Itsindilas
Veteran
Location: Greece-Athens
| Exactly the same problem with same srvo and CSM 400 my friend.
A very detailed investigation took place. The problem started when I lost twice the tail in a flight (once in FFF and one in hovering). Both incidences happened after no more than 2 minutes of flying. Before using the 5925 I was using a 925 (NON DIG) with no problems with only one 5945 in my configuration (all else no digital servos). In the same time I upgraded the tail to 5925 the total configuration of my heli was 3 Digitals and 3 Normal servos. (I use a servo for mixture)
1st STEP : I replaced the servo with a non digital 9202 Futaba. Same problem occured but the servo was not taking a position at limits (and it was not blocking, as it happened during the 1st two incidences with the 5925). At the very begining I thought that it was due to vibrations but the Gyro had never had a crash and my heli has the normal vibrations that a heli can have.
Something important, during the investigation (test hovering) the problem was growing up, the more pitch I was advancing up. I was keeping the heli just before lifting to investigate the tail behaviour and with the gyro in Normal moder (no HH). After the passing of 2 minutes the problem was staring again. Notice that the battery is a 1000mah 4.8v and it was fully charged. During the test hovering and proportionally to the Pitch stepping up,the On BOARD volt indicator was becaming too busy and the lights was playing from red to green. (I assess that the servos required a lot of current by draining the battery).
(Several times the same bad behaviour occured with the heli being in a hovering position, 50cm high).
2 STEP: I decide to change the gyro with an old NEJ 130A in order to investigate the case that the gyro has a problem. So, I install and plug the gyro on the heli. As first, I test the heli with the 9202 servo and the servo without touching the any stick (off course the engine was not working) started to play -+5 deg with the heli on the floor of my room (Nobody was touching it). I replaced immediately the servo and the HITEC 5925 was by far more nervous. ( I got completely confused).
I assessed that the rudder channel had a problem, so I unpluged the lead and I pluged it to the aileron channel. The same symptoms for both servos (futaba and Hitec). Gradually I unpluged all the servos from the receiver to test all the channels (Notice that I have tested all the servos connected to their position with the gyro disconnected and everything was normal). Happily the last servo that I unpluged was a digital, at this moment the symptoms stopped. So, I built the impression that the last servo was erratic but immediately this impression collapsed because the same happend with ol the other digital servos that I pluged. The problem didn't occur when I plugged the non digital HITECS. At last, I tested the receiver with the gyro being the only plugged servo and the problem didn't occur in the same strain.
CONCLUSION: The tension of the symptoms is proportional to the number of the plugged DIG Servos. (Eventually, I have already purchased 2 1800 mah NIMH batteries but my APO AE address is not the faster one, so I don't have a battery with such a capacity to test it now). After this investigation I plugged again the CSM 400 gyro to investigate it again. The CSM gyro didn't give any symptom with the heli not running. I was turning with my hand the tail left and right and the Servo was moving left and right, in order to copensate the yaw change.
Eventually the NEJ 130A helped me to find out the instability that occurs when you use a significant ammount of DIG Servos on your heli.
I don't know why CSM doens't give any symptom while the heli is not working but I am almost sure that the DIG servos consume plenty of electic current. Moreover when the heli is flying, plenty of forces (caused either by stick reflections or by vibrations that they reach the servo head through the linkages) reach the servos heads and they spent plenty of amperage to keep on centered or to manouver the heli.
Under these circumstances the most sensitive device onboard is the gyro. IMO whenever the amperage draining diagram is not so flat but is a crooked line the gyro will be affected (even if they say that it could work under a 2.5 v voltage). The problem is not the voltage, the problem is the ability off your battery to compansate high draing rates.
During the phase that I found out that the problem was growing up whenever I was advancing the collective high, I even though that it might be a problem of my stick's potensiometers and that was one of the reasons that I have started checking the other channels and sticks.
Another topic in my case, is that I use a JR 347, quite old, but in mint condition and with non of my RX or servos being participants in an accident. Unfortunately, I can use only the RX in ZPCM mode, subsequently I was not able to test my heli in PPM. Moreover, I haven't any knowledge up to ZPCM and DIG SERVOS. I assume that is not related to my problem. Furthermore, I don't know if the SPCM could eliminate my problem. Happily next week arrives my new JR 10 SXII and I will test both the old RECEIVER and the new SPCM 10 receiver.
So, I will come back with more information about the latest stage of the above investigation. During next week, with the batteries, the new TX and RX, I assess that I will verify my assessments.
I am not an expert and I would be very much appreciated if you correct me or help us ( Me and Ultrasp99) to eliminate our problems. |
