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Author Topic: FT-747GX s-meter lamp  (Read 1899 times)
KG5UN
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Posts: 23




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« on: April 01, 2014, 12:44:46 PM »

I have been unable to come up with info on replacing the s-meter lamp in a Yaesu FT-747GX.

Does anyone one have the specs or a source?
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W9GB
Member

Posts: 2616




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« Reply #1 on: April 01, 2014, 04:30:56 PM »

Yaesu FT-747GX Service Manual (Technical Supplement)
http://w5jgv.com/downloads/FT-747%20Technical%20supplement,%20A3.pdf

Page 3 : S-meter is Yaesu part # M0290057

Page 12 : DISPLAY UNIT - PC Board X-Ray and Component layout.
Page 13 : Schematic Diagram of Display Unit.
ALL of these Lamps are 8 Volts, T-1 in size (grain of wheat), and mounted (soldered) to this PC Board.

Page 37 : PARTS LIST for Display Unit
--
Display Backlighting Lamps: PL01 and PL02
S-Meter Lamp: PL03

PL3001, PL3002, PL3003 : Yaesu Part # Q1000010 : Lamp : 8 V, 100 mA : OEM Part # BQ041-22803A
===
Fox Tango Discussion
This SAME Lamp is used on main RF Board as Protection for Front End of Receiver (FD1; F1001)
http://lists.contesting.com/_yaesu/2003-05/msg00025.html

June 2013 discussion (QRZ) on this same topic
http://forums.qrz.com/showthread.php?393577-Sources-for-FT-747GX-Battery-Replacement

WY3A Information for Lamp Replacement
http://www.qsl.net/wy3a/Lamp_Fuse.htm
« Last Edit: April 01, 2014, 04:57:25 PM by W9GB » Logged
KA4POL
Member

Posts: 1966




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« Reply #2 on: April 01, 2014, 09:48:28 PM »

You also might consider exchanging the lamp against an LED with a resistor to keep the current down.
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KG5UN
Member

Posts: 23




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« Reply #3 on: April 02, 2014, 06:23:19 AM »

Thanks for the help. Current draw is not really an issue, just looking for a simple solution.
Perhaps a 3.3 volt led with a dropping resistor would be easy.
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KA4POL
Member

Posts: 1966




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« Reply #4 on: April 02, 2014, 06:39:37 AM »

Main thing is the eternal life of a LED, unless you overpower it  Wink
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KG5UN
Member

Posts: 23




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« Reply #5 on: April 02, 2014, 08:21:36 AM »

I found a mod suggesting a 3.3v led and a 220 ohm 1/2 watt resistor. I think that is the route I will take.
thanks.
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W9GB
Member

Posts: 2616




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« Reply #6 on: April 02, 2014, 04:09:36 PM »

BTW, supplies are PLENTIFUL of this bulb / front-end fuse in UK.
G-WHIP has over 300 of these original Yaesu antenna fuses (FT-757/ FT-102)
 Q1000010 F359A BQ041-2783A, approx 10 ohms in value.

http://www.gwhip.co.uk/radiospares.htm

Geoff does have his store closed the next 3 weeks for Spring/Easter vacation.
G-WHIP - Southampton, UK acquired these from former Yaesu UK/EU parts warehouse.
« Last Edit: April 02, 2014, 04:25:11 PM by W9GB » Logged
N4NYY
Member

Posts: 4747




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« Reply #7 on: April 03, 2014, 04:39:48 AM »

I found a mod suggesting a 3.3v led and a 220 ohm 1/2 watt resistor. I think that is the route I will take.
thanks.

If that is a 12V (13.Cool, I would use a 470 or 560, just to be safe. Nothing will happen other than burning out your LED. But at least you do not have to rip it apart. You would have to measure the supply voltage and then use online calculators.

BTW, I do these mods all the time. Use a flat LED. They are 180 degree dispersal of light. Rounded LED give you a spot effect. Also, there are some kooks that will tell you to sand a rounded LED down flat. That is one of the dumbest things and biggest wastes of time you can do. Flat LEDs are dirt cheap.
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W9GB
Member

Posts: 2616




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« Reply #8 on: April 03, 2014, 11:58:13 AM »

Quote
If that is a 12V supply ...
NO, Yaesu uses an + 8 Volt rail for the 3 lamps (bulbs) on front panel,
as noted in my earlier answer (April 1, BUT not a "punked" answer.)

Incandescent Lamp is 8 Volts, 100 mA.

PL3001, PL3002, PL3003 : Yaesu Part # Q1000010
Lamp : 8 V, 100 mA : OEM (East Asia) Part # BQ041-22803A
« Last Edit: April 03, 2014, 12:00:48 PM by W9GB » Logged
N4NYY
Member

Posts: 4747




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« Reply #9 on: April 03, 2014, 05:12:57 PM »

Quote
If that is a 12V supply ...
NO, Yaesu uses an + 8 Volt rail for the 3 lamps (bulbs) on front panel,
as noted in my earlier answer (April 1, BUT not a "punked" answer.)

Incandescent Lamp is 8 Volts, 100 mA.

PL3001, PL3002, PL3003 : Yaesu Part # Q1000010
Lamp : 8 V, 100 mA : OEM (East Asia) Part # BQ041-22803A

OK. Good info. So the online calulator would be useful with that supply voltage. That 220 may be OK.
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