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#1
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Icom IC-28H Backlight Replacement
My Icom IC-28H has gone dark. Looks like both lamps are gone. The
schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#2
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Try Radio Shack, as they had some grain of wheat bulbs at various voltages.
Bob N9LVU Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#3
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My problem is I had to disassemble the radio so far to get to the back
of the lamps, I can't run it to check the voltage. The lamps are driven by an automatic dimmer circuit, so can't just trace the source. Would like to see a data sheet on the lamps, but doesn't seem to be available. I saw one reference to Intersil as the manufacturer, but it's not listed on their website. Dick On Fri, 18 Mar 2005 13:59:07 -0600, Robert Kubichek wrote: Try Radio Shack, as they had some grain of wheat bulbs at various voltages. Bob N9LVU Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#4
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If you look at the schematic, you will see that there is 11.5v supplied
to the lamps for the display, ANY grain of wheat lamp rated for 12-15v will work. Radio shack does sell them, most older Icoms IC229H ect use them. Bob N9LVU Dick wrote: My problem is I had to disassemble the radio so far to get to the back of the lamps, I can't run it to check the voltage. The lamps are driven by an automatic dimmer circuit, so can't just trace the source. Would like to see a data sheet on the lamps, but doesn't seem to be available. I saw one reference to Intersil as the manufacturer, but it's not listed on their website. Dick On Fri, 18 Mar 2005 13:59:07 -0600, Robert Kubichek wrote: Try Radio Shack, as they had some grain of wheat bulbs at various voltages. Bob N9LVU Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#5
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I sure don't see that Bob. The lamps are driven off the collector of
Q12. This voltage varies in accordance with the light received by R3. I don't see any reference to voltages at all anywhere in that circuit.. Dick On Fri, 18 Mar 2005 15:53:06 -0600, Robert Kubichek wrote: If you look at the schematic, you will see that there is 11.5v supplied to the lamps for the display, ANY grain of wheat lamp rated for 12-15v will work. Radio shack does sell them, most older Icoms IC229H ect use them. Bob N9LVU Dick wrote: My problem is I had to disassemble the radio so far to get to the back of the lamps, I can't run it to check the voltage. The lamps are driven by an automatic dimmer circuit, so can't just trace the source. Would like to see a data sheet on the lamps, but doesn't seem to be available. I saw one reference to Intersil as the manufacturer, but it's not listed on their website. Dick On Fri, 18 Mar 2005 13:59:07 -0600, Robert Kubichek wrote: Try Radio Shack, as they had some grain of wheat bulbs at various voltages. Bob N9LVU Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#6
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In the sevice manual, the junction of R77-R78-Q12 is 11.5v and this goes
out to the lamps. Bob N9LVU Dick wrote: I sure don't see that Bob. The lamps are driven off the collector of Q12. This voltage varies in accordance with the light received by R3. I don't see any reference to voltages at all anywhere in that circuit.. Dick On Fri, 18 Mar 2005 15:53:06 -0600, Robert Kubichek wrote: If you look at the schematic, you will see that there is 11.5v supplied to the lamps for the display, ANY grain of wheat lamp rated for 12-15v will work. Radio shack does sell them, most older Icoms IC229H ect use them. Bob N9LVU Dick wrote: My problem is I had to disassemble the radio so far to get to the back of the lamps, I can't run it to check the voltage. The lamps are driven by an automatic dimmer circuit, so can't just trace the source. Would like to see a data sheet on the lamps, but doesn't seem to be available. I saw one reference to Intersil as the manufacturer, but it's not listed on their website. Dick On Fri, 18 Mar 2005 13:59:07 -0600, Robert Kubichek wrote: Try Radio Shack, as they had some grain of wheat bulbs at various voltages. Bob N9LVU Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#7
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Try part number 606-CM7219 from mouser.com, $0.35 each.
Ron - K0QVF Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#8
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Thanks. I had found that lamp in the Mouser catalog. However, the
last time I applied power to the IC-28H, one of the lamps came back to life. When I observe it from the backside of the circuit board, the lamp has a definite green glow. I assume this is what gives the green look to the display. I read a message from one person who used amber LED's to give it an amber display. This leads me to conclude that the color of the lamp light is what determines the color of the display. I have not seen any 7219 lamps on the Internet that are green. Still looking. Dick On Thu, 31 Mar 2005 16:50:51 -0600, Ron wrote: Try part number 606-CM7219 from mouser.com, $0.35 each. Ron - K0QVF Dick wrote: My Icom IC-28H has gone dark. Looks like both lamps are gone. The schematic lists these lamps as HRS-7219A-G40. I found a couple of places that had minimum orders of $100 and $300 respectively. That's out. I read a message on eham.net where a ham had replaced these lamps with amber LED's and appropriate resistors. Anyone done this? Other options? Dick - W6CCD |
#9
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In article ,
Dick LeadWinger wrote: Thanks. I had found that lamp in the Mouser catalog. However, the last time I applied power to the IC-28H, one of the lamps came back to life. When I observe it from the backside of the circuit board, the lamp has a definite green glow. I assume this is what gives the green look to the display. I read a message from one person who used amber LED's to give it an amber display. This leads me to conclude that the color of the lamp light is what determines the color of the display. I have not seen any 7219 lamps on the Internet that are green. Still looking. How about using a standard bulb (as in the Mouser catalog) and giving it a light coat of green nail polish? A light-green LED with series dropping resistor might also give you the desired hue. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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