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Old 11-08-2008, 12:05 PM
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TheReeler TheReeler is offline
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Changing Pioneer RT-707 direction lamps for leds

Today I was working a Pioneer RT-707, putting some grease in the capstan motor and adjusting the fly wheel when both direction lamps burned. It's rare that both lamps burn at the same time, but I think that this happened because they were in their last hours, and after manipulated the deck, putting it up, down... etc, finally the filaments broke.

Fortunatelly I had some leds left at home, so I began to replace both direction lamps with leds. The voltage to the lamps is about 26VDC, so a balast resistor is needed in serial with each led. I used 5mm width leds, that enter perfectly in the hold.

In a first time I tried a 1.3Kohms. 1/4 watt. After testing, it got too hot, so I tried a 2.2 Kohms. and with more wattage. Tested that first one led with it and all was working well.

Here is the procedure I followed to change the direction lamps with leds.

**Click in the images to watch the big version

1- Remove the deck cover. Four philips screws in each side and three more in the upper.

2- Remove the front panel. Two philips screws and three more in the bottom. Remove the pots knobs of MIC and LINE controls. Also the pinch control knob. To remove the front panel now, both pinch roller must be pushed up manually and with care, pull the panel.

3- Both direction lamps are in a small black socket. To remove it, unscrew the two philips screws.

Each lamp is inside his hole and can be removered simply pulling the lamp from their wires.

4- Solder the balast resistor to the cathode of the led (in the image is shown the first resistor that I tried). Use a simple tester to know which wire will go to the cathode and which one to the anode.

5- Put the led inside the original socket

6- Solder the wires to the led and the balast resistor

Here is another pic with the final balast resistor selected, 2.2 KOhms.

7- Solder the other direction led.

8- Test both direction leds.

9- Put some electric tape in the chasis where will be hold the leds socket, to make a dielectric layer so that nothing wrong happens if some wire of the new leds touch the bottom part of the socket once it has been put in its original place

10- Put the leds socket in its place with the two philips screws and test the work

11- Put the front face and the cover in their original places.

That's all folks!
Old 11-08-2008, 12:26 PM
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4tified 4tified is offline
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Well, I don't have a pioneer RT-707, but I just wanted to say very nice step-by-step guide, with pics even! Anyone should be able to do this.

Old 11-08-2008, 01:51 PM
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Scorpion8 Scorpion8 is offline
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Very nice, as changing lamps to LEDs is almost universal in methodology. Think we'll make this one a sticky.
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Old 11-08-2008, 02:05 PM
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Nice work Reeler. Another one for the maintenance reference section
Old 04-23-2009, 02:16 PM
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Perfect! The forward lamp on my 'new' 707 is out. Soon as I'm back to normal (wrist surgery yesterday), I'll do it up. Thanks for the pix.
Old 06-03-2011, 11:32 AM
Big Bill Big Bill is offline
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Very helpful!

Thanks for the post, it helped tremendously. I found good results using the 2.2K resistors and 5mm green LEDs (20mA 40mcd). Radio Shack part number# 276-0022.

Thanks again, Bill!
Old 06-03-2011, 12:52 PM
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retrokeeper retrokeeper is offline
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I'll do mine when I get around to checking out my 707..thanks for the info & instructions! Rob
Old 09-12-2012, 06:56 AM
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jleon92f jleon92f is offline
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Nice repair procedure, I will do this when I go to change my lamps, one is burnt out now.

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Old 08-07-2014, 11:55 AM
kevman kevman is offline
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anyone know the specs for that resistor? how much wattage ? I see 1/2 , 1 and 2 Watt resistors at Radio Shack.
Old 08-07-2014, 12:51 PM
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Skywavebe Skywavebe is offline
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You just need to know some of ohms law to figure this out. I did one out of necessity not too long ago and I used 3mm LED that were expanded with heat shrink tubing to make then stick in the holders. my purpose is to get the lamps up more forward where the original filaments were. Perhaps this
was no matter but my resistors were like 1.2K. Of course it all depends on what LED you are using and it's maximum voltage and I rating.
I use the Vs- Vled max to get the resistor voltage drop required and 26 Vdc was present and Led max was 2.7V so 23.2 was the drop and error on the side of better the LED could draw 20 mA so 23.3/.020 is 1165 ohms. So I selected a 1.2K resistor that was 1/2 watt. Now the power calc- the
P=I^2 x R so .0004 X 1200=.48W so the 1/2 watt resistor should do. I put the resistor in line with the wires to the LED and covered the bare areas with heat shrink, The resistor itself is not conductive and the did not get that warm. They were plenty bright and these were the White point source LED I bought for meter lighting experiments a while back by the 100 quantity on E bay. I stock White, Blue, Yellow, and Red in 10mm, 5mm and 3mm LED's. it is good to be prepared when you need to do a project like this. Yes, I have thousands of resistors is stock too all values.

There are color lenses in the buttons and so the white will work as well as the green or maybe be brighter.
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Old 08-07-2014, 03:14 PM
kevman kevman is offline
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Thanks SAM, so I think I got it down

My LED specs are Forward voltage: max 3.0, IF=20mA

So that transalates to 1150 ohms of resistance and power .46w

So a 1.2k Ohm resistore with 1/2 power will do it.

Old 08-07-2014, 07:38 PM
kevman kevman is offline
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For anyone that wants to do this here are the parts I picked up from Radio Shack

Item# 226-022
RadioShack 5mm Green LED

Resistor 5PK:
Item # 271-1120
1.5K ohm 1/2W 5% Carbon Film Resistor pk/5

These specs seem to mate together based on the calculations. I'll report back when I get to test this out.
Old 08-09-2014, 10:50 AM
kevman kevman is offline
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I know that the Resistor must get soldered to the cathode side of the LED. But on the RT707 is there a polarity to be considered when attaching the LED to the unit ?
Old 03-02-2015, 11:00 AM
JVRaines JVRaines is offline
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Originally Posted by kevman View Post
I know that the Resistor must get soldered to the cathode side of the LED. But on the RT707 is there a polarity to be considered when attaching the LED to the unit ?
Yes, absolutely. If you connect it backwards, the LED won't light. Use a voltage tester to determine which wire is positive and connect it to the anode (long leg, round side) of the LED. The resistor can go on either side.

I just performed this repair with some 3 mm white LEDs from Parts Express and a 2.2 KΩ 1/2 w resistor. They're rated 1500 mcd, so are still quite bright at 10 mA and the resistors stay cool.

Forgot to mention that the lamps are ground-switched, so I put a single resistor up at the connector board and used just one of the positive wires in a common-anode arrangement.

Last edited by JVRaines; 03-02-2015 at 05:15 PM.

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