Mitsubishi "Blinking Green Light" Repair Procedure (Page 2 of 3)
Categories: Televisions and Projectors
For this repair you will need a Phillips screwdriver, a 15 or 25 watt soldering iron, a desoldering tool (recommended), and four electrolytic capacitors. For the optional fan replacement you need a PC cooling fan, zip ties, foam tape (or weather stripping) and a 12v AC to DC power adapter. Note: The cooling fan is not required provided you replace the capacitors with Caps having a 105c high temp rating.
I recommend replacing the original (bad) 1000µF, 16V, 85ºC capacitors with Panasonic 10,000 hour, Radial Polarized, 1000µF, 35V, 105ºC high temp capacitors. The Panasonic Part Number is EEU-EB1V102. The capacitors may be purchased from a local electronics repair shop or online at digi-key.com. The Digi-Key Part Number is P13126-ND.
If you require a soldering iron, I recommend Radio Shack's 15 Watt Soldering Iron, Part # 64-2051 or the 25 Watt Soldering Iron, Part # 64-2070. Radio Shack also has a desoldering tool, Part# 64-2060, which you may find helpful in removing old solder from the connections, without damaging the board. A basic 11 piece Electronic Tool Kit, Part # 64-2803A may also be of value. The cost for each of these tools is between $10 and $20. Similiar tools are also available from Lowe's, Home Depot or Wallmart.
This is a fairly simple repair for those with a little soldering experience.
Start by unplugging the TV. Disconnect the coax and digital audio cables and remove the rear panel.
Remove the plastic panel mounting screws and set the panel aside.
If you are going to install a fan, position it on the right side of the shield (as seen from the rear) and mark its outline with a pencil. It is easiest to install the fan with the shield removed from the TV, but by marking its mounting position first, you will avoid placing the fan on a part of the shield that has an obstruction. The DM guide partly covers the capacitors that need cooling and the metal tray under the CRTs also restricts fan placement.
Remove the four (4) screws that secure the DM Module. For the left side screw, it may be easier to pull out and set aside the PWB-DEMOD board. It is a small vertical card just to the left of the DM and has a broad copper grounding spring. This will simplify access to the left side DM shield mounting screws. See the pictures below:
Left side of DM Module
Front side of DM Module
Right side of DM Module
Unplug the USB and Firewire cables from the top of the DM, as well as the cable that runs from the front input jacks to the connector on top of the terminal board. Unscrew the grounding strap from the top of the doubler shield.
Remove the 2 screws in the plastic bracket that holds the DMÃƒ Module in place. After removing both screws, pry the plastic piece away from the support piece to which it is mounted.
The DM Module and the shield are removed vertically. In order for there to be enough clearance, the chassis needs to be pulled toward the rear of the TV. All the electronics are mounted on a tray that can slide back like a drawer to make servicing easier.
Remove the board slide, which is a narrow fiber board that stretches the width of the TV above the rear of the chassis and shields the light box from scattered light. It is held in place by a long black screw on either side of the TV. Use caution as the board may fall when the screws are removed.
Undo the wire ties on the cables going to the front of the TV. You will need slack in these wires as you slide the chassis out. You will also need to unplug some of the connectors on the shorter wires. Remove the screw (a) on the edge of the chassis and screws (b) on the xx813. See diagram below:
Release the chassis lock tab on either side of the chassis. The tray may be a bit hard to slide, so alternately tug on the left and right edges to rock the tray rearward. Go slowly in case you've missed freeing a wire bundle. Pay attention to the large red anode wires and other cables on the right hand side as they are clipped to the frame of the TV. Pull the chassis back until the DM shield will clear any obstructions above.
Remove the screws holding the DM shield. (Note: Do not use a power screwdriver on these screws as it is very easy to strip the threads.) There are two on top of the shield, two in the rear base, and one in the middle of the base on either side of the shield. The DM shield can be snug and hard to pull up. Gently rock the shield front and back while applying upward force. You may want to hold down the board below (DTV-TUNER) to avoid disturbing the ribbon connectors to the signal board. The DM itself also comes out straight up, but it is not nearly as tight.
Remove the DM Module by pulling it straight up (toward the top of the television). DO NOT pull it at an angle. The DM Module is connected to the circuit board by 4 sets of pins.
Once the pins are free from the onboard connectors, continue pulling straight up. There is a plastic guide that makes it necessary to pull the DM Module straight up and sliding it over the plastic guide.
With the DM Module removed and positioned, as shown in the photo below, remove the 2 screws located next to the USB and IEEE-1394 jacks and slide the DM circuitboard out of the metal case.
The next and most important task will be to carefully remove and replace the 1000µF, 16V, 85ºC capacitors with 1000µF, 35V, 105ºC capacitors.
CAUTION: Handle the DM circuitboard by the edges to avoid static damage. If you hold the DM with the components facing you and the external connectors on the left, you can find the capacitors in question in a cluster on the top right corner of the board.
Here is what a typical capacitor failure looks like:
The top of the capacitors shown above may only have a slight bulge, but they have indeed failed.
Desolder and replace all of the capacitors at the same time. When inserting the new capacitors, pay close attention to the polarity. The rear of the board has the positive terminal labeled and the longest lead is positive. The capacitor body has the negative terminal marked by dashes running down one side. All the capacitors have the same orientation:
Insert all four capacitors as close to the board as possible. The Panasonic capacitors are 4mm higher than the stock capacitors and there is very little extra room inside the shield. If properly installed, the DM Module case will fit over the DM board during re-assembly.
The picture below shows the underside of the DM board after the capacitors have been removed.
With the BAD capacitors removed, thread the new capacitor leads through the holes in the DM board. Ensure that you have the positive and negative leads on the capacitors threaded through the proper hole. With the capacitors in place, maintain pressure to firmly seat the capacitors against the circuit board and carefully solder each connection. It will help considerably if someone provides assistance during this very important soldering step.
Replace the original 1000uF, 16V, 85C capacitors with Radial Polarized 1000uF, 35V, 105C Capacitors.
If you are going to install a cooling fan, do so now. Once again, if you have used capacitors with a 105ºC temp rating, the cooling fan is not required or recommended. If installing the fan, stick some foam tape or adhesive weather stripping to each corner of the fan. This will minimize fan vibration noise and provide the fan with some clearance from the shield. The shield has a thin ridge that runs diagonally and prevents the fan from sitting flush, but the foam tape will allow the fan to straddle the ridge.
Place the fan on the pencil lines you drew earlier and secure two diagonal corners of the fan with small zip ties through holes in the shield. The zip ties are flat and their low profile will allow the shield to slide over the DM board without getting caught. You can run your fan from a 6v power supply to minimize noise, but test it first since not all PC fans will spin up with just 6v.
For individuals with the Mitsubishi WS-55859, WS-55909, WS-65869, WS-65909, WS-73909 or other Mitsubishi models with seven (7) of the 1000uF, 16V Capacitors on the DM Module instead of four (4), the two photos below may provide a visual orientation when looking at the DM Module circuit board. In this case replace all seven of the original capacitors with those having a rating of 1000uF, 35V, 105C.