I've got an old stereo that doesn't have a remote control. There was a model that did, and after looking at the service manual it looks like I just need to populate a PCB with an IR receiver to add that functionality. However the part isn't available in quantities smaller than 1000. I think I found one that has pretty similar electrical characteristics. What are the chances this could actually work? And yes, I realize I will end up spending a lot more effort attempting this than just getting off the couch and turning down the volume.

Some details: radio is a Sony CFD-G30. The CFD-G50 is the version with a remote. The service manual is very detailed. Here are some relevant images:

I haven't cracked it open yet, but looking at those images it looks like possibly I just need to add the IR receiver a couple resistors and capacitors and a \$.05 transistor (KTC3198GR-AT). The IR receiver called for is NJL63H400A which I can't find stock for but the one I found in stock for single quantity is RPM7140-H8R.

I'm most interested in knowing whether IR receivers are pretty interchangeable or if there's a lot of tuning at the micro-controller level to work with a specific part, which would make this endeavor quite fruitless.

• I doubt the manufacturer left out only the IR receiver. There is also probably at least a small IC to process and filter the incoming signal before handing it off to the main processor. Without knowing more about the unit (model number, schematic, etc.) I'm going to say the chances are very low. – JYelton May 11 '14 at 23:06
• Added specifics. I'm mostly curious to find out how interchangeable IR receivers are. – schlazor May 11 '14 at 23:48
• In addition, it may require different firmware for the (assumed) microprocessor to handle the output from the IR receiver. – DoxyLover May 12 '14 at 4:21

Note: It is unlikely that the IR receiver substitution alone will suffice, supporting passive part values may need to be tweaked as well.

The NJL63H400A is an 11 mm aperture, metal cased, top-facing (63H) 40 KHz (400) long-range (A) modulated IR receiver, with optimal reception wavelength of 940 nm +/-50 nm.

In order to find a replacement for that part alone, the casing may be disregarded, as the 5 different types of casing in the series are primarily cosmetic and mechanical variants. This particular one has snap-fit legs besides the 3 pins.

Parameters to match:

1. Pin-out: Out, Gnd, Vcc needed to fit the existing board design
2. Carrier frequency: 40 KHz, important if the same remote control is to be used as in the original. If not, the very common 38 KHz receivers are typically cheapest.
3. IR wavelength: 940 nm is very common, it would actually take effort finding a receiver far off this wavelength
4. Supply voltage: The original specified part is rated for 6.3 Volts, while 5.5 Volts is a common specification - so it is worth checking what actual supply voltage is used in the existing circuit design.

One of the several Vishay Semiconductor molded IR receivers designed for 40 KHz could be used, if the carrier frequency is to be kept the same as in the service manual. Those have fairly similar lens aperture and operating parameters. For instance, the 40 KHz versions of TSOP4140, TSOP4340, TSOP4540 may be suitable, but not the TSOP21xx, TSOP23xx and others listed in the same datasheet, due to having a different pin-out.

For greater reception range, use an elliptical lens extended range version (F series) of the receiver, similar in optical angle specification to the original part. The F series is less easily sourced, though.

In general, IR receivers are fairly interchangeable as long as the operating parameters mentioned are met. Of course, if cosmetic / mechanical compatibility is desired, that is a challenge in itself.

• Thanks for the answer! I'll crack it open and see if the PCB is indeed just not populated and then contemplate my next move. – schlazor May 12 '14 at 4:29
• The recommended operating voltage is specified as 4.5 - 5.5 V, which matches most common IR receivers. – Wouter van Ooijen May 12 '14 at 6:33