Switch harness quality
 

I am talking about the switch harness with three cables attached... one for the receiver, one for the battery and one for charging.

I don't know why, but I decided to look inside the switch cover on a brand new switch harness that I was about to install on my just-finished Ultra Sport 60. I won't say what brand it is, but it is a very common name that we all know. The soldering at the switch terminals is poor. It looks like the wires are just tack soldered to the terminals and the solder joints are cold. And there are spikes of solder coming off the joints. It looks like the work quality I did when I was 13 years old and soldering my first Heathkit.

So... this switch harness is going in the trash, not on my airplane. Don't assume that just because you buy a well know brand name you are getting quality.

As with all mass produced items, there will always be the odd one sneak through for what ever reason.
The problem with using other brand and after market brands is that whilst he housing & plug appear to fit,
the pins and sockets may well differ in size, refer to details in mid section and photo attached thereto:

. After Market Accessories - Caution re Opti-kill, Duralite, Powerbox, Switches, Leads etc.
quote:
Receiver Pins, Leads and connections.
Caution is recommended when changing Transceivers or Receivers in a model which has been used
with a different brand previously installed or a servo moved from one model to another.
The pins in different brand receivers are not all the same size, nor are the male fittings within
different brand servo plugs/extension leads all the same size.
Especially noticeable if changing from Futaba to Hitec & JR, the metal sockets in the male plugs
often stay expanded and cause intermittant problems.
Many cheap "after market" leads & plugs have different size connections
and whilst the covers may be a tight fit, the actual metal contacts may not be, with some shown to widen out
and not return to a tight fit when reused. Be alert to pin sockets backing out of battery & extension lead plugs,
a frequent unseen cause of intermittant connections and Digital Servo Burnout. (also jpg attached)


Alan T.
Alan's Hobby, Model & RC FAQ Web Links

I've pointed out the switch and connectors quality issue a number of times but for the most part, people don't seem to care very much. And heaven forbid if you should happen to say something bad about someones favorite brand. Most major companies have some good quality switches and some .... well .... not so good ones. Some aftermarket brands are just simply junk, though some of the aftermarket ones are quite good. If a person can open and inspect these items and knows what he is looking for, he is ahead of the game.

I cringe when I see what some people use for switches in some extremely expensive airplanes. But, its their airplane.

What I have learned about switches:

1. Always replace switches when you replace your batteries.
2. Price does not always determine quality. (I preferred the construction of the Spektrum switch to the others and I suspect that the Spektrum was the cheapest)
3. If you do charge through the switch, do not charge at more than 1 or 2 amps. I would be a little concerned about heat generation.
4. Disassemble any switch that you remove for replacement and analyze its guts. It'll help you make better decisions.

I think if we know a product may not be up to snuff we should let it be known so people can be aware and check theirs if they happen to have the same thing.
Also many of these switches can be sold under different brand names but made at the same factory.

What I have learned about switches:
- the darn things fail
- if you only have one, when it fails the plane dies
- use two switches and two batteries and never lose a plane due to a bad switch again

http://hangtimes.com/parallel_packs.html

I do have some models that I install dual batteries and switches but in twenty years in the hobby I can't recall having a switch fail. Yes I know anything can fail and it;s a good
idea to check things and replace if in doubt.

I did have one switch failure in the 25 years I've been in the hobby. Fortunately it was an intermittent open circuit in the negative solder joint in the switch and luckily I was able to land despite some scarey glitches. The wires on this brand of HD 3 wire switch harnesses (with built in charge jack) are just tack soldered to the back of the board very sloppily. I've since switched to the Electrodynamics switches, much better in my opinion than the ones sold by a company with 3 letters in their name:o

Pete

You could also do what a former club mate did and that was to just twist two bare wires together to make a connection . Needless to say he has been through more clubs than most of us have had hot dinners . Pretty funny if it wasnt so serious . Still pretty funny !! cheers the pope

+1 for the Electrodynamics switch. The only one I use.

Thanks everyone for all the comments and information. From now on I plan to inspect every new switch I purchase.

Even the good looking ones may not be sufficient. I always test mine with a 4 amp load (max current of servo connector). If they have a voltage/current drop I throw them away.

+2 on Electrodynamics switch. I found out about these when I replied to a similar question on this forum.

I've been modeling for over 40 years and have traced many suspected radio problems and glitches to poor connections or high resistance in switches. Years ago the high end radio manufacturers used "Noble" switches which were very high quality gold plated dual pole units. The problem was that they were big, heavy and expensive. Now we have the finest switches money can buy...... FROM CHINA.

I have also disassembled several modern switches and have been stunned by the poor quality and even worse solder joints.

Here is my solution plagiarized from an old RCM magazine. The basic part is a Deans charge connector part number 1009. Very reliable, light weight, easy to determine switch position, cheap, re-usable and repairable.

I had a brand new hvy dty Hitec switch fail on the 3rd flight. Poor solder joint. It cost me a 30% Extra and a lot of anguish. The Hitec rep's reply was, "sorry,I always use JR switches on planes I really care about." Just because its big and "heavy duty" does not mean its of good quality. I use only Badger switches now.

I also had a "heavy duty" switch fail in flight on my giant scale P-40. However, I just completed the flight and landed with no problem since I always use two batteries and two switches in parallel.

Badger switches can't fail?

The switch I trust the most is the old Noble 4F switch which went out of production years ago and my own soldering. On most new installations I use shorting plugs of known good quality. A 4 Pin Deans gives redundant contacts and good current capability.

Switches and slide switches in general - - -
Different contact metals are used for different voltages and currents.
The low voltages used to power RX's and servos call for a low voltage switch, not on intended for use
at say 120v.

The higher voltage switches often use contact materials that are designed to reduce pitting, etc. when closed
using the higher voltages. They can oxidize when used at voltages that do not keep them clean.

Low voltage switches tend to use contacts that are made of softer material, don't oxidize as easily, and can be damaged
if used with higher voltages.

Classically, the low voltage contact was gold plated, and the high voltage contact might have used a silver cad oxide contact.
Since Cadmium has a poor reputation, I'm reasonably sure that it's not commonly used these days. Not sure what replaced it.

A friend gave me a box of his old 27 and 72 mhz radio gear this weekend. Nothing in there was worth a darn....except for the one Noble switch I found!

DeoxIT sold by Caig Laboratories can be used to keep electrical contacts in top shape. Even gold plated contacts suffer from dendrite corrosion over time and can cause intermittent contact at low voltages. I used DeoxIT for many years on biomedical equipment. I brought many switches "back from the dead" many times by washing them out with DeoxIT D5 and used the 100% stuff for really tough cases. This is PROFESSIONAL grade electronic chemicals and expect to pay $20 for a little 2-oz. spray can, but it comes in bottles with brush applicators or needle tubes applicators. There are several types for several purposes and I keep 3 or 4 types around at all times. About $100 for a basic setup of DeoxIT chemicals is a bit much for some folks, but it's better stuff than gonzo audiophiles pay for their salon brand audio cable connector cleaners that don't work as well. You might be surprised how much gunk you get off your gold plated audiophiles cables and binding posts when you use Caig Laboratories DeoxIt and PreservIT. Using the Preservit after using the DeoxIT will cut way down on what you get off your contacts the next cleaning cycle. I used the rest, and Caig Laboratories makes the best. I've never seen the stuff in Hobby Shops. Go to places where professional high end electronic guys buy their stuff, or straight from Caig where you can get economical little kits for occasional users. The big cans are a better value for heavy users, but Radio Shack used to sell a little pen applicator with a felt tip that I found useless for a lot of applications. I fixed electronic and electrical problems for a living in biomedical gear.

Unknown to some people, a contact that is "working" but arcing at RF frequency can be a source of RF interference. I fixed my TV antenna booster that said "power on" but would not boost the TV signal, instead degrading it. A shot of DeoxIT to the power switch got rid of the RF arcing and fixed the component. Most people would have scratched their head and thrown away the antenna booster, thinking the amp had died. It would be a good idea to treat ALL your contacts and switches on RF frequency gear with this stuff. Your power LED's will glow OK because they cannot respond to RF and your eyes cannot detect it if the LED's responded anyway, just like 60-cycle scan rates of TV sets are "invisible" and appear flicker free. In the case of my antenna booster, the tiny amount of RF switch arcing was overriding the even smaller amount of RF signal being received. The same thing can happen to your RC receiver as servos draw current from bad contacts.

I have used Cramolin for about 45 years sold also by Caig Laboraties with outstanding results. We used in first on servo pots if the servo became jittery from residue. Also used it on all kinds of switch contact.

I found this article on the web today.
http://www.pitt.edu/~szekeres/cleaner.htm

SidGates