Motorola HT 1000 service manual To Remove the RF PA, To Replace the RF PA

Models: HT 1000

1 170
Download 170 pages 52.45 Kb
Page 71
Image 71

reflow, and may inadvertently move. Be careful when performing the following procedure.

Refer to Figure 17 for RF PA nomenclature.

PA Cover

Slab

 

Solder

Leads

Pads

 

Figure 17 RF PA Nomenclature

To Remove the RF PA,

add flux to the leads of the device, and use a soldering iron and pair of

 

tweezers to heat and lift each lead free and clear of its respective solder

 

pad on the circuit board. Use the R-1319 Rework Station and the heat-

 

focus head designed especially for removal of the RF PA. Attach the

 

heat-focus head to the chimney heater. Adjust the temperature control

 

to approximately 415 degrees F (215 degrees C) 445 degrees F (230

 

degrees C) maximum. Apply solder paste to the exposed solder pads

 

under the PA. Place the circuit board in the circuit board holder, and

 

position the RF PA under the heat-focus head. Lower the heat-focus

 

head until it is approximately 1/8”-1/4” (0.3cm-0.6cm) above the PA

 

cover. Turn on the heater and begin the reflow cycle. Heating time

 

should not be less than two minutes.

 

Once the part has reflowed, before trying to remove the PA, carefully

 

lower the circuit board holder as follows:

 

Loosen the thumbscrew on the shaft of the circuit board holder,

 

push the spring-loaded holder down and away from the heat-focus

 

head, and

 

retighten the thumbscrew with the holder in the bottomed

 

position.

 

Grab the PA with a large pair of tweezers and remove it from the circuit

 

board. Let the circuit board cool for approximately two minutes. Then

 

remove the circuit board from the circuit board holder.

To Replace the RF PA;

if necessary, add solder to the PA ground plane on the printed circuit

 

board. Then clean each PA lead solder pad on the circuit board to

 

ensure alignment of the new RF PA. Prepare the sight by using solder

 

wick and a soldering iron to remove all solder from the solder pads.

 

Clean the solder pads with alcohol and a small brush. Dry and inspect.

 

Ensure that all solder is removed.

 

Once the preparation is complete, place the circuit board back in the

 

circuit board holder. Add solder paste flux to the ground plane and to

 

the leads’ solder pads. Once the flux is applied, place the new RF PA on

 

the circuit board, making certain that the PA heatsink sits flush on the

 

board. Position the heat-focus head over the RF PA and lower it to

 

approximately 1/8”-1/4” (0.3cm-0.6cm)) above the PA cover. Turn on

49

Page 71
Image 71
Motorola HT 1000 service manual To Remove the RF PA, To Replace the RF PA