SB1004 - Fuse Replacement And Application Of Heat Sink To 5.8V Switching Regulator

RELEASE: 7 July 2006
BY: Dustin Jones, Design Engineer

This service is recommended for all Venue receivers
shipped prior to July 21, 2006. When running 4 or more
receiver modules, the 1.5A poly fuse may trip and the
switching regulator may overheat.

NOTE: This modification should only be performed by a qualified technician

WARNING: Disconnect the power supply from the unit before removing the top cover or performing any service on the unit.



1. Remove the Top Cover

Unscrew the 6 screws noted with a phillips screw driver. With a bit of fi nesse, take the top cover off by lifting the cover up and then rearward (toward BNCs). The front
panel has a lip that fi ts into a wide notch on both sides
of the cover, so the cover cannot be lifted straight off.


2. Locate the Fuse

The fuse is located roughly one inch rearward (toward BNCs), and one half inch toward the center of the PC board, away from the red power button on the front panel.


3. Check the Value of the Fuse

The value of the fuse is embossed on the top. “X250” indicates that the fuse is 2.5A and does not need to be changed. A 1.5A fuse will have “X150” or something other than X250 embossed on it.


4. Remove 1.5A Fuse

Note the orientation of the fuse. Using two soldering irons, remove the 1.5A fuse by heating both solder pads of the fuse and sliding the fuse off the pads once the solder fl ows. The fuse may come apart into two pieces if the solder between the fuse’s metal contacts and the fuse element fl ows. It will not matter since the fuse is to be discarded.


5. Install 2.5A Fuse

Installation is simply reverse of removal. Place the new fuse onto the solder pads in same orientation as the one removed. Heat both solder pads until solder fl ows.

Warning: heating too long will cause the solder between the metal fuse contacts and fuse element to flow, and potentially shift the contacts. If the contacts short out, the fuse will not work!

Verify that the solder bonded to both contacts of the fuse and the PCB pads, and that there are no solder “bridges” to any other components in that region.



1. Locate the 5.8 V Switching Regulator

The regulator is located in the same area as the fuse. It is roughly 3/4 inches closer to the shield housing in the center of the PC board. Refer to the photograph for the exact location.


2. Apply RTV Sealant

Note: Read and follow all directions and warnings on the package of RTV Sealant before applying.

Apply RTV sealant to the top surface of the regulator. Use only enough sealant to ensure complete surface coverage.


Apply sealant to the bottom of the bent end of the heat sink as shown in the photo at right:



Position the heat sink over the regulator as shown. The small end of the heat sink should lay on top of the regulator, and the bent end should be adhered to the PC board.

Warning: When the heat sink is mounted, it should not come in contact with any components other than the top surface of the regulator or the PC board.

Press down firmly on the heat sink to distribute the sealant evenly and ensure maximum heat transfer and adhesion.

Note: Allow sealant to cure in accordance with the directions on the package. Keep the Venue unit
level until sealant cures.



3. Install Top Cover

Slide the cover back onto the chassis by sliding the front notch over the front panel lip, and then lowering the cover. Verify that all screw holes match up, and install the 6 screws with a phillips screw driver.