KST 08 servos

[Guest]

So, over on RC Groups they are discussing the quality and life of the KST 08 servos and they seem really hit and miss. But there are a lot more USA dlg fliers than there are UK fliers so naturally problems may show up with more of them being used over there.

You guys here in the UK using them, how are you finding them? i had 4 in Blaster 3 but i didn't own that for very long and have 4 for my Vortex. But, if they are becoming a bit hit or miss, i would rather not finish the build with them and use something else, i'd rather go to something not as well spec'd but that's going to last, rather than use a servo that is great on paper but you just don't know if it's going to fail and put your model in the ground.

Out of the first 4 i bought for my Blaster, i did pull 2 out and swap them as they had play in the gears at centre, the other 2 and the 2 new ones i ordered were nice and tight, the sloppy ones are currently in the Vortex to be used on the tail end with pull springs. But like i said i don't know now if i want to carry on the build with them. Id rather put the SD100 on tails but would need something that will fit in the wing.

How have you guys found them? any failures or issues?

[Richard Swindells]

I had zero returns out of the first batch

7.5% returns from the second batch . I have another batch in transit to me right now.

Compared to my 100% failure rate on a batch of 20 mks servos a couple of years ago it's not so bad.

[Guest]

Superb, thanks Richard.

I'm gonna stick with the KST, ive powered mine up and gave them a wiggle for a short while and all seems good, plus they fit in the model lovely =)

Those i had off you were perfect, no slop in the gears, so since i put the ones with play on the pull spring tails, i have 2 spare should any issues creep up.

Thanks buddy, hope to fly with you guys soon

Mark

[Martin O]

So far I've used 8 KST's, combined with my friend who has built the same models, 16 between us. We've had no issues with the servos themselves but we have come across a few of the supplied plastic arms that have been sloppy on the splines. it appears to be a manufacturing fault with the way they were molded. It does give the appearance of sloppy gears so if you haven't done so already, it might be something worth checking Mark. We are about to build an NXT each and plan on staying with them.

[Martin O]

#40 is very interesting

http://www.rcgroups.com/forums/showthread.php?t=2630116&page=3

 

[Guest]

Yeah i just read that, guess a dab of hot glue can't hurt for a little extra security.

From past posts, it seem the ones that failed the most were ones where people had removed the lugs, so bending the wires out the way while handling and removing the lugh could have easily pulled them inside if the soldering is a little weak like Thomas says.

Guess we;ll now have to wait and see if the issue goes away. Mine all work great that i had off Richard, but i will add a dab of hot glue on the exit of the cases on mine just in case.

[MikeDLG]

Had my first KST X08 issue the other day. Went to fly, switched on and the rh aileron and elevator were dead - as if not plugged into rx. Disconnected and reconnected battery and they came back to life. I flew for about an hour without issue. 

A bit worrying. Means I am going to have make sure I check that each surface is moving correctly after each power on, not just wiggle the sticks and throw it!

I am using 2S unregulated into a FrSky RX (FASST) with 4 X08's.

[cirrusRC]

this is the "boot" issue.   As per the thread on RCgroups doesn't necessarily mean your going to get a failure - but doesn't exactly fill you with confidence right!

 

[Guest]

Yeah this is really worrying me now. I haven't finished the Vortex and I'm now thinking of going with SD150 in the wing and SD100 in the nose for the tails. 

There's even less dlg fliers in the UK than over the pond and the fact a issue has came up for one of us doesn't look good on these servos?

[Guest]

Same issue as Mike Stern, yesterday 27th Apr. Powered up and RH AIL servo was dead on Tony Hicksons old XXLite running rudderless on 3 X08's version unknown. Instal is in the pod with pushrods.

MPX 2.4GHz Cockpit TX

MPX RX5

600mah 1s Nano tech Lipo  fully charged

2mm Bullet battery  connectors on silicon conductors, no telemetry, no altimeter, no mag switch

Second time this has happened, first time 4 months and 12 outings ago

Put the wing covers back on the XXLite and flew a Smile (4 x X08's) without issue.

Returned home found a spare new X08 to replace the duff servo but connected up again . The wretched servo started to function OK. Put the wrong doer on servo tester for 20mins, still OK. ...don't you just hate intermittent faults? Researched the failure on RCGroups, learned of the 'boot' issue. Have just put 4 Hyperflight V3 X08's in a  Stream NXT......... Its going to have to wait for a solution before I dare fly it. The manufacturers are not exactly falling over themselves to solve this issue. It ought to be in their best interests.

Regards Ian

 

Mea culpa, I had to edit this post as I saw a motor poking out of the base of the servo and assumed it was an X08. Tony H advised that he built it with MKS 65, so disregard above...I have a bad connection not a 'boot' issue.

Edited April 29, 2016 by Guest
wrong assumption

[cirrusRC]

thanks for the additional report Ian.    Mine behave perfectly on the servo tester but I'm wary to say the least about sticking them in my model.

Wild stab in the dark here - could this be something to do with gauge wire and length of wire used for servo leads?    Mind you - if you've gone 4 months between the boot issue this is very intermittent indeed.   I'd put up with a boot issue if the servo's were otherwise reliable - but reading on RCG that doesn't appear to be the case.

The manufacturer reported a defect had been found with the wiring entering the servo (not secured properly) - but people who'd had failures checked the wiring and reported no issues........

 

David

[Marin Mitev]

I had these problems last season. First I noticed that my Akcent is not roll responsive (intermittently) but I thought,... may be it is just me. Then on a low pass I noticed that just one aileron was moving. However after landing,... all was OK. The shock for me came when after launching the model I had both ailerons not working. I managed to land the plane safely and after the sudden deceleration,.. ailerons came back to life as nothing had happened. It was very annoying because the ground tests were OK. It happened just after launching (intermittently). Then I decided to replace the Hitecs (HS-5045HB) with KST 08 servos and I still had the same issues. On one of the competitions ( Hockliffe ) I had one of the ailerons moving the whole travel up and down just before we start a task. I had to replace the model but after unplugging and plugging the power all was OK so I decided to carry on with the Akcent. Later after the end of the season I tried to analyse what was wrong and I came to a conclusion that the spring loaded connector ( Mill Max ) is causing that. I ordered it from USA because I didn't find something similar here in UK. Before that I had 3 years of no problems (before 2011) with similar type connector ( I took it from an old GSM phone ) which is the smaller connector on one of the photos. The model was fitted with Diamond D47 servos (SD100 analogue ). These servos are not digital. My opinion is that the launching of the model ( the physical stress ) is causing slight movement between the mating parts of the connector and may be electrical noise which digital servos don't like. I didn't say anything when Mike offered spring loaded connectors on the forum because they are completely different design and I thought that their contact surface is much bigger hence more reliable.

I replaced the Mill Max connector with Deans micro plug and socket and I had no issues since then.

Here are a couple of pictures showing the type of the connector I used to use.

 

[Richard Swindells]

the best bet is to return any faulty servos to the vendor (or me if you bought some from the group buy and I will get replacements.). 

I have had a few servos returned with pot/bad connection issue, but these are the first reports of the reboot problem that seems more common in the states. There are no reports of "reboot" issue servos failing in flight, to my knowledge (yet).

I do understand that the manufacturers are aware of the problems and that there should be some update from them soon.

[Guest]

I'm correct in saying there have been no reported cases of these servos failing in flight? Just them not powering up on initial power up? 

I think I will carry on and fit mine if it's only a power up issue.

SD100 servos are no good in the wing are they if I were to go with something else? I don't think SD150 will fit will they?

[Richard Swindells]

Hi Mark,

There are two issues

1. Reboot issues, no reports of any in-flight occurences .. OK to carry on and use if you are prepared to be vigilant when you turn on

2. POT/wiring/Centering issues. Intermittent, can occur in flight, although all reports so far are that people noticed the issue but decided to carry on flying. Some of these pilots have lots models... The servo vendor is not responsible for replacing damaged models! If you have noticed any strange centering symptoms at any time then stop flying, remove the servo and send it for replacement.

I am flying with these servos, and have not experienced any issues myself so far.. but am being very careful to keep an eye out for potential problems

[Guest]

I had the kst 08 in my First Blaster 3 and for the short time i owned it i didn't have any issues.

I'm sure the amount these servos that have been sold vs the amount of people hitting the forums with problems makes the failure rate quite small? But i shall continue to fit them i think and just keep a close eye on them like you said.

Thanks Richard 

[Richard Swindells]

I also want to add that the supplier is fully aware of the issues and we are expecting a response from the manufacturer soon. I will make sure that all faulty servos returned to me are either refunded or replaced.... but am just holding off processing all the returns until the manufacturer has arranged how they are to address the problem

[Martin O]

On 29/04/2016 at 07:36, Richard Swindells said:

I also want to add that the supplier is fully aware of the issues and we are expecting a response from the manufacturer soon.

I wonder if the manufacturer is holding back production whilst adressing the issues. HF have been out of stock for several days now and I could do with four.

[Richard Swindells]

Judging from the rcgroups thread, something upset HF and they did a public "unsubscribe" from the thread. I have no idea if that means they have withdrawn support for the servos or not.

Just use armsoar.com for KST servos. No quibble returns, with a better price and service. Thomas Lee (who owns armsoar) probably does more to support, sponsor, promote and develop f3k than anyone. 

For those who took advantage of the group buys on here, I am handling the returns. (Our servos were bought through Thomas)

[Martin O]

Thanks for the info Richard but I'm a little confused. On the Armsoar Web site I don't see any x08's but there is a DS-245s servo with what appears to the same dimensions and similar torque. Is this something new or just a different servo?

http://www.armsoar.com/collections/servos/products/ds-245s?variant=1143890061