displat CIRCUIT boaad

Fig, /fa| 8/oc/t d/agram of decimal point driver circuitry of the Model 2000 DMM before modification.

shorting the input leads and punching up the 10.0-volt ac range.

If you refer to Fig. 1(a) and compare the simplified diagram with the schematic in your manual, you will see that tne range and function switches drive the decimal points directly off the -¡-6.0-volt line through R49 (150 Ohms), Fig 1(b) shows a block diagram of the circuit after modification. The modification requires only three garden-variety PNP transistors and three Vi- or Vi-Watt resistors. You do not have to cut or modify any of the traces on the PC boards.

Fig. 2 shows the actual schematic of the added t ir-cuitry. The transistors drive the decimal points; the switching arrangement on the DMM main PC board js now near ground potential and carries only the small base current needed to drive the transistors Although a small PC board would have allowed a neat installation, I did not think it was necessary for so few parts, In the following steps, refer to the diagrams of the PC boards in your Sabtronics manual as well t

original CI «tu il

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