Problems with new 770PCM receiver.
01-08-2004, 05:18 PM
#1
Problems with new 770PCM receiver.
Hi.
I just recently purchased a 770pcm slimline receiver to use in a 72" GSP Katana. My radio is a 8103DT that is about a year old that has never given a moments trouble. I have 5 fm receivers--two 700's, two r600's , and a 959, all in planes and a chopper that have also been trouble free. The 770pcm range checked fine in the katana with the engine not running, but when the engine --0s160 glow--is running the control surfaces now start moving erratically. The elevators and alierones are setup on seperate channels and mixed for for centering and endpoints. The receiver was wrapped in foam and then tie wrapped to the wing tube. I first suspected vibration so I untied the receiver and just let it hang in the fuse. The control surfaces still moved erratically with transmitter inputs but not quite as much. I changed battery packs ( A new 2700 millamp, 6 volt EXPERT nimh) but still didn't solve the problem, I then plugged the battery directly in the receiver, bypassing the switch, Still same problem --Erratic movement with the engine running, but none with the engine off. I substituted one of my 700FM receivers for the pcm and the problem went away. Any ideas what might be wrong.
I am concerned because i thought with the PCM i would be more glitch and interference free than with the FM, but thats not the case so far even though i know it to be true.
thanks for any help
zonker
I just recently purchased a 770pcm slimline receiver to use in a 72" GSP Katana. My radio is a 8103DT that is about a year old that has never given a moments trouble. I have 5 fm receivers--two 700's, two r600's , and a 959, all in planes and a chopper that have also been trouble free. The 770pcm range checked fine in the katana with the engine not running, but when the engine --0s160 glow--is running the control surfaces now start moving erratically. The elevators and alierones are setup on seperate channels and mixed for for centering and endpoints. The receiver was wrapped in foam and then tie wrapped to the wing tube. I first suspected vibration so I untied the receiver and just let it hang in the fuse. The control surfaces still moved erratically with transmitter inputs but not quite as much. I changed battery packs ( A new 2700 millamp, 6 volt EXPERT nimh) but still didn't solve the problem, I then plugged the battery directly in the receiver, bypassing the switch, Still same problem --Erratic movement with the engine running, but none with the engine off. I substituted one of my 700FM receivers for the pcm and the problem went away. Any ideas what might be wrong.
I am concerned because i thought with the PCM i would be more glitch and interference free than with the FM, but thats not the case so far even though i know it to be true.
thanks for any help
zonker
01-09-2004, 10:10 AM
#2
Senior Member
My Feedback: (22)
Join Date: Nov 2002
Location: Dexter,
KS
Posts: 192
Likes: 0
Received 0 Likes
on
0 Posts
RE: Problems with new 770PCM receiver.
Zonk,
I had a similar problem with a 27% Extra, the solution to which may be relevant in your case. When you swapped receivers from the R770 to the R700, was the receiver antenna routing exactly the same? If not, I would suggest you re-install the R770 with the same antenna routing you had with the R700. In my case, while troubleshooting with different receivers, I discovered that with the original receiver installation, I had installed the antenna too close to some servo leads.
Gary L.
Danny - Just had to jump in... sorry!
I had a similar problem with a 27% Extra, the solution to which may be relevant in your case. When you swapped receivers from the R770 to the R700, was the receiver antenna routing exactly the same? If not, I would suggest you re-install the R770 with the same antenna routing you had with the R700. In my case, while troubleshooting with different receivers, I discovered that with the original receiver installation, I had installed the antenna too close to some servo leads.
Gary L.
Danny - Just had to jump in... sorry!
01-09-2004, 10:30 AM
#3
RE: Problems with new 770PCM receiver.
Yep, same antenna routing, same mounting for both receivers, but with the engine running the servos move erratically with the 770PCM but are ok with the 700 FM. With the engine shut down everythink is fine. If it was a gas engine w/ignition system I would have suspected some kind of RF interference, but since its glow i don't have a good answer.
thanks
zonk
thanks
zonk
01-09-2004, 11:20 AM
#4
RE: Problems with new 770PCM receiver.
It could be a bearing in the engine, or some other metal to metal contact in the airframe. Very odd that the FM receiver is working better though. That may just be random luck. It may be best to send the 770 in for a check up.
01-09-2004, 11:39 AM
#5
RE: Problems with new 770PCM receiver.
danny
Doubt its a bearing, engine was new in the box last week(possible but not likely)
I repeated the setup this morning, same thing, erratic movement with the PCM, i used a different FM receiver this time with the same result--FM works fine. Will you post an address that I can send the receiver too? and should I send the crystal with it?
thanks
Doubt its a bearing, engine was new in the box last week(possible but not likely)
I repeated the setup this morning, same thing, erratic movement with the PCM, i used a different FM receiver this time with the same result--FM works fine. Will you post an address that I can send the receiver too? and should I send the crystal with it?
thanks
