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There are two kinds of problems with remotes:
1. They seem to have legs of their own and disappear at the most inconvenient times.
2. They get abused by being dropped, dunked in Coke or beer, chewed on by the pet tiger, or left alone to develop dead leaky batteries.
While there are some remotes that will respond to a whistle and beep back to identify their location, most are the ordinary deaf, dumb, and blind variety. I cannot help you locate your missing remotes. If you have disappearing remote syndrome, a well designed universal remote - on a tether - may make a good investment. However, the following was too good to pass up:
(From: Bill Samuel (phantom@isoc.net).)
"In '89, a Customer brings in their VCR for me to fix. (Zenith VRE-200) It won't accept tapes, plus their kids misplaced their remote, so they wanted a price on a new one.
Well, after taking the unit apart, I called them and said, "Sir, I've found the problem with your VCR. BTW, you don't need a new remote.""
Most actual problems with remotes can be solved relatively easily. They are often of a physical nature. Since remotes operate on low voltages under non-stressful conditions, spontaneous electronic failure is relatively uncommon. The following are not good for remotes: Sitting or stepping on them, using them as drink stirrers, door stops, projectiles for target practice, substitutes for dog bones, or depositories for your old leaky batteries.
However, if you go inside the TV, VCR, or other controlled device, see the respective repair guide for that equipment for essential SAFETY information.
To narrow down the problem, use an IR detector to determine if the remote is emitting an IR signal when each button is pressed. While this does not guarantee that the signal is correct, it eliminates most common problems from consideration. An IR detector card or an IR detector circuit like one of those described in the section: IR Detector and Related Circuits are very handy for testing remote controls and other IR emitters. Some camcorders, video cameras, and digital cameras (those that do not incorporate an IR-blocking filter) are sensitive to IR as well and will show a bright spot of light if aimed at a working source of IR. However, since there might be an IR-blocking filter, a negative response is not definitive unless you confirm that the camera responds to a known working remote. And, PCs and PDAs with IR links and suitable software (e.g., OmniRemote for the Palm III) may be useful for remote testing. See the section: Some Alternative 'Quick and Dirty' Remote Testers for additional options.
MCM Electronics, Centerville, Ohio/1-800-543-4330, list 2 different shaped cards for $7.29 each (#72-005/3.5 x 2.5" card & 72-003 /4.75 x 0.75" probe. Radio Shack, Edmund Scientific, and others offer similar detectors.
The salvaged IR sensor module from a TV or VCR may also be used as an IR detector. These usually operate from a single supply (12 V typical) and output a clean demodulated signal - you will not see the carrier, only the 1s and 0s. This will be true of an IR detector circuit as well unless you are careful to position the remote and photodiode just so as the circuit acts as somewhat of a low pass filter due to the B-E capacitance of the transistor. Radio Shack and Digikey (among other) also sell inexpensive IR receiver modules (under $5) which would also provide a demodulated signal for your viewing pleasure. However, note that some may be tuned for a particular carrier frequency like 40 kHz and therefore may not respond to all remotes. (Note, I have heard of spurious pickup issues with some of the Radio Shack units - they are not the same as those sold a while ago.)
(From: Brett Walach (bwalach@dpg.devry.edu).)
For anyone needing a great IR receiver at a reasonable price, try Radio Shack's MOD1. It's an IR receiver that demodulates the data for 40Khz x-mitters. The output can then be viewed on a scope or used to drive a small transistor which would in turn drive a speaker! The output from the MOD1 is the inverse of the code sent. That is, the TTL logic level from the MOD1 is high when no IR is present. If by chance you need an IR receiver that operates on a different carrier, try DigiKey (1-800-DIGI-KEY). I know that they have the other two types for sure.
CAUTION: You can easily turn a simple repair (e.g., bad solder connections) into an expensive mess if you use inappropriate soldering equipment and/or lack the soldering skills to go along with it. If in doubt, find someone else to do the soldering or at least practice, practice, practice, soldering and desoldering on a junk circuit board first! See the document: "Troubleshooting and Repair of Consumer Electronic Equipment" for additional info on soldering and rework techniques.
Test equipment beyond a good eye and maybe a multimeter is rarely needed.
The most challenging part of repairing a remote hand unit may be just getting inside! Manufacturers seem to pride themselves on the extent to which this is becoming more nearly impossible without dynamite:
The following are the most common types of problems and suggested solutions. As noted, most are physical in nature: dead batteries, gunk, bad connections.
For all but the first two, disassembly will be required. Manufacturers seem to be using more and more creative (read: obscure and difficult to open) methods of fastening the two halves of the remote shell together. There may be a screw or two and/or the case may simply 'crack' in half by gently prying with a knife or small screwdriver along the seam or sliding the two halves a fraction of an inch to unlock some catches. Look for screws on the back (possibly under a not-so-easy to peel off label) and inside the battery compartment, as well as hidden snap fasteners.
Make sure that all the batteries point in the correct direction as marked inside the battery compartment or under its cover. If it uses more than 2 batteries, getting one in backwards could also result in weak or erratic operation.
In addition, check selector, power, or enable) switches for proper operation. Remove the batteries and use an ohmmeter to test across the contacts with the switch(es) in all positions. These switches can be easily damaged as a result of dropping or squashing the remote. The contacts may become dirty, gunked up, corrode, or simply wear out as well. Locating a replacement may prove challenging. Disassembling the switch may allow you to clean or restore the contacts in some cases.
The frequency is often 455 kHz (I assume since they are widely used as filters in the IF section of AM radios and are thus inexpensive.)
If you have an oscilloscope, check for signals on the IC when buttons are pressed - if there is no action on any pin, then you may have a bad resonator (or bad IC, etc.). Monitoring on one lead of the ceramic resonator should produce a signal at its resonant frequency when a button is pressed. A typical waveform may have an amplitude of a few tenths of a volt.
If you do not have a scope, one possible indication of a bad resonator (aside from it being smashed) would be a steady output from the IR LED for all button presses - normally the output would be visibly pulsating. Of course, this could indicate a bad IC as well.
A ceramic resonator usually is a small blue or orange object that looks similar to a plastic (sharp edges) or dipped (smooth edges) capacitor.
The circuit board marking will be X1 or CR1 or something like that. Replacements may be available from places like MCM Electronics or other electronics distributors. Or, consider an organ donation from a remote for equipment that has long since gone to that entertainment center in the sky if the frequency of its resonator is the same.
However, the frequency may be fairly critical for proper operation (within 5 percent or better may be required for some) and while not a common failure, I've heard of the resonator frequency changing (probably from a trauma) by enough to cause problems.
(From: Lewin A.R.W. Edwards (sysadm@zws.com).)
If your resonator has 3 pins instead of 2, and you can't find a replacement, you can use a 2-pin resonator, but you'll need to add two small caps (perhaps 33 pF?) between the legs of your resonator and ground.
Once you think you got it all, do it again - and with soap and water as well - both the rubber and circuit board.
This goo may originate from a number of sources (no one seems to know for sure) including: body oils, spills, plasticizers from the flexible keypad, protective grease, etc. Unless you had dunked the remote in a vat of motor oil to create this problem there may be no sure way to prevent it from returning in the future. More below.
I have one (1) data point to suggest that cleaning the rubber pad with a soft pencil eraser may be better than washing. However, this may also remove the conductive material in some units.
(From: Steve Lenaghan (tamerica@prairie.ca).)
We do a ton of cordless phones and I have never had to repair a conductive pad in my career (35 years). We soak them in scalding water and dish soap for 30 minutes. I clean the PC boards with alcohol and a rough cloth. Works every time.
(From: Michael Shell (mikes1987@yahoo.com).)
People have noticed that the keys (and remotes) that are used more often, tend to have more oil problems. This is in agreement with my observations.
One thing I have to make clear is that I *KNOW* that whatever is going on is NOT due to spillage or other external contamination. If I had not seen it with my own eyes, I would not believe it either! Sometimes the keys that are used most often (and have the most oil) are in the center - this is a LONG way for an external contaminant to have to travel!
The oil behaves a bit differently from most normal household (and hand) oils.
I would not have noticed these fine points except for the fact that I have worked with Silicone (DOT 5) brake fluid which, except for an added purple dye, behaves in the same way.
Check this out: Silicone Rubber Components Manual (down at the bottom, section 7.0, Quality).
So, it seems the silicone keypad manufacturers have been keeping a dirty little secret all these years!
I guess we all have to look forward to our 3 year cleaning ritual. I suppose a hardcore hardware hacker could do his own keypad baking and post some before and after weight measurements to tell us how many grams of oil these things hold! (WARNING: you may have to do the baking in an oxygen free atmosphere!)
If the plating has worn off and cleaning the contacts doesn't last for more than a few days or weeks, tinning them with a thin coating of solder should help.
MCM Electronics at 1-800-543-4330 lists a Rubber Keypad Repair Kit for $24.95. It is supposed to contain enough material to repair 400 contacts (2 containers each good for 200 contacts). Their part number is 20-2070. Not cheap but 400 contacts covers quite a few typical remotes. Note: I do not know whether it is easy to mix only enough material for just 1 or 2 contacts - it would be worth confirming that this is possible before ordering. Or else, invite a few dozen friends (and their flakey keypads) over for a remote repair party. :-)
For a similar price, Remote Control Keypad Repair also has a kit for coating the worn out rubber. It consists of a little bottle of some conductive paint which doesn't appear to need mixing.
There is also a material called 'resistive coating' or something like that that goes on like paint. It may be available from an electronics distributor. Or, if you are friendly with your local repair shop, they may be willing to spare a few drops.
Occasionally, the conductive material is not actually worn off entirely only on the surface and there may still be some beneath surface. Light sanding may help.
Unfortunately, there is no single best solution since the material used for the conductive rubber pads in remotes is not all the same.
(From: Paul Weber (webpa@aol.com).)
"If you're looking for aluminum or copper foil tape with adhesive on it, visit your local hardware store, in the plumbing and/or roof rain gutter sections. Alternatively, try an auto parts store. I've found a variety of adhesive foils (including stainless steel) in these kinds of establishments.As for as repairing conductive rubber keypads: I've not used the metal tape method, but will probably try it. I've had great success with a thorough cleaning and light buffing of the contact area with very find (1000 grit) wet/dry sandpaper."
(From: Rufus (Pink@Floyd.Edu).)
"If you can find similar pads on another remote's membrane, trim them off square and use them to replace the defective pads. You can use silicone glue to attach them. Be careful to trim off the same amount from each pad so the buttons throw will be the same, and don't trim too deep as to damage the rubber dome."
(From: Wes Hilterbrand (replayelectronics@usa.net).)
"About the best way I have found is to take an old remote (trash or have absolutely no need for) with the same type of conductive pads. Look for a little used pad (such as a record button), add some skillful maneuvering with an exacto knife, and some SuperGlue, and you can sometimes replace the bad pad(s) on your remote with better pads. The way I have done this is to cut the pad about halfway down from the sheet it's connected to (around the pad's circumference, a little ways under the conductive surface). This should probably be done only as a last resort, and WATCH YOUR FINGERS!BTW, this is just my opinion. I CANNOT be held responsible for any damage incurred due to following this procedure. Try this AT YOUR OWN RISK! Remember, if you mess up your working remote, there is no recourse."
(From: Keith Craig (kcraig@mlode.com).)
"I use a can of 'TV TUBE COAT' (GC Electronics), a conductive paint used for picture-tube aquadag (black paint on outside of picture tube used for ground). Squirt a tiny amount on a piece of paper and use a Q-tip (cotton swab) to drop on the pad."
(From: Mark Saterfield (kc4tzn@webtv.net).)
"Pens are available that come preloaded with conductive ink at local electronics stores though apparently not Radio Shack."
(From: Mike Harrison (wwl@netcomuk.co.uk).)
"It isn't the same as the silver stuff used for car screen heaters, etc., which I'd guess probably dries too hard and cracks off. It's made by Circuit Works, who also do conductive epoxies. Their part number is CW2610 for a repair kit, UK supplier is Farnell, price is UKP 22.33."
(From Rodney A Schmidt (rschmidt@iastate.edu).)
"What I used to remedy it was to use the stainless steel tape that is sold to seal ducting insulation, use a paper hole punch, and super glue the punched stainless onto the pad. I have had extremely good luck using this, and since the stainless is adhesive anyway, it stays in place while the super glue is drying."
Note that strictly speaking, these IR emitters should perhaps be called Infra Red Emitting Diodes or IREDs since they produce no visible light. However, we will use the term IR LED throughout this document since its meaning is understood by the vast majority of readers.
(From: Duane P Mantick).
"An awful lot of IR remotes use IC's from the same or similar series. A common series comes from NEC and is the uPD1986C which, incidentally is called out in the NTE replacements book as an NTE1758. A lot of these chips are cheap and not too difficult to find, and are made in easy-to-work-with 14 or 16 pin DIP packages. Unless you have no soldering or desoldering skills, replacement isn't difficult."
However, some of the One-For-All (and probably others as well) remotes do have capabilities not listed on the package (or web site). Check with the manufacturer (in the case of Universal, this can be via email) to determine whether any of their products have what is needed for your model(s).
Universal 'learning' remotes are available at slightly higher cost (perhaps, $25-100). The better ones are capable of memorizing all of the actual signals sent by your original remotes by viewing the IR transmission directly. Of course, your existing remotes must be working properly for teaching purposes. Make sure you get a money back guarantee with these as some may not be compatible with all equipment. The advantage of a learning remote is that it can be taught to perform setup, adjustment, and programming functions as well as those for normal operation. However the teaching process is likely to be tedious and time consuming and you will have to keep track of which buttons do what - possibly not worth the effort in the end. If the backup batteries should ever go dead, the entire learning process will need to be repeated.
(From: Michael Schuster (schuster@panix.com).)
"You can get most of the Zenith OEM remotes from MCM Electronics. These include some that were sold under the Gemini name as consumer items; their 4-device learning/preprogrammed remote was particularly nice).These definitely =behave= as though they have EEPROMS; i.e. learned functions are retained indefinitely without power.
Also the upgradable one-for-all remotes from Universal Electronics (i.e. the ones with the 'magic' key) almost certainly have EEPROM since they can be customized by moving buttons around and assigning straight binary functions to keys not in the original pre programmed arrangement. Such customizations are also retained if power is lost."
(From: Dakuhajda (dakuhajda@aol.com).)
"Unfortunately RCA remotes cannot be repaired on any made after 1986. The circuit board is molded to the plastic case, only way to get the darn thing apart and you break it beyond being able to put it back together. Rca sells a universal remote control system link 5 that even has the pip feature. Usually $25. If you really want an exact match look inside the battery cover you can get the part number for the remote control, six digits, usually 221000 or similar. You can call any RCA authorized servicer and they can order it for you, or you can contact MCM electronics, Excel electronics, or any other authorized Thomson parts distributor. "By the way the most expensive RCA universal remote that Wal-Mart sells I use in our shop for almost all but the very newest RCA TV sets. Last 2 years models.
(From: techman@niobiumfive.co.uk.)
Some universal remotes are better than others. I recently bought (here in the UK) one called "Wizard" made by Philex (a big manufacturer of replacement remotes). It has several levels of programming:
All this can be setup for 8 different devices. Settings are saved in FLASH memory so you don't lose any programming when the batteries die. :-) It does has a few undocumented quirks, like setting a new manufacturer code seems to clear all existing "learned" codes. :-(
I bought it from Grandata (UK 0208-900-2329, international +44-208-900-2329) for GBP 16.50 + tax and postage.
I have also wired a phototransistor and an IR LED to the serial port on an old laptop, and experimented with turning that into a learning remote. I must say I was surprised at how many different coding schemes seem to be in use, just running through a) above and observing the waveforms I documented about 20 variations before I got bored. I got it working with my UK satellite "digibox" and with a JVC VCR, but haven't taken it much further. I was particularly interested that the VCR (HR-S4700EK) responds to two quite different coding schemes, presumably it was designed to be backward-compatible with some old code of theirs, but the newer code is required to get all the functions to work. A few codes do functions for which there is no button on the official remote (and are normally only accessible from buttons on the front panel!) One code wipes out all ones timer recording settings! :-(
Panasonic has a web site you can enter your model number and get a parts list with list prices and part descriptions:
This site includes support for Panasonic, Technics, and Quasar consumer electronics. However, my quick visit only showed accessory type items (e.g., replacement original remote controls, cables, etc.). Encrypted credit card protection presumably makes it possible to order parts directly.
They also do will research on hard to find remotes.
Test by removing the front panel if possible and direct the remote at the sensor directly. Inspect and clean the sensor window thoroughly with mild detergent and water.
Borrow a replacement or universal remote to determine if the device responds with a known good unit. Check demodulated waveforms with an oscilloscope to confirm proper signal levels and reliable operation. See the section: Diagnosing the Problem as well.
And, there could be a design or manufacturing problem with your set....
While the IR-receiver module inside that TV may be a mature component and may function well on the test bench, it is entirely possible that the TV manufacturer has made a (design) fault in applying it. An IR-receiver is a very sensitive device, and a television is a very dirty environment. This may be a case of an EMC problem, not an optical problem. Under the right conditions, with this type of IR-transmitters and IR-receivers, distances of 100 feet or better may be crossed...
But, this should not be the customer's problem. The service organization of the TV manufacturer is the proper place to obtain a fix. The complaint is valid and it should be cured.
These are likely possibilities if you have just changed your room layout or added something to it:
A neighborhood kid (or adult with the maturity of a kid) may be playing tricks on you from outside your window or even across the street. It doesn't take much (a lens) to extend the effective distance over which a universal remote will operate reliably.
Cover the sensor of the misbehaving equipment with a piece of black tape to see if the problem goes away. Then round up your other remotes (and/or other animate objects) and discipline them!
Turn off all fluorescent lamps to see if the problem goes away. A cardboard baffle can be taped to the sensor to block the interfering light. Try a different brand of compact fluorescent as not all cause interference.
Turn off the lamps or move the Sun
Turn off suspect devices. If the problem goes away, they will need to be
moved to another location. Shielding is probably not a viable option.
There are three ways to solve this problem: changing the wavelength of the light, the modulation frequency, or coding used by the remote. Only the first of these is likely to be realistically possible without major effort and would involve replacing the IR LED(s) in the hand unit with visible ones (red, yellow, or green) and replacing the IR passing filter on the controlled equipment with one selective for the visible wavelength. The silicon sensor in the remote receiver probably will work just fine for visible light. A colored piece of cellophane or plastic may be adequate for the filter. Using a green LED may be best since its wavelength is furthest away from the IR wavelength making the filtering easier.
I have not actually tried this stunt but there is no fundamental reason why it shouldn't work. However, some experimentation may be required to find a suitable high brightness LED and to match it to driver in the hand unit since the LED's voltage drop will be different and may require changing a resistor. And yes, with care, it should be possible to extend this approach to 3, maybe even 4 devices. Multicolored remotes might be kind of cool. :)
The manufacturer of the remote control is the next likely source (after the instruction manual) for the codes and other information. However, there is a good chance that one of the following web sites may be able to help you:
But they suggest using the technical support line (800-636-8352) for remote control programming and other Memorex consumer electronics questions.
In particular, there is information on many many universal remotes including setup instructions. Since, it is likely that your model is actually one of these rebranded by Radio Shack, it is worth checking.
There is complete info on programming and special functions for many models. Since other universal remotes may be rebranded One-For-Alls, this information may be useful for those as well.
There are complete specifications and setup instructions for most of their products (with the rest coming soon).
And here is another one:
Next time, make copies of the instruction manual(s) and put them in obvious places like taped to the back of the TV or inside the entertainment cabinet.
Better yet, print the specific instructions and/or codes on a slip of paper and stuff it into the battery compartment of the remote. Or tape the info to the back and then cover with clear tape to protect it from wear.
One of the primary axioms of life is that you will lose those instruction manuals. :-)
I know this procedure works for models 3 and 4+ and assume it to be similar for the others.
(From: Larry Sabo (sabo@storm.ca).)
"I find it works better if you have the unit on and watch for it to go off. It is easy to miss it coming on and then you have already passed the proper code and have to start over."
If extra distance or sensitivity is needed in the same room, it may not be too hard to replace the IR LEDs in the hand unit with more and/or higher power devices (though the IR LEDs used originally are generally quite powerful) but this would require some circuit hacking and possibly some reverse engineering of the design to determine what is possible. A small convex lens over the IR window on the receiver will help as well but will reduce the angle to the receiver over which response will be reliable. This would be suitable if you always use the equipment from a fixed location like a couch at the opposite end of the room.
Where the transmitter and receiver are both in restricted locations, a short focal length convex collimating lens can be added to the transmitter as well as the receiver. The angular coverage of both receiver and transmitter will be reduced but the range will increase. Reducing the beam divergence by a factor of 2 at the transmitter will increase the range by approximately a factor of 2. Doing this at the receiver as well will add another factor of 2. Several hundred feet should be possible with very inexpensive lenses. I would suggest a lens of around 1 inch diameter with a 1 inch focal length. This is not critical but an IR detector circuit or card should be used to help set up the proper distance to the transmitter IR LED and receiver photodiode.
There are a number of ways of implementing this:
Where at least one video cable exists between the two rooms, a variation on this theme uses a combination of the coax shield and earth ground to send the signal between the rooms.
(From: Robert Scott (Robert.Scott@ncl.ac.uk).)
One of these circuits exists at:
(From: Francis VE2FGS (sonytech@videotron.ca).)
I personally have small pyramids called "Powermid" made by X-10 which work fine.
Those come by pair, one transmitter and one receptor. You plug them in 120 VAC wall outlet and it transmit signals between the two pyramids with FM signals. It work very fine and I think it's the most practical, cheap, and fast way to transmit IR signals from one room to another.
I paid about $40 (Canadian) for the pair.
I know of 2 links to such devices. Try:
Model Carrier Cycles/bit Repeat rate
------------------------------------------------------------------
Emerson VCR 36 kHz 32 10 Hz
Mitsubishi VCR 38 kHz 10 20 Hz
Panasonic VCR 56 kHz 48 10 Hz
RCA TV 56 kHz 28 16 Hz
Sony CD 40 kHz 24/48 20 Hz
Sylvania TV 36 kHz 32 10 Hz
Technics CD 56 kHz 48 10 Hz
Toshiba VCR 38 kHz 20/320* 9 Hz
Yamaha receiver 38 kHz 20/320* 9 Hz
For buttons that repeat, typical rates are 10 to 20 Hz and the entire code may
actually be sent only when the button is first pressed with only a 'repeat'
code sent while it is held down. (* This extra length 'bit' was evident in
the repeat code for the Toshiba VCR and Yamaha receiver - which both seemed
to use very similar coding schemes. Repeat for all keys used a 320 cycle bit
followed by an 80 cycle gap and a 20 cycle bit.) It would appear that various
combinations of NRZ, RZ, PWM, and others are used depending on manufacturer
and model. Think of the challenges involved in designing a universal remote!
The carrier frequency and coding schemes (these are even more varied than the table above would indicate) have apparently not been standardized. They may also vary quite a bit even different models of equipment from the same manufacturer. Therefore, it is beyond the scope of this document to enumerate them all. It is possible to see these types of waveforms with an oscilloscope by monitoring internal signals of the remote including certain pins on the controller IC as well as the IR LED or its driver or across the transistor of the IR detector circuit (see the section: IR Detector and Related Circuits).
Check out ZipLabel.com Computerized Infrared Remote. They have a very cheap and cheerful method of obtaining IR codes. DOS software is provided for textual or binary capture of remote control codes. Windows software for the device is also linked to the site. The Windows software "Monster Clicker" allows you to create any number of virtual remote control functions. This software also has full Macro facilities. It is well worth a visit for the small amount of construction required this is an excellent option.
Here is an even more extensive list:
(From: Joe Krantz (joed.krantz@symbios.com).)
Almost all you can find free from the net you can find linked from
Finally, here is a site that appears to have a lot of more or less non-commercial info on medium to high end (they say) remote controls from various manufacturers including detailed coding and other technical details:
IR radiation falling on the photodiode causes current to flow through R1 to the base of Q1 switching it and LED1 on.
Component values are not critical. Purchase photodiode sensitive to near IR - 750-900 um or salvage from optocoupler or photosensor. Dead computer mice, not the furry kind, usually contain IR sensitive photodiodes. For convenience, use a 9V battery for power. Even a weak one will work fine. Construct the circuit so that the LED does not illuminate the photodiode!
The detected signal may be monitored across the transistor with an oscilloscope.
Vcc (+9 V) o-------+---------+
| |
| \
/ / R3
\ R1 \ 500
/ 3.3K /
\ __|__
| _\_/_ LED1 Visible LED
__|__ |
IR ----> _/_\_ PD1 +--------o Scope monitor point
Sensor | | (low active)
Photodiode | B |/ C
+-------| Q1 2N3904
| |\ E
\ |
/ R2 |
\ 27K |
/ |
| |
Gnd o--------+---------+--------o Gnd
_|_
-
The IR receiver module from a TV, VCR, or purchased from Radio Shack or elsewhere, drives the base of Q1 through R1. It may even be possible to eliminate the transistor circuit entirely and connect the LED directly to the module's output (in series with a current limiting resistor to Vcc or Gnd) but that depends on the drive capabilities of the module. You can use whatever Vcc is required for the IR receiver module for the LED circuit as well but may need to change the value of R2 to limit the current to the LED to less than its maximum rating.
The specific case where Vcc is +5 V is shown.
R2
Vcc (+5) o------+-----------/\/\--------+
| 220 __|__
| _\_/_ LED1 Visible LED
| |
|+ +--------o Scope monitor point
+----------+ | (low active)
-| IR |out R1 B |/ C
IR ---> : Receiver |------/\/\-----| Q1 2N3904
-| Module | 10K |\ E
+----------+ |
|- |
Gnd o------+-----------------------+--------o Gnd
IR receiver diode (from scrap Penney's unit) attached to 18" single pair wires-passed through heavy-gauge straw (from some unknown latte drink in the early A.M.). RTV the tip to maintain rigidity. Positive end to plus end of 9 V battery. Negative end to 330 ohm 1/4 W resistor, and from there to display LED (I chose a pretty red one from the scrap box), and then back to negative of battery.
Time consumed: 2 hours. (1 hour to make sure the RTV was cured properly.)
Application to numerous remote control sources and to a couple of CD pickups provided nice glow from the indicator LED.
I just received a Fisher 25 disc unit for repair, and the above tester was instrumental in determining that over 12 IR emitters were functional. (Some of these were in locations otherwise very difficult to access.)
(From: Raydon Berry (rayberry@pt.lu).)
Measure the current consumption from the batteries. Put the multimeter on a range of about 25 mA and when you press each button, the code being sent will show up as a wagging needle on a VOM or an average current for a DMM. If the ceramic filter or the IR diodes have failed, the current remains very low, but if OK, you should see pulses of 5 to 10 mA.
(From Malik (M.dad@mmu.ac.uk).)
"If you have a IR remote TV in the workshop for testing VCRs and other video equipment, you can modify this so that audio can heard from the speaker which represents the IR signal.Simply couple the output of the IR receiver (in the TV) to the input of the audio output stage. Use a low value ceramic cap and a high value resistor, this should be possible on all remote TV's and will cost you next to nothing."
(From: ShyGuy4Yu (shyguy4yu@aol.com).)
"Take a known good IR receiver from an old set. Supply proper DC to it. Feed the output into an audio amplifier. You can hear intermittent operation really well without squinting at test equipment. Put one on the counter for demo to customers.. Great!!"
(From: Sam).
What a nice idea! The only concern I would have is that not all IR transmitters use the same modulation frequency so I don't know how forgiving the demodulator in the IR receiver would be. Thus, you might think a remote control is bad when in fact it is just incompatible.
You could probably learn to recognize the codes by ear after a while as well! :-)
(From: Paul Grohe (grohe@galaxy.nsc.com).)
"Here is a another "quick" and "very dirty" test of the IR emitter I have used:Clip a *glass* encased diode (1N34, 1N914, 1N4148, etc.) between your scope probe tip and ground clip. Crank the scope sensitivity up to about 20 tp 50mV/div. Hold the diode by the grounded lead (to reduce noise pickup).
Point the "business" end of the remote directly at the clear part of the diode body. The IR packets will now be visible on the scope.
You may have to move the remote around to find the "hot spot" in the window. The more of the diodes junction that is exposed, the better the response.
A Sony remote generates about 50mVpp with a typical 1N4148/1N914 and more than 200mVpp with a "wide open" 1N34A point-contact Germanium (at 1 cm).
BTW, the time constant of this setup may mask the actual 40kHz carrier pulses. Place a 100k resistor in parallel with the diode to see the individual pulses clearly (sensitivity *is* reduced).
Or just simply hold the remote against an AM radio for a quick test."
(From: Sam)
And, Filip also suggested that last one so I will honor him as well. :-) Almost any sensitive amplifier may pick up some clicks from a working remote. A guitar or microphone amp may work for this. However, none of these indirect methods actually test the IR output but probably are accurate enough in most cases.
(From: Filip M Gieszczykiewicz (filipg@repairfaq.org).)
"Simply hold a pocket AM radio or Walkman set on AM and push the buttons. This works for all the remotes I have.... except the ultrasonic one. :-)"
(From: Bob Quackenbush (quackenb@heidelberg-emh11.army.mil).)
"Tune an AM radio to a quiet area of the band, hold the remote near the (normally internal) antenna, press and hold any key on the remote. The sound will be a quiet fluttering, so listen carefully. Be careful with your interpretation of the results. "No flutter" may NOT mean that the transmitter isn't working."
(From: David C. Brink (db@mcs.com).)
"Just dissect the remote far enough to get access to the IR LED(s) leads (if the remote has been through the moving bits of the Lazy-Boy a few times, such disassembly might not even be necessary). Hold a LED in parallel with it and see if it lights when you press the remote buttons."
(From: Sam)
Note: Since the voltage drop across an IR LED is usually less than that across a visible LED, this may not work unless the remote uses two LEDs in series. In that case, substitution may be needed.
-- end V2.96 --