Infrared LED vs visible ones

Forums › Home Workshop DIY › Infrared LED vs visible ones

DarthKermit

5346 posts

Uber Geek

Trusted

#255606 20-Aug-2019 16:35

Friend of mine has given me his TV remote to try and fix. It's dead. No signal coming from the LED.

I was wondering if I replaced the infrared LED with a normal LED (visible light to us), whether his TV would "see" it?

SATTV

1648 posts

Uber Geek

ID Verified

#2302439 20-Aug-2019 16:58

Some Red LED's can be used however the price of an infrared LED is not that much more expensive.

How do you know the LED is the problem?

You can check the LED by using the camera on your phone, you will see the LED pulsing.

Clean the pads, I used to use isopropal alcohol but you could use vodka ( meths can leave a residue ), spit also works.

Also check the 455KHz oscillator or crystal and make sure the legs have not broken, this was a common fault 30 years ago when I was doing my apprenticeship.

Ughhhhhh - I am old, I can say 30 years ago :-(

I know enough to be dangerous

DarthKermit

5346 posts

Uber Geek

Trusted

#2302554 20-Aug-2019 18:18

SATTV:

Some Red LED's can be used however the price of an infrared LED is not that much more expensive.

How do you know the LED is the problem?

You can check the LED by using the camera on your phone, you will see the LED pulsing.

Clean the pads, I used to use isopropal alcohol but you could use vodka ( meths can leave a residue ), spit also works.

Also check the 455KHz oscillator or crystal and make sure the legs have not broken, this was a common fault 30 years ago when I was doing my apprenticeship.

Ughhhhhh - I am old, I can say 30 years ago :-(

I have some small red LEDs at home. I don't have any infrared ones. So I thought about replacing the existing one with one I already have.

I've viewed the remote using a camera and no light is emitting from the LED.

I'm trying to work thru what the problem could be. Batteries is not the issue. The battery terminals all appear ok. There's nothing obvious as to why it has failed.

timmmay

20589 posts

Uber Geek

Trusted

Lifetime subscriber

#2302574 20-Aug-2019 19:34

Not worth the bother to fix unless you enjoy it. Just buy one of these from Amazon, they work well. Much simpler than the Harmony I had before, more robust, better battery life, works well.

k1w1k1d

1527 posts

Uber Geek

#2302581 20-Aug-2019 19:50

Just a note if you are using an iPhone to check LED remotes.

From the i4(?) onwards there is an IR filter on the main camera, so you won't see any flashes. Use the front/selfie camera as it doesn't have the IR filter.

elpenguino

3427 posts

Uber Geek

#2302585 20-Aug-2019 19:57

DarthKermit:

SATTV:

Some Red LED's can be used however the price of an infrared LED is not that much more expensive.

How do you know the LED is the problem?

You can check the LED by using the camera on your phone, you will see the LED pulsing.

Clean the pads, I used to use isopropal alcohol but you could use vodka ( meths can leave a residue ), spit also works.

Also check the 455KHz oscillator or crystal and make sure the legs have not broken, this was a common fault 30 years ago when I was doing my apprenticeship.

Ughhhhhh - I am old, I can say 30 years ago :-(

I have some small red LEDs at home. I don't have any infrared ones. So I thought about replacing the existing one with one I already have.

I've viewed the remote using a camera and no light is emitting from the LED.

I'm trying to work thru what the problem could be. Batteries is not the issue. The battery terminals all appear ok. There's nothing obvious as to why it has failed.

If the red LED does work at all you'll get reduced range. There's usually optical filtering on the receiver and with a visible red LED you won't emit enough IR light for the receiver to lock on to the signal.

By all means use a visible LED for diagnosis and then refit the IR.

I've never seen an IR LED fail but you can check it with a multimeter. As you've been told the cause is more likely a dirty key pad or oscillator. Or mebbe even cracks in the PCB if the remote's been treated roughly.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

SATTV

1648 posts

Uber Geek

ID Verified

#2302596 20-Aug-2019 20:30

k1w1k1d:

Just a note if you are using an iPhone to check LED remotes.

From the i4(?) onwards there is an IR filter on the main camera, so you won't see any flashes. Use the front/selfie camera as it doesn't have the IR filter.

Thanks for the heads up, this was my go to.

It worked on my iPhone 5, I just checked on my iPhone 6s, still works but not as bright.

John

I know enough to be dangerous