JP1 Remotes

The Robman · Posted: Fri Apr 15, 2005 9:30 am Post subject:

I actually ordered this tool a week or so back for the purpose of removing small surface mount components, and I still have a few scappy URC-8910 remotes lying around, so who knows, I might try the mod myself just to see how much the tool helps.

I don't have a supply of surface mount LEDs, but I guess I could try and source some from another remote.
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Nils_Ekberg · Posted: Fri Apr 15, 2005 10:13 am Post subject:

Gee Rob, maybe you can source the LED's from that slightly modded 8910 I sent you. You know, the one the kids had modded Laughing

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The Robman · Posted: Fri Apr 15, 2005 12:30 pm Post subject:

Yeah, but doesn't that remote also have a red backlight? Doesn't make much sense to swap red LEDs for more red LEDs! Smile

Oh yeah, I've been meaning to post some pictures of your modded remotes, just in case anyone else wants to do the same mod! Twisted Evil

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Nils_Ekberg · Posted: Fri Apr 15, 2005 12:52 pm Post subject:

Mark Pierson · Posted: Fri Apr 15, 2005 4:22 pm Post subject:

Tommy Tyler · Posted: Thu Apr 21, 2005 4:19 pm Post subject:

If you guys are really getting into this you should be buying your LEDs from one of the Hong Kong eBay stores. The one I like best is Chi Wing. Their products are top notch, and fast shipping by mail is free. Check out:

http://stores.ebay.com/Chi-Wing-LED-product-shop

The first few pages are high quantity/high price packages, but it gets better as you go, all the way down to packages as small as 10 LED's for $3 including shipping. If you search for surface mount you'll find they have red, orange, blue, and white surface mount LEDs for 7 to 26 cents each, depending on quantity.

And whatever you do, don't pass up a package of 50 super white LEDs, 5mm, 15000mcd, for just $19. You'll never want to use any other LED for an indicator.

Tommy

jherrick · Posted: Fri Apr 22, 2005 7:09 am Post subject:

Just an update.
I tried part numbers 638-19217W1DNPHY3 and 638-19217BHCN1P23 from Mouser. These are 40mcd LEDs. They didn't even produce enough light for me to see them through the rubber keypad. So now I am waiting for a package from Allied with some 150mcd blue LEDs. I also looked more closely at the plastic "waveguide" and it appears that UEIC has someone there with some common sense designing (at least) that part. Where the LEDs go are holes, and instead of making them flat edges that may limit the height of an LED, they have made them beveled and able to accommodate a domed LED. This is significant because the domed LEDs generally put out more mcd than the flat. Unfortunately, I don't believe there is room for a 3mm LED of the sort used in indicators, so we have to stick with surface mount for now.
Another thing I have discovered is that a white surface mount LED is hard to come by, and even harder to find in the high mcd rating that we need. I am sticking with blue just for now, and if this works, I will try green and try to find white.
I should have that package by today, and should be able to continue this weekend (I hope).

jherrick · Posted: Fri Apr 22, 2005 7:19 am Post subject:

The Robman · Posted: Fri Apr 22, 2005 10:10 am Post subject:

I checked the Chi Wing listings and all their surface mount LEDs are 0805, whereas Jim said we need 0603. I found another seller from Hong Kong called tdltdcomhk who has 0603 LEDs listed. You'll want to get them from his listings rather than his ebay store though because the prices are MUCH cheaper. For example, he has a regular listing for 25pcs of super bright LEDs for $8.99 plus $2.50 s/h, whereas the equivilent store listing is $13.49 plus $2.50 s/h. I see that alot of his $8.99 listings go unsold, so don't bid up the price too high on a listing if you see someone else bidding on it, because he probably has another listing which closes later that you can bid on.

To show you how the pricing seems to work, this guy is selling 25 white LEDs for $8.99, 50 blue ones for $8.99 and 100 red ones for just $5.99!

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jherrick · Posted: Fri Apr 22, 2005 10:29 am Post subject:

Wow, those white LEDs look like they would work. I may have to get some from him. They have the right voltage and mcd rating.

Yes, the LEDs currently used by UEIC are 0603, but a 0805 will usually fit on 0603 pads. So if we could find some of those that were quite reasonable, they are also an option. I'm really hoping that my package comes today, as I want to try this.

Have you had a chance to try your thermal tweezers yet? I have a pair here that I will be using to remove the LEDs I currently have on there. For whatever reason, before you mentioned it I had completely forgotten I had them, so used an iron. I dug them out from behind some stuff a couple days ago.

The Robman · Posted: Fri Apr 22, 2005 12:20 pm Post subject:

I haven't done any remote hacking in quite a while, so no, I haven't tried using the tweezers yet. Plus of course, I don't have any different color LEDs to trw swapping them with.
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jherrick · Posted: Fri Apr 22, 2005 1:57 pm Post subject:

Well my package did NOT come today. Man, I ordered them on Tuesday and still not here. Texas to Mass. shouldn't take that long! So now I guess it'll be Monday before I get the chance to try. Mad

jherrick · Posted: Tue Apr 26, 2005 2:43 pm Post subject:

Preliminary results are that the transplant was a success. I have a nice blue backlight, with red display. I will try to get a picture, but there are some issues with what I have done.

First, I ordered the LEDs from Allied last Tuesday and they shipped last Wednesday at 4AM. I just got them in MA today. Ridiculous. But, as Arlo Guthrie says, I told you that to tell you this:
I ordered LEDs without seeing the spec sheet (it wasn't available from the Allied website), and they are spec'ed at 3.5V Vf (forward voltage). It was after I had ordered them that I realized (by looking at Tommy's post) that we needed ~2V. It wasn't until today that I bothered to look up the spec sheet, and saw that they were indeed 3.5V typical. So why is this significant?

The LEDs are in a series parallel circuit, with two LEDs in each parallel branch. The voltage to them is supplied by an op amp on the board. This op amp is not putting out enough voltage to drive more than two ~2V LEDs in each branch. So when I tried two of the 3.5V blue LEDs, they didn't light. Everything else did. Bummer. That's when I looked up the specs. OK, jumpered the pads of one LED, put the blue dome on the other pads: light. Cool! So I put some 0 Ohm 0603 resistors in place of one LED in each branch and soldered on the blue LEDs in the other positions. Works great. Now the LCD panel backlighting. Hmmm.

The LEDs there are right angle LEDs. They look like the LEDs shown here: http://rocky.digikey.com/WebLib/Stanley/FA1101F.pdf (maybe they are?). Not something I want to mess with right now. Red display is OK for now.

Now to put it together.

The waveguide (plastic sheet) has beveled holes, but they aren't deep enough for the dome LEDs that I ordered (next time I would try to find some that are shorter). So I drilled holes the size of the dome in the plastic where necessary, and it fit well. Put it together and it looks pretty good, but because I have a very bright LED on only one side of the board (alternating) it is obvious. I think we need LEDs that are at least 50mcd with ~2V or less forward voltage, and less than 1.5mm tall. 0603, 0805, and even the 3.2 x 2.4mm LED I was using will work if you scrape the board mask off the traces far enough to expose the copper just beyond the LED. Hobby knife or razor blade works good for that.

Images aren't very good, but they are here:

The Robman · Posted: Wed Apr 27, 2005 12:12 pm Post subject:

Just FYI, I was chatting with one of my insider friends about this topic and he expressed a few concerns with the white LEDs:

1.) Forward Voltage Drop is high around 3 Volts.
2.) This will reduce the over all battery life.
3.) For 3 Volts products a voltage doubler is needed.
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jherrick · Posted: Thu Apr 28, 2005 8:41 am Post subject:

I had a chance this morning to take a closer look at the circuit. The op amp does not provide the voltage for the LEDs. They receive their voltage pretty much directly from the batteries. In my configuration, there is about 3.8V dropped across each branch of the LED circuit, and so the 3 volt LEDs wouldn't work in series.

If a voltage doubler was used, the doubled voltage would also find it's way to other components. Some of them are controlled by a 3.6V regulator, which would handle a 12VDC input easily according to it's specs, but there may be other places that wouldn't care much for it, like the LCD controller. I didn't see a regulator on the Vcc to it, and wouldn't want to increase it's Vcc too much.

I have noticed again that most of the blue and white LEDs are about 4-5Vf, so I am not sure that is going to work very well. I have a couple more experiments to do, and try to see if I can figure something out.