I have had difficulty with this remote starting about 1 month after I bought it. It worked erratically, but well enough to keep it. Recently I discovered that ALL my remotes in my theater were acting erratically. I grabbed my camcorder and looked at the remote's RF base unit and IR blaster. They both are spraying out IR, even when the remote is not being used. This IR bath makes ALL the IR receivers in its path unreliable. Has anyone seen this problem and is there a fix? If not, is there a schematic available so that I can fix it? TIA!

If there's alot of RF noise in your area, this is the side effect that happens. There really isn't a way to fix it (that I know of).

What you could do is turn the base unit off (or turn it around) when you're in the main room, and just use it when you need the RF extension.

Rob
http://www.hifi-remote.com

Thanks, Rob. I have since learned that I'm not the only one with this problem. Most have given up, but It think it can be fixed. The ciruitry is very simple -- I may have to just trace out the schematic. It looks like they have a threshold too low on the LED solid state switch or the data slicer. The low cost designs often sacrifice beta and temperature stabilized biasing, which can be easily fixed (if that is the problem). When they ommit the bias stabilization, you get variations in performance with temperature and across production lots. I was hoping someone had already fixed this or at least, had a schematic to make my job easier.
Regards,
Dean

If you think you can engineer a fix for this, that would be great, we're all about customizing these remotes to work just the way we want them to.

You can get a schematic of the remote here...
[Link: hifi-remote.com]

Rob
http://www.hifi-remote.com

Rob,
I checked the site and it had a schematic for the remote, but I didn't see anything for the RF receiver base. Does it have a different part number?
Thanks,
Dean

I finally got around to tracing out the circuit board and creating a schematic for the RF receiver. I have fixed the problem in my receiver. It works great now. I have not gone back to see how much margin there is or whether the RF range has been reduced -- in my 28'x14' theater, the range is sufficient.

I don't recommend this mod for those who can't solder a chip resistor. For those who can:

1. *** UNPLUG *** the receiver from the wall.
2. Pry off the four rubber feet on the bottom.
3. Remove the four philips screws at these locations.
4. Separate the cover and front lens.
5. The board can be lifted off the mounting bosses and flipped over to expose the bottom.
6. Replace R24. It WAS 330K. Change it to a 240K. The resistor is an 0805 sized package -- I used a 5% part. You could alternately solder a second resistor across this one, leaving R24 in place. If you do this, use a 910K resistor and solder it across R24. You can even use a leaded component, if that's more readily available.
7. Reverse the disassembly instructions 1-5 above.

This mod lowers the data slicer threshold at the input of U2 (pins 12/13). The original value had this reference too high so that noise from the RF receiver would sporadically turn on the IR emitters. In doing this mod, the AC (data signal) gain from the receiver is also reduced VERY slightly. For that reason, it may reduce the sensitivity in applications where the remote is being used at the limit of its range. Sorry, there is no help for this situation. For the rest of us who love this remote and have a closer proximity to the receiver, this should do fine. I have only short term testing, so it is also possible that time will age the parts and further change the data threshold. A variable resistor would allow adjusting the value for varying component tolerances, etc. I should wait until longer term testing is done, but I will have lost interest by then and I wouldn't write this up so that others can benefit.

There are no promises or guarantees with this mod. It works for me. I assume no responsibility for your modification according to these instructions. If you don't physically damage your board (just be careful!), you can always return the receiver to its original state with nothing lost.

Cheers!
Dean

for most this is the way to go. a 1/8 watt resistor with sapagetti over the leads is much easier to deal with than a chip .
even then this is only for those with good soldering skills

>>>>You could alternately solder a second resistor across this one, leaving R24 in place. If you do this, use a 910K resistor and solder it across R24. You can even use a leaded component, if that's more readily available.

bought one exchanged it due to high battery drain and high backlight noise

RS showed a another store close with 2 in stock, one package was opened , so I passed on that one, now I have 2 , I need to mod one of the receivers due to noise




This message was edited by nedbal on 06/26/04 21:40.

I missed Dean's post when it first came around, so I'm happy to read it now. I will file this one away because the noise problem is a common problem.

However, when I tried using the RF feature of my 15-2117, the problem was that the RF signal emitted from the remote was too weak to make it all the way to the base station. It had to travel through some closet doors that have mirrors on them, and the metal in the mirrors was too much for the signal.

So, if anyone has any ideas how to improve this situation, I'd be interested in that also.

Thanks,
Rob

I have a spare base station for the 2117 if either of you guys would like one to try different things on.

I too had problems with the IR noise. But in my case it only effected the Cable TV box. This of course was discovered painfully as the IR blasters from my Replay were rendered inoperative by the IR noise from the base and I missed a few shows (thankfully, I was able to have someone send them using Replays internet show sharing).

Anyway, my solution was simply: upgrade to digital cable, get a new box, and hope for the best. Glad to say this worked. In the meantime, since we often use the RF remotes from the deck or other rooms (for music control mostly), I decided I would pick up another one and now I have a second base station that I could probbably live without.

Of course, if, at the conclusion of any and all Frankenstien type testing, you are left with a working product, I guess I also wouldn't mind having it back.

If anyone is interested, email me at plyons AT optonline.net

This message was edited by plyons on 07/17/04 09:29.

Here's some notes I looked up when I opened it and did the mod , the 3 lead device that drives the led's I couldnt track down, most likly a simple pnp or npn.

I did not open the RF can


[Link: rds.yahoo.com]

National P/N LM78L05 - 3-Terminal Positive Regulators
LM78L05 - 3-Terminal Positive Regulators
[Link: national.com] - 36k - Cached



Generic P/N 78L05 General
Description Features Datasheet Package
& Models Samples
& Pricing Reliability
Metrics Design
Tools Application
Notes

Parametric Table Parametric Table
Temperature Min (deg C) -40
Temperature Max (deg C) 85
Multiple Output Capability No
On/Off Pin No
Error Flag -
InputMin Voltage (Volt) 6.70
InputMax Voltage (Volt) 35
Output Current (mA) 100
Watchdog -
RegType Linear Regulator
Output Voltage (Volt) 5




[Link: fairchildsemi.com]

CD4093BCM
Quad 2-Input NAND Schmitt Trigger


General description

The CD4093B consists of four Schmitt-trigger circuits. Each circuit functions as a 2-input NAND gate with Schmitt-trigger action on both inputs. The gate switches at different points for positive and negative-going signals. The difference between the positive (VT+) and the negative voltage (VT-) is defined as hysteresis voltage (VH).

All outputs have equal source and sink currents and conform to standard B-series output drive (see Static Electrical Characteristics).

Nedbal,
I haven't been back to this forum for a while. I see you tried the mod. Is it working well for you? Mine continues to be cured. Thanks,
Dean

For anyone who might be interested, there is now a hack published that lets you work the RF box that comes with these remotes in countries that don't use the US standard 110 volts:
[Link: hifi-remote.com]

Is it the same hardware modification for the OFA 9910 ?

Whatever can be done to the 2117 basestation, can be done to 9910's.

I have seen 224 written on the R24 resistor, is it correct ? Should it be 330 ?