PC2002M LED Conversion for Meter Lights

miklemke

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I recently acquired a non-working PC2002M. One of the problems was the meter lights were all burned out. Rather than replacing them with regular light bulbs, I installed LEDS. It was relatively simple.

The bulbs are feed with 12 v DC. I used a Linear Regulator to convert that to 3.3 v. The Mouser part number is 595-UA78M33CKCSE3.

12 - 3MM flat top white LEDS were used for the lighting. They operate at 3.2 to 3.4 V. They fit perfectly into the rubber bulb sockets. I acquired them from ebay at about $5.00 for 100 pcs. You could also use blue or green LEDS if you want a different color, or warm white for a look that is more like the original.

The attached pictures show the tools and parts needed.

The steps are:
1) Remove the bulb PCB from the amp. (You could skip this, but it was much easier with the board removed.) You have to desolder the supply lines.
2) Remove the rubber bulb sockets. They just pull off of the supply pins.
3) Remove the bulbs from the rubber sockets. Just bend the wires straight and pull out.
4) Insert the LEDs. Watch the polarization. The sockets have STANLEY embossed on the back. Just put the anode on the "S" side as a point of reference.
5) Bend the LED leads as shown in the picture. In this configuration, they wrap around the voltage supply pins.
6) Reinstall the sockets. Put the anodes on top (the "S" side of the socket).
7)Take some frosted scotch tape and place on the top of the meters. They are clear plastic. If you don't do this, you will get shadows from the lights. The tape serves as a light defuser.
8) Make a deflecting mirror as shown in the picture. I bought a flexible plastic mirror sheet at a craft store. It was easy to cut with scissors. It is 3/4 inch high by the width of the meter. The notches hold it in place. Fit the mirror between the front panel and the top pins of the light PCB. This will have the mirror at about 45 degrees and will deflect the light down onto the face of the meters. (This is optional, but greatly increases the amount of light.)
9) reattach the PCB with the three screws.
10) solder the Regulator onto the PCB. The common ground (middle lead) goes into the hole from the original black supply wire along with the black supply wire. The + out lead goes into the hole of the original yellow supply wire. The Yellow wire is connected to the + in lead of the regulator.

You're done. Enjoy.
 

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Made one modification to the above. A 2 ohm 1/2 watt resistor was added to drop the voltage to 3.0 volts. The resistor was soldered to the PCB in the original yellow power supply line hole and then connected to the regulator + output lead.

Without the resistor, I did have some LEDs burn out. The resistor seems to have solved the problem.

The regulator puts out 3.3v and the LED's were rated at 3.2 to 3.4 v. Too close for comfort.
 
After cleaning out the corrosive glue, removing the corrosion, replacing the bad components, and doing a complete (except the two main power caps) recap, the amp has worked perfectly.

Avionic and JBLMAR helped tremendously by giving critical advice as I did the repairs. Thanks guys!!! Couldn't have done it without your help.
 
Do you have larger pictures? The thumbnails actually pull up thumbnail sized attachments when clicked on.

Does the voltage regulator get warm or hot because of having to knock down 9 volts and about 1200 ma or so (12 LED's at around 10ma each)? Does it need heat sinking?

Edit: Hmmm, the regulator sources 500ma, so you must be running <5ma each LED or two regulators?

In some cases, I might consider adding some small caps at the input and output of the regulator.
 
Last edited:
Hello,
I have done ,on my two pc-2002m, the meter led conversion too.
It's not harder. I'vekept the original pcb and just throw the stanley bulb, kept the original support. I've used 3mm leds, and a 1/4 watts resistors.
I'have done the complete recapping of one of my three pc-2002m with the goods advices from Miklemke!!:thmbsp:
 

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Just the one regulator and one 2.2 ohm resistor. It's not too hot and no heat sink.

Unfortunately, no larger pictures.

Have 100's of hours with no problems.
 
Do you have larger pictures? The thumbnails actually pull up thumbnail sized attachments when clicked on.

Does the voltage regulator get warm or hot because of having to knock down 9 volts and about 1200 ma or so (12 LED's at around 10ma each)? Does it need heat sinking?

Edit: Hmmm, the regulator sources 500ma, so you must be running <5ma each LED or two regulators?

In some cases, I might consider adding some small caps at the input and output of the regulator.

Did the math: 12 LEDS @ 22mA = 264mA, about half of the rated 500mA of the regulator ===> no heat sink required.
 
Do you have larger pictures? The thumbnails actually pull up thumbnail sized attachments when clicked on.

Does the voltage regulator get warm or hot because of having to knock down 9 volts and about 1200 ma or so (12 LED's at around 10ma each)? Does it need heat sinking?

Edit: Hmmm, the regulator sources 500ma, so you must be running <5ma each LED or two regulators?

In some cases, I might consider adding some small caps at the input and output of the regulator.

Did the math: 12 LEDS @ 22mA = 264mA, about half of the rated 500mA of the regulator ===> no heat sink required.

Yep, I completely screwed up the math assigning 12 LED's at 100ma each!! That would be a nice flash and then need replacements. At 120ma, would be even lower power dissipation.
 
I don't understand why to use a regulator. You can do an array and use a simple resistor to keep the current through the diodes below the maximum allowed
 
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