Need to replace a "wheat" light in a piece of audiophile gear- Here's a pic of bulb- What do I need?

[astro]

I acquired this NAD 5425 CD player in absolutely perfect, cherry shape the other day. It works flawlessly except the light bulb that illuminates/back lights the segmented display is burned out. In googling this is apparently a common issue for this unit.

I used a high intensity flashlight as a substitute back light to confirm the display module is working properly I would prefer to fix this before trying to sell it online. Beyond the fine wires leading to the PC board my main concern is the value of the lamp. My multi-meter is in another location at this point, but even if I had all I could determine was the voltage, I wouldn’t be able to tell the wattage spec of the lamp. Is there any way to tell by the pic?

Pic 1 - Top
Pic 2 - Bottom
Pic 3 - Whole board

[astro]

I found this on another website but I don’t see a resistor in series on this lamp. It’s just soldered right to the board.

Hi Rob M,

Display is LCD with backlight, no VFD. On 5425 shematic lamp is connected between -15V and 0V with 10R 0.5W resistor in series.

Josip

So what does this mean re what I need to ask for? Beyond this where to get one? I’m pretty sure Radio Shack does not carry these.

[KneadToKnow]

Can’t help with identification, but once you know what you’re after, try Parts Express

[beowulff]

I’d just replace it with an LED and the correct value resistor.

[astro]

@beowulff

I’d just replace it with an LED and the correct value resistor.

This guy said that might be diceysince they have different illumination characteristics.

Hi Rob,
Even LCD displays are scanned. The waveform has an average zero, that’s all.

You may be able to use those night lights. I’ve been thinking of ways to use them as you can get 3 for $4 ~ $5. Nifty green colour on some of them. Pressure contact fit for 120 VAC.

You can use white LED’s but the emission angle can’t compare to a light bulb. You may have to space them back. If it’s edge lighting - you’re in business. Run them with a current source. Cheap and cheerful.

[beowulff]

@astro

This guy said that might be diceysince they have different illumination characteristics.

I’m sure that’s true, but if you can’t find a replacement bulb, it’s probably the best solution. That, and I have tens of thousands (literally) of LEDs in my parts bins…

I’ve done this sort of thing before, and one of my solutions to the narrower angle of the LED is to use a Dremel to flatten and roughen the lens of the LED.

[Batfish]

Would this help?

http://cgi.ebay.com/NAD-5420-5425-Service-Manual_W0QQitemZ380191129922QQcmdZViewItemQQimsxZ20091224?IMSfp=TL091224218004r22670

[astro]

@beowulff

I’m sure that’s true, but if you can’t find a replacement bulb, it’s probably the best solution. That, and I have tens of thousands (literally) of LEDs in my parts bins…

I’ve done this sort of thing before, and one of my solutions to the narrower angle of the LED is to use a Dremel to flatten and roughen the lens of the LED.

So are there 12 -16 volt super bright LED assemblies out there or is this a roll your own deal by using a resistor? I ask because the leads on this wheat lamp are very, very thin and my soldering iron is a generic, cheap 25 watt Radio Shack model. I don’t want to nuke the board.

[astro]

@Batfish

Would this help?

http://cgi.ebay.com/NAD-5420-5425-Service-Manual_W0QQitemZ380191129922QQcmdZViewItemQQimsxZ20091224?IMSfp=TL091224218004r22670

I didn’t use the ebay sale but it did spur me to search again for one on the web and I found one free via a manual exchange service. Now I need to upload one to pay them back.

It’s a 15 volt 60 milliamp lamp.

Thanks to everyone for their input!

[beowulff]

@astro

So are there 12 -16 volt super bright LED assemblies out there or is this a roll your own deal by using a resistor? I ask because the leads on this wheat lamp are very, very thin and my soldering iron is a generic, cheap 25 watt Radio Shack model. I don’t want to nuke the board.

Search for LEDs with integrated resistors for use in Automobile accent lighting - they’re all over ebay. Be careful - many of these may be too big for the space available.

If you want to cobble this together yourself, I think your 25w iron should be fine - just make the LED/resistor assembly and solder on some small, stranded wire, tin it, and then poke the wire into the holes in the PCB where the old lamp leads were. This is a single-sided PCB, so keep the iron on the pad for as short a time as possible. I clean the tip of my iron, and then in one motion, melt a little solder onto the tip, and transfer that to the pad - the residual solder on the pad will melt, along with the solder on the leads and the solder on the tip, and will make a nice joint, without overheating anything.

[astro]

@beowulff

Search for LEDs with integrated resistors for use in Automobile accent lighting - they’re all over ebay. Be careful - many of these may be too big for the space available.

If you want to cobble this together yourself, I think your 25w iron should be fine - just make the LED/resistor assembly and solder on some small, stranded wire, tin it, and then poke the wire into the holes in the PCB where the old lamp leads were. This is a single-sided PCB, so keep the iron on the pad for as short a time as possible. I clean the tip of my iron, and then in one motion, melt a little solder onto the tip, and transfer that to the pad - the residual solder on the pad will melt, along with the solder on the leads and the solder on the tip, and will make a nice joint, without overheating anything.

It may be worthwhile to try that. These lamps seems pretty prone to burnout. I wonder if they are being over driven or overheated by being enclosed in that little white hood I removed.

[beowulff]

@astro

It may be worthwhile to try that. These lamps seems pretty prone to burnout. I wonder if they are being over driven or overheated by being enclosed in that little white hood I removed.

Could be all of the above.

But, all bet their rated lifetime isn’t great - probably a few thousand hours, which goes by pretty quickly if you leave the unit on most of the day.

[astro]

@beowulff

Could be all of the above.

But, all bet their rated lifetime isn’t great - probably a few thousand hours, which goes by pretty quickly if you leave the unit on most of the day.

Odd then, that that would be the choice for a supposedly premium piece of audio gear. They should have made it with clips for replacement. It’s soldered in there as permanent piece of the equipment.

[beowulff]

@astro

Odd then, that that would be the choice for a supposedly premium piece of audio gear. They should have made it with clips for replacement. It’s soldered in there as permanent piece of the equipment.

Just like the inaccessible dashboard lights in my truck - soon I’ll need night vision goggles to see the speedometer…

[astro]

@beowulff

Just like the inaccessible dashboard lights in my truck - soon I’ll need night vision goggles to see the speedometer…

Cheap GPS units make great replacement speedometers in addition to their other functionality.

[astro]

It looks like these should work. They don’t look as big as the light on the MB however.