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Sep 13, 2019, 04:05 PM
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JohnM's Avatar
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1.7g Low Voltage Micro Digital Servo


The flying club I joined earlier this year also has an indoor flying site that will be available starting the last week of October and I am in the process of building some of the micro balsa aircraft kits available from Banggood. I have started on the Sopwith Pup and I ordered some of the 1.7g Low Voltage Micro Digital Servos ( https://www.banggood.com/1_7g-Low-Vo..._warehouse=USA) and a couple of the 2.4G 4CH Micro Low Voltage DSM2 DSMX Compatible Receiver Built-in Brushed ESC ( https://www.banggood.com/2_4G-4CH-Mi...r_warehouse=CN )

It appears that the connectors on the servos are not compatible with the connectors on the receiver.

From the excellent JST sticky thread ( https://www.rcgroups.com/forums/show...the-real-story ) I believe that the servos have the "Molex PicoBlade" connectors with 1.25mm pin spacing and the receivers have "JST-SH"connectors with 1.0mm pin spacing.

It appears that I didn't do enough research prior to placing my order. From the recommended parts listings and links as well as the "Frequently Bought Together" links, I arrived on the page for the wrong version of the servos. There is indeed a version of the servo with the correct connector
TY Model 1.7g Servo With JST 1.0mm Plug Compatible Spektrum 6400 Series Receiver For RC Airplane
https://www.banggood.com/TY-Model-1_...r_warehouse=CN

Unfortunately, I ordered two 4-packs of the servos along with 2 receivers. I ordered 8 of them as I have read some bad reviews on them and figured I could at least get 4 good ones out of the 8. Luckily I do have some compatible connector leads with the correct connector that I could soldered on to the existing servo cable, but I am debating whether to just unsolder the servo connectors from the receivers and solder the servo wires directly to the pads.

Since shipping from Banggood can range from a short time to a very long time, I am hoping that this post help others to avoid making the same mistake I did.

Another question I have is if anyone can recommend any of the linear servos available from Banggood as an alternative to these 1.7gram rotary type servos. I am looking forward to building more of these kits and have 4 more on order. The Fokker Dr.1, Cessna L-19, Fokker E3 and the Flea.
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Sep 13, 2019, 04:25 PM
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Steve Joblin's Avatar
Is this what you are looking for? https://www.banggood.com/1-Pair-Gote..._warehouse=USA
Sep 13, 2019, 05:05 PM
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JohnM's Avatar
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Quote:
Originally Posted by Steve Joblin
Yes, linear servos, but I am looking for recommendations from someone that has used them.
Sep 13, 2019, 06:47 PM
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AntiArf's Avatar
Quote:
Originally Posted by JohnM
Yes, linear servos, but I am looking for recommendations from someone that has used them.
I've used the GoTeks on several models, with no failures like I've had with Spektrum ML servos. I've had a few that move a bit slower than others, so probably a good idea to have a few spares on hand, but again I've had no failures using a D1N diode drop with 5V BECs. If I have one that's a bit slower than the others, I'll use it on a rudder that's mostly functional just for scale detail anyway. This Sterling Fokker D8 is one of the models I've built using Gotek servos: https://www.rcgroups.com/forums/show...n-Flight-Video

At this point I've used more 5320-5330 servos from various distributors than I can count with diode drop on 5V BEC, and have had no failures using them on models as large as a 34"airliner on ailerons. I've gone to them versus using the Goteks, but there are things that can be done with Goteks that are difficult with the larger standard servo package, such as squeezing them into wing ribs. I can see why people like the UM servos, as most probably wouldn't care for the intricate modification to wing ribs required for mounting a standard type servo. The Guillow's Cub below is a good example of that type of tight installation.
Last edited by AntiArf; Sep 13, 2019 at 07:03 PM.
Sep 13, 2019, 07:27 PM
Registered User
I'd recommend direct soldering; the weight savings is decent and it is a solid connection with a custom length.

I have a couple of the linear servos but have not fitted them. They seem ok but the 1.7g rotaries are just great. I combine the +/- wires and pull the backs off (drop of glue on the motor case) for less weight. Will try litz wire at some point.
Sep 13, 2019, 10:33 PM
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AntiArf's Avatar
Very true about scrapping connectors for solder. I rarely use servo extensions (reliability issue also) on models under 4', which is most all of what I build. At around 24" and under, using standard S-connectors is like throwing bricks into your model. The 1.5mm JST is a good compromise for lightweight, also large enough to fairly easily make harnessing unlike 1.0 JSTs, although I would now have to order direct from Lemon to get the receivers as resellers don't seem to carry them. Also recently discovered that the JR colored 32AWG Maxx Prod servo wire has considerably lighter insulation than the Futaba colored wire. Wire weighs. I won't use anything heavier unless maybe for a 9gm or heavier servo driving 3 retract units.
Sep 14, 2019, 02:52 AM
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jj604's Avatar
John, for what it's worth.

I have found the rotary servos more robust and reliable than the linear ones.
They are less likely to be damaged by over driving, they have better torque and they don't get dirt and grit in them.

The linear servos integrated on the 6400 style brick are often easier to set up for an RE plane and lighter overall however.

Hobbyking also sell these servos.
The Molex Picoblade 1.25mm version is this one
https://hobbyking.com/en_us/hk-5320-...c-0-075kg.html

The JST-SH 1.00mm version is this one.
https://hobbyking.com/en_us/hk-5320-...0-075kg-1.html

The only difference in the number is the S on the end.
These servos (and the TY versions I suspect) are all made by the major servo OEM manufacturer Dongguan Pingzheng Science Technology Co. Ltd.
A LOT of the various brands of servos you will see around are made by them.

John
Sep 14, 2019, 12:37 PM
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JohnM's Avatar
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Thanks everyone for the info. I will probably go with direct soldering of the servos.
Good to hear some positive feedback on the micro rotary servos. They are tiny but the servo tray in the Sopwith Pup is designed for them as seen in the photos below.
BTW, this aircraft is tiny compared to my UMX planes.
Sep 15, 2019, 05:53 PM
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crossup's Avatar
HK also sells converstion cables, I have nearly every combo of 1mm, 1.25 and 1.5mm from them, mostly because then I can take advantage of deals where the servo/esc/rx doesnt match what I would prefer to hook up to it.

Also they sell or have sold the pieces parts to make sell the JST and an Molex micro connectors, the crimper they sell doesnt handle all three main sizes directly but its easy enough to adapt and of course one can alway just solder them and trim the parts the gets crimped inward so they fit into the plug.

And lastly some BlueArrow servos like the 303 come with adapter cables which is a nice bonus if you need something the size of the 303.

Pic is for 1.25 servo to 1.0 rx adapter cables. CAUTION, alway make sure the pin outs are the same and if not its easy to pull the pin/socket and move them into proper order
Last edited by crossup; Sep 15, 2019 at 06:10 PM.
Sep 18, 2019, 11:39 PM
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AntiArf's Avatar
Quote:
Originally Posted by JohnM
Thanks everyone for the info. I will probably go with direct soldering of the servos.
Good to hear some positive feedback on the micro rotary servos. They are tiny but the servo tray in the Sopwith Pup is designed for them as seen in the photos below.
BTW, this aircraft is tiny compared to my UMX planes.
Good thing the servos are far forward, as you don't want any ballast weight. The Sterling D8 I showed has the Gotek servos for the tail mounted in the front fuse keels to allow the battery to fit between, coming it at 100 grams with battery. Really have to cram everything up front on the small WW1 aircraft.

Quote:
Originally Posted by CGordon
I'd recommend direct soldering; the weight savings is decent and it is a solid connection with a custom length.

I have a couple of the linear servos but have not fitted them. They seem ok but the 1.7g rotaries are just great. I combine the +/- wires and pull the backs off (drop of glue on the motor case) for less weight. Will try litz wire at some point.
That's respectably light weight for two 5320 servos, receiver, and ESC.
Sep 22, 2019, 07:45 PM
Registered User
Crossup,
How do you pull the pins? I have a lot of 1mm connectors that have the positive and negative wires switched, and seeing that always bothers me.

Thanks
Fritz

Quote:
Originally Posted by crossup
HK also sells converstion cables, I have nearly every combo of 1mm, 1.25 and 1.5mm from them, mostly because then I can take advantage of deals where the servo/esc/rx doesnt match what I would prefer to hook up to it.

Also they sell or have sold the pieces parts to make sell the JST and an Molex micro connectors, the crimper they sell doesnt handle all three main sizes directly but its easy enough to adapt and of course one can alway just solder them and trim the parts the gets crimped inward so they fit into the plug.

And lastly some BlueArrow servos like the 303 come with adapter cables which is a nice bonus if you need something the size of the 303.

Pic is for 1.25 servo to 1.0 rx adapter cables. CAUTION, alway make sure the pin outs are the same and if not its easy to pull the pin/socket and move them into proper order
Sep 22, 2019, 09:25 PM
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crossup's Avatar
The vast majority of micro connectors use the same method to retain them, a tab that is bent to protrude at one end. The tab is on the pin and is used to let a catch on the connector shell hold it in place.

So you see the metal that is exposed with a "finger" of plastic over it? Bend the finger up with an Exacto, very small straight screw driver etc then the pin/wire will pull right out. Try to bend the finger or tab the minimum it takes to pull the pin and wire out as you need it to spring back to hold the pin in when you replace it. If this does not make sense to you, let me know and I'll take some pictures.
Sep 23, 2019, 01:19 PM
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JohnM's Avatar
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Good idea about swapping the wires to a new connector. I will check to see if they are identical.
Sep 23, 2019, 07:48 PM
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crossup's Avatar
FMHans and I were talking about swapping wires in the same connector to make the pinout correct when to something wired differently. Of course the technique is the regardless of same or new connecor
Sep 23, 2019, 09:32 PM
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AntiArf's Avatar
Quote:
Originally Posted by fmhans
Crossup,
How do you pull the pins? I have a lot of 1mm connectors that have the positive and negative wires switched, and seeing that always bothers me.

Thanks
Fritz
Bugs me too having to remember to swap the wire colors, and I like them in the correct location for Spektrum and Lemon receivers. The plastic tabs on the HK 1.0 extension lead connectors break if you look at them the wrong way, but you can sometimes carefully lift them a hair with an exacto blade, then pull out the pins and swap the leads. My solution when the locking tabs break is to carefully glue the wires in from the back of the connector with thick CA, after swapping the leads and then activate it so it doesn't flow into way into the contact area of the pins. The insulation is a harder plastic versus silicone, so it glues well and the wires don't push out when you plug in the connector.


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