Elecraft K3
KPA3 Power Connector Replacement
Revision A Review, April 16, 2012
Copyright © 2012, Elecraft, Inc. All Rights Reserved
Introduction
The connectors furnishing high current to the KPA3 module have failed in certain units. Typically the pins on the male connectors become overheated, damaging the female connector and reducing power to the KPA3. This causes an ERR 12V message to appear on the K3s display. Note that this is not the only reason you may see the ERR 12V message. There are many possible causes. Consult your K3 Owner’s manual for details.
The replacement connectors have gold plated pins to ensure adequate current carrying capacity without future trouble.
There are two sets of connectors involved. One carries the current from the K3 RF board to the KPAIO3 interface board and the second set carries current from the KPAIO3 board to the KPA3 power amplifier module. If you are replacing the connectors as a preventative measure, you need change only the male connectors. The female connectors in the K3 are already gold plated. However, if you have suffered damage as indicated by discolored pins or other signs of obvious overheating, you must replace the female connectors as well. It is certain that the female connectors were damaged internally by the heat.
Parts and Tools Required
You will need a temperature-controlled ESD-Safe soldering station, solder, and your normal hand tools such as needle nose pliers and diagonal cutters. In addition, you will need de-soldering tools such as a solder-sucker or vacuum de-soldering tool. Some of the connector contacts served with wide circuit traces which act like a heat sink and may make it difficult to completely remove the solder from the pads with de-soldering wick. A DMM is needed for checking for shorts.
A kit containing the required parts is available from Elecraft. Order KPA3CONMDKT. It contains the following parts:
IMAGE |
DESCRIPTION |
QUANTITY |
ELECRAFT PART |
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NUMBER |
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3X2 pin gold male connector P67B and P68B |
2 |
E620255 |
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10X2 right angle gold female connector J68B |
1 |
E980223 |
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13x2 right angle gold female connector J67B |
1 |
E620144 |
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In extreme cases of corrosion or overheating there may be damage to the connectors on the KPAIO3 interface board (see Figure 18, on pg 10). Female connectors are included to replace them if needed, or you may choose to replace the KPAIO3 board assembly. A replacement KPAIO3 is not included in the kit, but you can order one separately if needed. Order E850271 from parts@elecraft.com.
Elecraft • www.elecraft.com • 831-763-4211
Procedure
A grounded wrist strap and ESD dissipating mat are recommended whenever you work inside your K3. Optionally, touch a bare metal ground frequently while working.
Disconnect power and all cables from your K3.
Remove the nine screws to free the top cover as shown in Figure 1 After removing the screws, lift the cover gently to reach the speaker wire connector. Unplug the speaker then set the top cover aside in a safe place.
Figure 1. Removing the Top Cover.
Remove the KPA3 fan panel as shown in Figure 2 and set it aside.
Figure 2. Removing the Fan Panel.
KPA3 Connector Replacement
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Remove the three screws securing the KPA3 amplifier module to the shield assembly (see Figure 3).
Figure 3. Removing the KPA3 Screws.
Unplug the KPA3 module from the two multi-pin connectors at the rear edge by placing your thumbs under the back edge of the KPA3 board near the connectors and placing your fingers on the heat sink to gently move the opposite edge of the KPA3 up and down (see Figure 4). This will “walk” the connectors apart, freeing the module.
Your KPA3 module may produce a rattling sound when shaken. This is normal. It is caused by ferrite beads sliding along wire leads in the module.
Figure 4. Removing the KPA3 Module.
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Remove the KPAIO3 interface board as shown in Figure 5.
Figure 5. Removing the KPAIO3 Board.
Remove the left side panel (Figure 6). If you have the K144XV module installed, first unplug the remaining coaxial cables and the power cable. Then remove all of the 4-40 (smaller) screws and remove the side panel with the K144XV module attached. If the KXV3 sub-receiver is installed, carefully slide the K144XV module out under the stiffener bar. You may need to lift the end of the stiffener bar slightly to pass the K144XV module under it, but take care not to bend it.
Figure 6. Removing the Left Side Panel.
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Remove the KIO3 Remote I/O Module as shown in Figure 7.
Figure 7. Removing the KIO3 Remote I/O Module.
Remove the KIO3 board as shown in Figure 8. The pony board carrying the audio connectors can remain plugged into the KIO3 board.
Figure 8. Removing the KIO3 Board.
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