IRebuildMarantz: LED Lamps

I get a lot of questions about LED lamp replacement. Here I will show you how to build your own LED lamps and how to replace them in your Marantz receiver. This page will show the generic way to change out the lamps since some models will be slightly different.
To get started, you will need a few things: You will need a number of white and red LED's (number depends on the model of Marantz you are working on), some 1/4 watt resistors, some old fuses, a hot soldering iron and solder, and a vise or some way to hold the LED's while you solder them.
I currently use Chicago Miniature bright white LEDs:

CMD333UWC

I like the Kingbright red LEDs:

L53SRDG

There are many distributors and varying prices so I will leave it up to you to find a supplier. Resistor values I have used are 56 ohm 1/4 watt for the dual LED fuse sytle replacements, and 100 ohm for the single bi-pin style replacements. I use a 270 ohm with the stereo LED for current limiting (protects the MPX IC). If you use different LEDs than the ones I mention above, you should check the current and, according to the device datasheet, determine the best resistor value. The idea is to get the best tradeoff between brightness and current keeping in mind that the LED will last the longest when the current is kept the lowest possible.

The rather narrow beam of these LEDs require that they are adjusted in order to get the most even lighting from them and not create a bright spot. I use a Dremel with a sander bit to remove the LED lens and rough up the exterior of the LED to create a more diffused light.
Once the LEDs are prepared, cut and curl the ends of one resistor and place the LEDs and resistor as shown here at the left. Using your hot soldering iron and solder, very quickly solder each resistor/LED connection.

IMPORTANT: LED's can be damaged by the soldering iron if it is kept on the LED's leads for too long. Try to solder in just a second or 2 to keep this time to a minimum and you can be sure the LED will last a long time.

Now take the ends off some old fuses you have lying about and place them on the ends of the LEDs as shown here:

Once again, keep the soldering time to a minimum.

When done, trim the ends and make the next one until you have number of fuse style lamps you need.

Now that you are a pro at making these, the bi-pin replacements should be a piece-of-cake!
Cut the positive lead of the LED (usually the longest one) leaving just enough lead to curl up to the body of the LED. Do the same for the resistor you are going to use.

The idea here is to get the resistor as close as possible to the LED to keep the overall length as short as possible. Otherwise we end up with a bright spot again.

You will need to make up some red LEDs, too for the Dolby and Stereo indicators. They are made the same way.

Be sure to make up one dial pointer LED as well.

I use heat shrink on the dial pointer LED once it is installed so that there are no issues with shorting. The other LEDs will not require heat shrink if they are done properly.
Now we can install the bi-pins. These will require you to remove the cover of the receiver and get access to the bi-pin lamps.
Heat up both leads at the same time by using your iron tip diagonally and pull the old lamp out. Remove the old solder and insert the new LED. You may or may not have a red LED here, so check it out. Orientation is usually positive (resistor side) to the left (when receiver is facing you).

IMPORTANT: Be SUPER careful not to hit the tuner string with your hot iron or it will be a gonner and it takes considerable time and effort to restring (read: you don't wanna go there!)

Solder in the new LED again being extra careful not to go anywhere near the tuner string then trim the ends.

Now move on to the next one until you are done.

That pretty much covers it. Not as hard as you thought was it?

Additional notes:

The dial illumination LEDs are installed in one of 2 ways. If you are planning on replacing the dial diffuser paper (recommended), remove the front face of the receiver and remove the dial plastic itself. This will allow access to the lamps easily. Use the old diffuser paper as a template for cutting out a new one and reinstall with small amounts of glue when reassembling.

If you just want to change out the dial lamps and not deal with the diffuser, you can go through the top of the receiver at the back of the dial display. There are usually 2 screws on either end of the dial lamp plastic reflector assembly. Remove these 2 screws to be able to pull out the fuse style lamp holder bar. It's a bit difficult to maneuver in there and hemostats or needle nose pliers may help you as you remove and replace the fuse style lamps. Reinsert the lamp holder bar and screw down the ends when done. Sometimes the plastic has deteriorated here and I often have to apply some glue to get everthing solid again. There is no polarity to these lamps BTW.

The LEDs are flexible which allows for adjustment of the actual light beams so that bright spots can be minimized. I find that making them a little "wall-eyed" makes for the most even lighting.

Thanks for visiting and good luck with your LED lamps! Email me if you need help or have any questions.

 

 

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