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frsky rb-20

Posted: 11 Mar 2019, 17:48
by jack
Hi all,well,l have progressed the B4 to the gear install stage,l have just fitted my new RB-20 redundancy bus,but it seems like l have a problem with it,at first all seemed fine,my u/c and doors were going up and down in fine style....then my tx started shouting at me,warning power overload-servo overload,which it kept repeating.....this got my attention,it not being something l had set up or even heard before :o ,investigation followed,but all seems to be fine,this warning is produced even after l pulled all the servo plugs from the rb-20 :? ,l also removed the back up power lead so l know its not an overload,the fact that the warning happens even when no servos are connected is worrying :? ,does anyone have any ideas as to the cause :?: ,the instruction sheet states that the rb 20 does have overload protection on each channel,but l cant see why its activating with nothing but the power lead plugged in and only supplying 6 volts...maybe my rb-20 is faulty :?: any frsky gurus out there have any suggestions :?:

Re: frsky rb-20

Posted: 11 Mar 2019, 19:15
by Barry_Cole
Jack,
I will inquire, of those that know these things.

:D :D :D :D

BC

Re: frsky rb-20

Posted: 12 Mar 2019, 14:31
by Simon WS
It would be unfair of me to "rubbish" a product based on one experience (and in general I love Frsky products) but a friend of mine used the RB-20 in his 7m Let glider and lost complete control on the maiden and the model was partially destroyed. He is convinced that the RB-20 was to blame but obviously we can't be certain.
Personally I go for a simpler route when I need lots of channels by using two receivers each with their own battery and build in as much redundancy as possible (one elevator for each receiver etc)

Simon

Re: frsky rb-20

Posted: 13 Mar 2019, 19:25
by jack
hi people,an update on my RB-20 troubles,so far neither myself or barry have been able to come up with an explanation for this problem,richard at T-9 has been really helpful,couldnt ask for better response from a supplier,but,l still have a unit that l cant trust....the fact that the "power overload and servo overload" are still generated even after unplugging everything bar a single power lead suggests to me that its an internal fault,l updated my Tx to the 2.2.3 release but this made no difference.....l have now returned the unit to T-9,for replacement,l have asked Richard to let me know the outcome and will post it here,Simon,l have just read your reply post and its a bit concerning to say the least :( ,but like you l do like frsky stuff,it would be of interest to hear from people who may have had incidents with the RB-20,anyway,l will be having another as soon as Richard can supply one,will let you all know how l get on :!: :!:

Re: frsky rb-20

Posted: 13 Mar 2019, 20:17
by Barry_Cole
There are plenty of posts on RC-Groups from people who are using them very successfully on large IC planes and fast jets.

:D :D :D :D

BC

Re: frsky rb-20

Posted: 13 Mar 2019, 22:15
by Elliot Howells
Interested to see your prognosis, I have an RB-20 waiting for a model...

Ell.

Re: frsky rb-20

Posted: 14 Mar 2019, 07:47
by Cliff Evans
Have you checked to see if there is a firmware update for the unit itself!

There is also a thread on RCGroups that may help with the problem, https://www.rcgroups.com/forums/showthr ... st40597131
The user there with the user name of "webbsolution" may be able to help as I beleive he has written some of the firmware for FRSky.

Re: frsky rb-20

Posted: 15 Mar 2019, 20:17
by jack
Evening cliff,had a look on rc groups,the problems are more or less the same as those l am having,in my case l was getting the warnings as soon as l switched on....even when l had nothing but a single 6 volt feed connected :? ,l checked the voltage being supplied and got about 6.80 on a freshly charged nimh pack,these units are rated up to 8.4 volts so it was definitely not overloaded,its gone back to T-9 now,hopefully Richard can get to the bottom of it,presently l am using an x8r to set things up with no trouble at all,so ,as far as l can see,its all pointing to an internal fault of some kind in the RB-20,possibly related to the overload protection on the channels :?: ,all the best,jack.

Re: frsky rb-20

Posted: 02 Apr 2019, 15:20
by jack
Ok,it seems that the saga of the misbehaving RB-20 has finally been resolved...l have everything plugged back in,and, so far,no frantic warnings :D :D :D ,what was the magic cure??,l splashed out a bit and fitted High Voltage servos all round (7volts +),l have no idea why that fixed the problem,but it seems to have worked the charm,so l am more than happy to take it and be thankful :) :) :) ,to all those who offered help and advice l offer my deepest thanks...barry,cliff,thanks so much guys,and to all you other forumites very many thanks,its good to know theres help out there when needed.....jack.

Re: frsky rb-20

Posted: 02 Apr 2019, 16:04
by FrankS
Jack, glad you got it sorted, reminds me of a time with a small electric autogyro, plugged the battery in and it glitched and then stopped working, first thoughts were faulty Rx (Spektrum) or ESC BEC, it turned out to be one of the 4 savox servos was drawing a lot of current and causing the BEC to cut out. Plug in a regular Rx battery and everything, inc that servo seemed to work OK, we returned the servo to the shop, they returned it saying they had tested it and it was OK. Autogyro flew fine (well OK :lol: ) on same Rx and ESC with that servo replaced.