New HS-77BB Servos turning the wrong direction?

Hello,
About two years ago I developed a wireless servo system where a HS-77BB servo would turn 90 degrees clockwise. Everything works great and I've made probably a dozen over the past two years. Well I went to make two more today and upon receiving all my parts (same models as before, same board layout, same seller of arduinos) the new servos seem to only want to turn in counterclockwise direction.

Using the same exact code I've been using for two years with the same model parts suddenly doesn't work because of this. Both servos are doing this with both sets of boards.

Both servos were bought from ebay, from two different top rated sellers - one whom I've bought this same servo from before.

Running from two Arduino Mini Pro 5V, HS-77BB Servos, ServoTimer2, and RadioHead libraries.

Here is a video hopefully showing the situation. Both servos are running the same code, so both start at the same position code wise - YouTube

I'm quite confused.

zenixnet:
Hello,
About two years ago I developed a wireless servo system where a HS-77BB servo would turn 90 degrees clockwise. Everything works great and I've made probably a dozen over the past two years. Well I went to make two more today and upon receiving all my parts (same models as before, same board layout, same seller of arduinos) the new servos seem to only want to turn in counterclockwise direction.

Using the same exact code I've been using for two years with the same model parts suddenly doesn't work because of this. Both servos are doing this with both sets of boards.

Both servos were bought from ebay, from two different top rated sellers - one whom I've bought this same servo from before.

Running from two Arduino Mini Pro 5V, HS-77BB Servos, ServoTimer2, and RadioHead libraries.

Here is a video hopefully showing the situation. Both servos are running the same code, so both start at the same position code wise - YouTube

I'm quite confused.

Welcome to the real world of Chinese-made stuff. They may have the same part numbers stamped on them, but obviously are wired differently. Same thing occurs with relay modules. Some activate when the control is low and some activate when the control is high.

Some companies inspect every batch of components to see if they are what they were last time.

Good luck, Paul

Hobby servos never do specify which way they will turn with increasing pulse width. Maybe you have fakes or maybe Hitec have just decided to change the spec. It's mildly irritating but doesn't make much difference in most normal uses.

Steve

slipstick:
Hobby servos never do specify which way they will turn with increasing pulse width. Maybe you have fakes or maybe Hitec have just decided to change the spec. It's mildly irritating but doesn't make much difference in most normal uses.

Steve

I do see that both of the new servos have a QA passed sticker on them with a leaf symbol, whereas the original servos do not. Perhaps they were manufactured at a different facility with different standards?

However, it seems in my case it makes a difference. The way ServoTimer2 works seems to now allow me to control the servo in any other direction. The lowest number it accepts only moves the servo like 30 degrees because it thinks the servo can move the other way.

I can't see your code so I obviously don't know what you're writing to the servo but if you're saying that write(750) followed by write(2250) only moves the servo 30 degrees then it's definitely a faulty servo.

Otherwise surely you just need to modify the initial and final values you write until it moves as you want.

Steve

slipstick:
I can't see your code so I obviously don't know what you're writing to the servo but if you're saying that write(750) followed by write(2250) only moves the servo 30 degrees then it's definitely a faulty servo.

Otherwise surely you just need to modify the initial and final values you write until it moves as you want.

Steve

I'm using ServoTimer2 which accepts values from about 1000 to 2000. With the new servos 1000 sets the servo about 30 degrees (tried setting to 0-800 and the most I could get it to move was about another 10 degrees) and 2000 tries to write it in the other direction, which it can't move. With the old servos going from 1000 to 1800 is a flawless 90 degrees. I guess it's possible I got two bad servos?

You have counterfeits - the HS-77BB has a defined rotation direction.