Spectra AL20M manual Adjusting the Instrument, Service Request

Taking an Angle Measurement

1.Set up the tripod so that it is over a hub.

Note: Make sure the tripod is stable and the tripod head is relatively level.

2.Hang a plumb-bob from the plumb-bob hook on the tripod. Note: Make sure the plumb-bob is over the hub.

3.Attach the instrument to the tripod.

4.Center the plumb-bob over the pin in the hub by varying the length of the tripod legs or by shifting the instrument on the tripod.

5.Accurately align the telescope to the first target using the sighting guides and a horizontal tangent knob.

Note: The first target is a known point.

6.Set the horizontal rotation ring to 0.

7.Accurately align the telescope to the second target and read the angle.

Adjusting the Instrument

Circular Level

1.Set up the instrument.

2.Center the bubble of the circular level using the leveling screws.

3.Turn the telescope 180° (200 gon).

4Check to see whether the bubble is still centered in the circle.

If it isn’t, eliminate one half of the error with the leveling screws and the other half with the two adjustment screws for the circular level.

5.Repeat the process until the bubble remains centered when the instrument is turned.

Line of Sight

a2		b2
a1		b1
		B
A
a2 = 2.423	b2 = 1.462
+b1 = 0.936	-d	= 1.487
d = +1.487	c	= 2.949

1.Set up the instrument half way between two points (A and B) that are 30 to 40 m apart.

2.Take a reading at point A (a1 = 2.423 m) and another one at point B (b1 = 0.936 m).

3.Subtract b1 from a1 to get the difference between the points (d = +1.487 m). Make sure you note whether value d is a positive or negative number.

Note: Because the distance from the instrument to each of the points is equal, the difference in elevation is correct even if the line of sight is out of adjustment.

4.Move the instrument and reset it up so that it is about 2 m behind point B.

5.Take another reading at point B (b2 = 1.462 m).

6.Add b2 to d to get value c (1.462 + 1.487 = 2.949 m).

7.Take another reading at point A (a2).

8.Compare value c (2.949) to a2. If the line of sight is correct, both numbers should be the same. If they differ by more than

4 mm, reset the grade rod on point A and turn the crosshairs adjustment screws (unscrew the cover to expose them) until value c (2.949) is centered in the crosshairs.

Caution: The upper and lower adjustment screws are counter-screws and must not be set too tightly.

9.Repeat the process until the line of sight is correct (c and a2 are the same).

Specifications	– 9 –				– 10 –
	AL32A	AL28A	AL24A	AL28M	AL24M	AL20M
Magnification	32X	28X	24X	28X	24X	20X
Dampening	Air	Air	Air	Magnetic	Magnetic	Magnetic
Accuracy*	+/-1.0mm	+/-1.5mm	+/-2.0mm	+/-1.5mm	+/-2.0mm	+/-2.5mm
Leveling Accuracy @ 50m	0.5mm	0.7mm	1.2mm	2.5mm	2.5mm	2.5mm
Telescope:
Aperture			30mm (1.2 in.)
Telescope image			Erect
Field of view angle			1⁰20'
Shortest focus distance			0.60m (1.97 ft.)
Stadia constant			100
Addition constant			0
Dimensions (L x W x H):
Instrument		103 x 190 x 135mm		(5.2 x 7.5 x 5.3 in.)
Case		170 x 280 x 190mm (6.7 x 11 x 7.5 in.)
Weight:
Instrument			1.6 kg (3.5 lb)
Case			1.25kg (2.75 lb)

*Standard deviation according to DIN 18723 on 1 km of double leveling

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Service Request

To locate your local dealer or authorized Trimble Service Center

outside the U.S.A for service, accessories, or spare parts, contact

one of our offices listed below.

North-Latin America	Asia-Pacific
Trimble / Spectra Precision Division	Trimble Navigation Singapore PTE Ltd.
8261 State Route 235	80 Marine Parade Road, #22-06
Dayton, Ohio 45424-6383	Parkway Parade
U.S.A.	Singapore, 449269
(888) 527-3771	+65 6348 2212 Phone
(Toll Free in U.S.A.)	+65 6348 2232 Fax
+1-937-203-4419 Phone	China
+1-937-482-0030 Fax
	Trimble Beijing
www.trimble.com/spectra
	Room 2805-07, Tengda Plaza,
Europe	No. 168 Xiwai Street
Trimble Kaiserslautern GmbH	Haidian District
Am Sportplatz 5	Beijing, China 100044
	+86 10 8857 7575 Phone
67661 Kaiserslautern
	+86 10 8857 7161 Fax
GERMANY
	www.trimble.com.cn
Tel +49-(0)6301-71 14 14
Fax +49-06301-32213
Africa & Middle East
Trimble Export Middle-East
P.O. Box 17760
JAFZ View, Dubai
UAE
+971-4-881-3005 Phone
+971-4-881-3007 Fax

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Notice to Our European Union Customers

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Recycling in Europe

To recycle Trimble WEEE, call: +31 497 53 2430, and ask for the ÒWEEE associate,Ó or

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8261 State Route 235

Dayton, Ohio 45424-6383

U.S.A.

www.trimble.com/spectra

N324

© 2012, Trimble Navigation Limited. All rights reserved. Reorder PN 1211-0200B (03/12)