PCM lock out servo mvt

[Troy A. Newman]

Nope Sorry Bob,

The PCM S used on JR radios today doesn't allow it to be turned off.
You can set it to hold or set it to a propositioned F/S location but that is
it. Works the same as the Futaba stuff. Now there is an older version of PCM
that JR still supports called ZPCM the Z was a 512 PCM and it allowed you to
set the time delay before it kicked in. And it could possible have been a
turn off thing....I'm not really sure on it as I never ran ZPCM.

One thing to look at is a bad servo. I had this the amp in the servo when
bad somehow and it was feeding back into the RX. This just happened this
year a few weeks ago. As I would get toward the end of range maybe 70% the
response of the servos...servo response was delayed, even choppy. I would
set full left rudder as F/S so I could see it out 100-150 paces. I then turn
he rudder back to hold. Only f/s I run is low throttle when
flying........Well it would be in F/S full left rudder and I could move the
ailerons and elevator.
Needless to say I got really nervous this is the first time I have any type
of hold condition or anything with my JR stuff in over 5 years of running
it.

I was running dual elevator servos...3421SA's Seemed one of them was a
little raspy when it moved...I unplugged that servo from the RX and
everything went back to 100% normal.

On the 10X I can now walk 150-200paces antenna off and still have great
range. I was still concerned so I pulled RX, Lead, and RX sent the servo and
RX back for service. The RX was excellent no problems the servo had a bad
amp or something. I'm going to run my range test again as its now installed
back in the model....But this time I replaced the dual elevator servos with
a single one and the CF pushrod DEPS thing from Central.


Next issue JR and Futaba both send their "failsafe" signal about once every
15-30 secs or so. I never counted. But if you turn everything on...and the
system has not sent the F/S signal yet...then when interferance happens the
PCM will not know what to do. So here is my suggestion. Turn TX and RX
on...let it stay on for about a minute....then turn TX off and wait. to see
what's up.

A common source of interference is bad leads. If you have servos in the
tail...look to the extensions you are using. Are they the HD gold ones. We
have gotten lots of reports and I have seen it personally a bad lead can
make funny things happen from servo oscillations to a servo running slower
than another servo of the same kind.  This is on both types of radios Futaba
and JR. As Cronkite says send it in for service to make sure the RX is OK.
I would not fly it in the current condition.

Hope this helps
Troy Newman
Team JR



----- Original Message ----- 
From: "Bob Richards" <bob at toprudder.com>
To: <discussion at nsrca.org>
Sent: Thursday, March 10, 2005 7:30 AM
Subject: Re: PCM lock out servo mvt


> Ed,
>
> I'm no expert on JR radios, but I'll take a stab at
> it. If anything I say is not accurate, someone please
> correct me.
>
> As I understand it, the JR radios allow you to turn
> off PCM altogether, which means that it will try to
> respond to whatever signal comes along, whether it is
> a real signal or interference.
>
=================================================
To access the email archives for this list, go to
http://lists.f3a.us/pipermail/nsrca-discussion/
To be removed from this list, go to http://www.nsrca.org/discussionA.htm
and follow the instructions.