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-   -   servo tester with retracts (https://www.wattflyer.com/forums/showthread.php?t=81048)

jangodog 10-07-2020 03:54 PM

servo tester with retracts
 
Why can i not test retracts on my GT servo tester?One retract got burning hot the other worked a little?
Hope i didn't fry anything. Regular servos works fine.

crxmanpat 10-07-2020 05:01 PM

That's odd. I have an MPI servo tester, and retracts work just fine with it. I don't know if there's something about the GT tester that's causing you this issue. Are you sure you were connecting it with the correct polarity?

jangodog 10-07-2020 05:28 PM

Not sure i connected them properly first time around. But they still doesn't work so maybe i short circuit them and
now they don't work`? I'll try setting up a "power system" on the bench with esc, retracts and rx, lipo and see if
that would work:)

jangodog 10-07-2020 05:52 PM

Don't know much about power setup with esc vs servos and stuff. I have an old eflite 30amp esc i'll try to make work with my temporary "retract" setup. I use a 1800mah 3S lipo aswell
and i can bind to my Spektrum TX without a problem. But only a little jizzer from one of the retracts. The other get's warm again right after i tested it. Won't hook up with more retracts
and destroy them before i know what i'm doing wrong.

Wildflyer 10-07-2020 05:56 PM

May not be putting out enough current to work properly.
My tester has built in AAA batteries, but they can not handle retracts, I use a larger plug in batter then.

jangodog 10-07-2020 06:00 PM

Hmmm, i'll try a bigger lipo then.

Thank's

jangodog 10-07-2020 06:26 PM

Maybe it's because the retract comes from Eflite Viper that runs 6S lipo that they don't work?

Wildflyer 10-07-2020 07:23 PM


Originally Posted by jangodog (Post 1026121)
Maybe it's because the retract comes from Eflite Viper that runs 6S lipo that they don't work?

But they still run off of receiver / servo voltage.
I try to run my retract planes off of a good solid 6 volt battery. Or a big UBEC, not the BEC found in the speed controls.

I had a cheap UBEC go crazy, sending out all kinds of garbage on top of the output voltage. I must have tested that plane with the retracts a 100 times before the maiden flight. Everything checked out, passed my safety inspection, so I topped off the 2 4s 2200mah batteries in parallel, and waited for my turn.
Turned on the system and everything went nuts, servos were going all over the place, the 3 retracts started cycling separately, gear doors out of sequence of course, which burned out the nose gear. I was too stunned to jerk the power quick enough.
Yes the transmitter was on and correct airplane, this wasn't 30 minutes after the safety check (this club requires it for any new plane going out for it's maiden) This one was a total plans built plane, no kit, should have left it with fixed gear. Nose gear burned out retracted so I couldn't just unplug the gear channel and sequencer.

It has a CC UBEC in it now, but I haven't had a chance to try it again.

Hope you get yours working.

jangodog 10-07-2020 07:50 PM

Well i didn't. Must be the retracts from the Viper that are dead. Maybe when i swap them with the faulty ones on the Viper they will come "alive"

Thank's for your inputs.

crxmanpat 10-07-2020 08:24 PM

As Wildflyer said, the retracts don't run directly off the flight pack, they run off the voltage output provided by the receiver (typically 5v). If you are providing more than like 6v directly to the retracts, they will burn up for sure. On my servo tester I use a dedicated 4-cell NiMH pack rated at 4.8v. Powers servos and retracts just fine for testing.

solentlife 10-07-2020 08:48 PM

I have small and medium size Retracts ,,,,, even the huge jobs I have for my 93" Lancaster with heavy legs and big wheels work of common sized ESC -BEC or my 4 cell AA NiMh power pack on my cheapo servo tester.

Here's one leg of that Lanc ... sitting on my 15" Notebook .....

https://i.imgur.com/eMRRiYq.jpg

So I think somethings wrong with your retracts or set-up.

Retracts do not require big power in fact due to the threaded rod system ... even if they jam - the retracts board should shut off power after a couple of seconds to protect the motor etc. But one item that I have never figured out why retracts do not sort ... its possible to insert leg TOO FAR into trunnion and jam it .. but even so - the auto shut off should work.

I have a feeling that you may have a fault where too high a voltage was passed to the retract when first tested ?

Does your servo tester work OK with servos ??

solentlife 10-07-2020 08:53 PM

Some people do setup a separate power supply to retracts similar to gasoline engines where separate ignition supply made. But its based on 5V ..... and actually a hangover from the old days when stalled retracts could drag down RX power if not separate. That does not happen today luckily ... but some people still like to power separately to ensure full power for RX for all other services.

jangodog 10-07-2020 09:31 PM


Originally Posted by solentlife (Post 1026126)
I have small and medium size Retracts ,,,,, even the huge jobs I have for my 93" Lancaster with heavy legs and big wheels work of common sized ESC -BEC or my 4 cell AA NiMh power pack on my cheapo servo tester.

Here's one leg of that Lanc ... sitting on my 15" Notebook .....

https://i.imgur.com/eMRRiYq.jpg

So I think somethings wrong with your retracts or set-up.

Retracts do not require big power in fact due to the threaded rod system ... even if they jam - the retracts board should shut off power after a couple of seconds to protect the motor etc. But one item that I have never figured out why retracts do not sort ... its possible to insert leg TOO FAR into trunnion and jam it .. but even so - the auto shut off should work.

I have a feeling that you may have a fault where too high a voltage was passed to the retract when first tested ?

Does your servo tester work OK with servos ??

Yes, it works fine with regular servos. I think i might have connected the retracts wrong first
time around. Horizontal instead of vertical at the connect pins on the tester. Hope they will
work once in the Viper.

Panther 10-08-2020 03:23 AM

Mine work on my servo tester fine. I power my servo tester through a ESC. using a 3S battery.

jangodog 10-08-2020 09:55 AM


Originally Posted by Panther (Post 1026132)
Mine work on my servo tester fine. I power my servo tester through a ESC. using a 3S battery.

Me too. Both on a 3S with esc and a battery pack 4x1,5V AA tray from my old dx6.

solentlife 10-08-2020 11:48 AM

An old trick ...

Have an ESC that's no longer working throttle ? Most will still have working BEC.
Have an old 2S / 3S LiPo that's no good for flying ? but still usually good enough to power Rx or Servo Tester.

Getting life out of old stuff !!

jangodog 10-08-2020 02:59 PM


Originally Posted by solentlife (Post 1026138)
An old trick ...

Have an ESC that's no longer working throttle ? Most will still have working BEC.
Have an old 2S / 3S LiPo that's no good for flying ? but still usually good enough to power Rx or Servo Tester.

Getting life out of old stuff !!

Great tip there;) By the way i found out the issues on the retracts. The previous owner had a short circuit on his Viper hence the not working issue.
Great i learned that before putting them in my own Viper:)

Thank you all for your inputs.

pmullen503 10-08-2020 08:09 PM

I have a Hobbyking servo tester that won't reliably operate retracts. Was ready to toss the retracts till I tried it on a receiver with an old esc and lipo; worked perfectly.

Had some larger digital servos that did not work well on the same servo tester.

solentlife 10-08-2020 09:43 PM


Originally Posted by pmullen503 (Post 1026146)
I have a Hobbyking servo tester that won't reliably operate retracts. Was ready to toss the retracts till I tried it on a receiver with an old esc and lipo; worked perfectly.

Had some larger digital servos that did not work well on the same servo tester.

That can happen if the items being tested are digitals with different pulse rates ... I have a simple tester - was free gift with something I bought years ago - that cannot test some of the non standard servos ... but my other tester is the HK Red tester and has a switch on the side to set for different rates ...

jangodog 10-08-2020 10:41 PM


Originally Posted by solentlife (Post 1026149)
That can happen if the items being tested are digitals with different pulse rates ... I have a simple tester - was free gift with something I bought years ago - that cannot test some of the non standard servos ... but my other tester is the HK Red tester and has a switch on the side to set for different rates ...

So learned my GT Power tester works after all. Just the retract was toasted:)

jangodog 10-09-2020 09:26 AM

I was lucky i had two extra retracts that also stopped working some time ago. Took them apart and reused the little switches from their faulty pcbs. Holy Jesus they are tiny and very difficult to remove and resolder on the working pcbs. With some tweezers, miniburner and exactoknife i managed to heat up the led and place the two switches on both sides.


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