDC supply.
LEDs
D 10: +15 VDC OK
D 11: -15 VDC OK
D 13: +5.1 VDC OK
D 15: +17 VDC OK
WARNING!
Before performing any maintenance with the covers removed, the
mains power connector MUST be unplugged from the instrument. Re-
pairs and adjustments, which must of necessity be made with the in-
strument powered-up, may only be performed by trained personnel
who are aware of the dangers involved.
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