Hi!
Below is a copy of my post in repair group.
I looking for schematics for a RC-receiver IC. 16-pin SMOT (i think surface mount)
On top it says 31136 and the row below 432 (probably the date)
The thing I found is TA31136F from toshiba, it seems to fit quite well, but I doubt it is the right thing.
Regards /Mats
I have a RC-receiver (27 MHz) (Actualy a Mini-Z RC car) that lost the antenna cord. I de-solder the rest of the cord and put a new cord aprox. the same type and length of the original cord. But now the range is about 2 meters maximum (6 feet). I have a ordinary 27 MHz Transmitter that works well on other receivers, and I have test other transmitter with my receiver and that will not help, so it is my receiver (car) that is the problem.
The question I have is could my soldering damage the coil so lots of noise will slip in to the IC if the reception of my signal is weak?
More reading below :-)
Before the car has a range of at least 15 m probably 25 m (depending on room condition). The length of the antenna is not most sutible for 27 MHz, but it is not applicable to have longer antenna than 30 cm. (I have tested though with 80 cm, but with no improvement)
The circuit where the antenna goes in, all surfaced mounted, is like this. Antenna - coil (choke, little black "resistor") - capacitor down to earth - in to IC. (Did you follow).
I have quite good skill in soldering, but I don't know if I might have damage the coil with to much heat.
My guess is that the coil and capacitor is a first filter to suppress other frequency than 27 MHz? When measure the coil it has 0 ohms, as expected, but is they easy to break? I.e. the coil functionality is gone? The Capacitor is not short-circuit, but if it works properly is hard to say?
The IC is an 31136 (the vendor I don not know, but Toshiba have a TA31136F that looks quite simmilar, but I wonder if it could be the same? The most part is a match though, this is fore FM, but I think the transmitter is AM but I dont know, maybe there will be a 31136A)
My theory is like this. The signal is transmitted through the antenna cord and filtered between the Coil and Capacitor in to the IC thats mix the signal with appropriate frequency and out come the 4 channel 1.5 ms decoded PWM signal that the car use. (Standard RC signal) (Out fråm pin 7 if my memory and oscilloscope works properly :-)
Now Mats solder to much and the coil somehow lost the henry, and become a 0 ohms resistor instead. The new antenna work great, but the coil let any frequency pass and the mixer in the IC gets suffed with signals and niose and can't determine what to decode so the car stand still or glitch. (Normaly when only the car is on, it is absolutly still, no sound no humming. When the transmitter is on the car starts so humming, the servo might glitch slightly, now, when both the car and transmitter is on, if I move just 1 meter or so the car starts to do all sorts of thing, stearing, moving, jerking...)
I think that the noise level that the signal has to get up to have increase so the transmitter must be very close to the antenna if it will work.
Could this be the coil that is broken? Or is the IC gone? Capacitor?
I also tryed to hold the antena to the opposite side of the coil, with no improments at all.
One funny thing is that the range improve slightly if I carry the car in my hand, but if I move away from the car it will start to jitter...
Long story, hope you enjoy.
/Mats M.