1. Decimal Point Placement: DATEL ships the DMS-EB-AC/DC with

all decimal point solder gaps (SG1, SG2, SG3 and SG4) open. To

enable a specific decimal point, close its respective solder gap with

solder. When reassigning decimal places for subsequent applications,

remember to open any previously closed solder gaps.

Close SG1 for 1.999 (DP1)

Close SG2 for 19.99 (DP2)

Close SG3 for 199.9 (DP3)

Close SG4 for 1999.9 (DP4 on DMS-40LCD)

2. Span (Gain) and Zero (Offset) Adjustments (See Figure 3): Loca-

tions are included on the DMS-EB-AC/DC to add user-supplied potenti-

ometers R4 and R5. Recommended values for these two components

are as follows: R4: 2KΩ, 10-20-turns; R5: 50KΩ, 10-20 turns. Vishay's

T93YA series potentiometers are suitable for this application. Make

sure to use only RoHS-compliant components and solders when mak-

ing modifications to DMS-EB-AC/DC.

Once installed, these components permit the span and zero adjust-

ments described in the following sections. R4 provides span adjust,

while R5 applies and offset voltage to (-) IN LO (J1, pin 2).

Using Potentiometer R4 for Span Adjustment (DMS-30PC and DMS-

30LCD Meters Only)

1. For DMS-30-1, -2, and -3 models (+/-2V, +/-20V, +/-200V ranges):

Configuring the DMS-EB-AC/DC for span adjustment is simply a

matter of installing potentiometer R4, opening SG13, and then clos-

ing SG8, SG11, and SG12.

2. For DMS-30-0 models (+/-200mV ranges): Span adjustment re-

quires that you open SG8, SG11 (if closed) and SG13 and then close

SG7, SG and SG12. Then install R4.

Adjust span as desired. DMS-30-1, -2, and -3 span adjustment

range is typically +10% and –5%. The DMS-30-0 has a much wider

span adjust, however, it should be limited to ±10% for optimum

accuracy and stability.

Using Potentiometer R5 to Apply a Positive Offset to Pin 12 (-) IN LO

1. Open SG14 and close SG6.

2. Install 50K potentiometer R5.

Potentiometer R5 applies a stable, positive dc-offset voltage to

the meter’s IN LO terminal. This offset voltage has a range of 0 to

+1.2Vdc, measured with respect to TB1 terminal 2 (LO). It can be

used to null (or cancel) the effects of an input whose zero level is

not exactly zero volts. For example, adjusting R5 allows the display

to read “000” with an input whose lowest level is slightly above

zero volts. Please note, R5 cannot compensate for inputs whose

zero level is negative (i.e., if TB1 HI is more negative than TB1 LO).

3. Measuring Input Voltages Greater than 1.999Vdc (Use DMS-30-

0 or DMS-30-1 Only): If possible, the resistors used for R1 and R2

should be ±1% metal-film types with TCR’s less than or equal to

100ppm/°C. More information on selecting 1% resistors can be found

in Application Note 14.

CAUTION: Do not apply inputs greater than +/-250Vdc.

1. Open SG10. For applications in which input voltages exceed

±100Vdc, also cut the 2 adjoining traces.

2. Configure the DMS-EB-AC/DC for span adjust using the procedure

previously outlined.

3. Calculate values for R1 and R2 as follows:

A typical value for R1 is 1MΩ. The sum of R1 + R2 should be

between 50kΩ and 10MΩ.

R2 = (FSI x R1) / ( |Vin| - FSI)

Where:

FSI = The attenuated voltage between the meter’s (–) IN LO and

(+) IN HI pins (pins 12 and 11, respectively) needed to achieve the

desired display readings

Vin = Input signal at TB1 terminals 1 and 2, disregarding polarity

APPLICATIONS

12

1

R3

SG3 (DP3)

SG2 (DP2)

SG1 (DP1)

SG9

SG11

SG6

SG10

SG14

SG7

SG8

SG13

SG4

SG12

TB1

TB2

HI(+)

LO(–)

AC LO

AC HI

12

12

DP4

Figure 2. DMS-EB-AC/DC Board

DMS-EB-AC/DC

100-264Vac Power Supply

Accessory Board for DMS-30PC/LCD Panel Meters

www.murata-ps.com

MPM_DMS-EB-AC/DC.B01 Page 3 of 4