Working With Servos

PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
26,723
2,766
Tamworth, Staffs.
Tell me about it.
Bit of a b....r being red - green colour blind isn't it!!

Except for some no longer available old AM equipment, the middle wire is always positive.
The lightest colour wire is usually the signal wire. White, Yellow & Orange.
That makes the opposite wire Negative (-).

Tony,
I have come across some servo's where the signal wire has been Blue!

But I suppose there is not Red, or Green, in Blue or Black? :(
 
Madman

Madman

Registered
25 Oct 2009
13,828
2,071
Pennsylvania, USA
doh.jpg
 
  • Wow
Reactions: 1 user
P

Paul M

Registered
25 Oct 2016
5,413
968
57
Royston
Tony,
I have come across some servo's where the signal wire has been Blue!

But I suppose there is not Red, or Green, in Blue or Black? :(
That's why you read the wiring instructions. Being in the electricity industry, I know how bored these designer chappies get. Wiring standards and colours are regularly changed for no real reason
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
26,723
2,766
Tamworth, Staffs.
That's why you read the wiring instructions. Being in the electricity industry, I know how bored these designer chappies get. Wiring standards and colours are regularly changed for no real reason

You just need a gullible-assistant....

"Here, hold this!"

BRRR-ZAP!!

"Right, so this IS the Neutral!" :devil::giggle::giggle::giggle:
 
Madman

Madman

Registered
25 Oct 2009
13,828
2,071
Pennsylvania, USA
I am at my wits end, and I didn't have many to begin with.....:swear:.....I reversed the position of the plug from the servo. I tried all three sets of connections on the tester. I checked to see that the supply voltage was between 4.8 and 6 volts DC and correctly wired to the tester. I tried several different brand new servos.....:banghead::banghead::banghead::banghead::banghead:
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
26,723
2,766
Tamworth, Staffs.
Have you tried altering the 'Select' button? - it should step through the three modes of operation, and move the illuminated LED along..

When you plug a servo onto the tester.. Do you get a small 'twitch', as the servo settles?


I have just tried it with a tester here, and even with two servo's connected in reverse, I have not damaged the tester..
Can you check you get +/- volts on the output pins?
 
P

Paul M

Registered
25 Oct 2016
5,413
968
57
Royston
You just need a gullible-assistant....

"Here, hold this!"

BRRR-ZAP!!

"Right, so this IS the Neutral!" :devil::giggle::giggle::giggle:
In July 2006, the 3 Phase wiring colours were changed from Red, Yellow, Blue and Black for Neutral. The colours are now Brown, Black, Grey and Blue for Neutral. So if you're working on an old installation, you may well find the above is not too funny. as to why the colours were changed from nice bright ones to dull dingy ones no-one has ever come up with a good solution, the theory that it complies with European standards does quite ring true.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
26,723
2,766
Tamworth, Staffs.
In July 2006, the 3 Phase wiring colours were changed from Red, Yellow, Blue and Black for Neutral. The colours are now Brown, Black, Grey and Blue for Neutral. So if you're working on an old installation, you may well find the above is not too funny. as to why the colours were changed from nice bright ones to dull dingy ones no-one has ever come up with a good solution, the theory that it complies with European standards does quite ring true.

There is anecdotal evidence that a member of the IEEE resigned over the changes, saying that "someone will be killed by this".. - I beleive this is the case, but we are unable to confirm it with the victims.

I do know of a case, of new meters being installed in a works, and when things were turned back on, the twin 13A socket outlet faceplates (which happened to have USB charging point in them) proceeded to blow themselves apart!

The installation(s) had both wiring schemes present. - I do not know the final outcome, but Blue for a phase and Black for neutral on the old scheme, and Black for a phase and Blue for a neutral , on the new would be my take on it?
I deal with a lot more colours, but a lot less potential! :nerd:
 
Madman

Madman

Registered
25 Oct 2009
13,828
2,071
Pennsylvania, USA
Have you tried altering the 'Select' button? - it should step through the three modes of operation, and move the illuminated LED along..

When you plug a servo onto the tester.. Do you get a small 'twitch', as the servo settles?


I have just tried it with a tester here, and even with two servo's connected in reverse, I have not damaged the tester..
Can you check you get +/- volts on the output pins?


I've run out of things to try. Yes, I went through the selection more times than Carter has Liver Pills or the other Carter has peanuts.
 
P

Paul M

Registered
25 Oct 2016
5,413
968
57
Royston
There is anecdotal evidence that a member of the IEEE resigned over the changes, saying that "someone will be killed by this".. - I beleive this is the case, but we are unable to confirm it with the victims.

I do know of a case, of new meters being installed in a works, and when things were turned back on, the twin 13A socket outlet faceplates (which happened to have USB charging point in them) proceeded to blow themselves apart!

The installation(s) had both wiring schemes present. - I do not know the final outcome, but Blue for a phase and Black for neutral on the old scheme, and Black for a phase and Blue for a neutral , on the new would be my take on it?
I deal with a lot more colours, but a lot less potential! :nerd:
Yes old installations have 2 codes of practice, one has blue as a phase, the other blue as a neutral. Yes f $^/#/^^$/g lethal if you don't concentrate.
Sounds like the sockets were subjected to 415 volts as opposed to 240. Either missing neutral altogether, or read the above. If it was a certified Meter Operator, they would have lost their jobs, the amount of damage caused would cost a pretty penny and all because some burka got bored
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
17,965
3,696
72
St.Neots Cambridgeshire UK
Yes old installations have 2 codes of practice, one has blue as a phase, the other blue as a neutral. Yes f $^/#/^^$/g lethal if you don't concentrate.
Sounds like the sockets were subjected to 415 volts as opposed to 240. Either missing neutral altogether, or read the above. If it was a certified Meter Operator, they would have lost their jobs, the amount of damage caused would cost a pretty penny and all because some burka got bored
Perhaps once we have finally left you inow what that cannot be mentioned we could go back to Red, Black and Green. Trouble is the do gooders would say that it was changed for the colour deficient. So do not employ them as Electricians.
 
M

Michael

Registered
26 Jan 2010
135
16
I've run out of things to try. Yes, I went through the selection more times than Carter has Liver Pills or the other Carter has peanuts.

Whilst you have tried several new servos you can still check the tester is working using an LED. Connect the negative lead of the LED (usually the shorter lead) to Gnd and the positive lead via a 220 ohm resistor to the servo output.

You should be able to detect a small variation in brightness as you move the knob fully to the left and then fully to the right.
 
Madman

Madman

Registered
25 Oct 2009
13,828
2,071
Pennsylvania, USA
Whilst you have tried several new servos you can still check the tester is working using an LED. Connect the negative lead of the LED (usually the shorter lead) to Gnd and the positive lead via a 220 ohm resistor to the servo output.

You should be able to detect a small variation in brightness as you move the knob fully to the left and then fully to the right.


I will give that a try today. Although I have two different testers. One brand new, the other I found in my stash of stuff. Must have purchased it a few years ago, but forgot I had it. One more reason less is more.....:)
 
M

Michael

Registered
26 Jan 2010
135
16
Sorry that won't work please ignore.
 
The Shed

The Shed

Registered
POS (Red) lead from Servo Tester to POS on Multi meter, SIGNAL (Orange) lead on Servo Tester to NEG on Multi meter.

Figures below based on a 5V Supply.

First Blue Led, Potentiometer range from 4.48V to 4.78V.

Second Blue Led, Centre 4.63V.

Third Blue Led, Sweep range from 4.51V to 4.74V.

Servo Tester 4.78V.png
 
Last edited:
Madman

Madman

Registered
25 Oct 2009
13,828
2,071
Pennsylvania, USA
POS (Red) lead from Servo Tester to POS on Multi meter, SIGNAL (Orange) lead on Servo Tester to NEG on Multi meter.

Figures below based on a 5V Supply.

First Blue Led, Potentiometer range from 4.48V to 4.78V.

Second Blue Led, Centre 4.63V.

Third Blue Led, Sweep range from 4.51V to 4.74V.

View attachment 269716


I performed the test using an LED, suggested by Michael. That didn't work. I'll give this method a try today.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
26,723
2,766
Tamworth, Staffs.
Dead simple test for an output:

With power on the tester, plug a servo onto the output pins.. 99 out of a hundred times, there will be a slight 'twitch' from the servo.. - This proves there are volts out, and a signal of some sort.

I have not managed to 'pop' the output transistor on a tester, but it appears you may have? :(
 
Madman

Madman

Registered
25 Oct 2009
13,828
2,071
Pennsylvania, USA
Dead simple test for an output:

With power on the tester, plug a servo onto the output pins.. 99 out of a hundred times, there will be a slight 'twitch' from the servo.. - This proves there are volts out, and a signal of some sort.

I have not managed to 'pop' the output transistor on a tester, but it appears you may have? :(

Did the meter teat and the output voltage matches the input voltage, in this case about five volts, exactly. Turning the knob on the tester doesn't change a thing.

When I plug a servo into the tester I don't get the "twitch". Both testers act the same.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
26,723
2,766
Tamworth, Staffs.
Did the meter teat and the output voltage matches the input voltage, in this case about five volts, exactly. Turning the knob on the tester doesn't change a thing.

When I plug a servo into the tester I don't get the "twitch". Both testers act the same.

Check you are measuring across the TOP pin, and the MIDDLE pin.. - The bottom two pins are supply, and would give 5V no matter what you do.

PhilP.