Heatermeter & Adapt-a-Damper: All ok but Servo is not working


 

Leonardo

New member
Hi guys,
just landed here, my first post.
I've just assembled the HM using raspberry 3b+ with adapt-a-damper.
Everything seems ok except the servo SG90

I connect it with RJ45 cable cat 5E, with a following B schema so:
pin 3 (white-green) -> servo pwr 5v (red on SG90)
pin 4 (blue) -> gnd (brown on SG90 - black on fan)
pin 5 (blue-white) -> fan pwr 12v (red on fan)
pin 6 (green) -> servo signal (yellow on SG90)

I've tested with manual setting moving from 0% to 100% with all default settings in config GUI (1000us to 2000us) fully open at 100%; fan works perfectly. Servo seems dead.

To test better I've cut the other plug to test contacts and connected all with a breadboard.

If i touch with fingers the contact of yellow cable (keeping 5v and gnd connected) on SG90 it moves randomly.
I've checked with another SG90 and I have same behavior.
With a tester with servo disconnected I have both, on board and on the other size of eth cable, these values
4,96v on 5v-gnd
4,96v on signal-gnd

If I connect the Servo I have:
4,96v on 5v-gnd
4,63v on signal-gnd

Strange thing is that few days ago, connecting fan and servo through the breadboard it worked for a while ONLY ONCE!!!
Moving from 0% to 100% in manual mode fan increase and decrease speed and servo moves back an forth.
Then I disconnected to mount it to the Adapt-a-damper and got dead again.
After days of failed tests I read in other posts today here that some solved similar issues adding a capacitor of 47uf... I have not that here, but I tried with 100uf...Strange again...It worked only once another time then dead again!

Current status is: fan always ok, temperature detection perfect, network perfect, display perfect...I've got only that issue about the servo.

Another bit: even the two times it worked even when not moving it makes a noise like a crackle, like it tries to move but can't for some reason... (both SG90)
I also tested with a simple back and forth program on Arduino and both servo were working perfectly (no noise in that case)

I have no idea what else I could check.
Any help would be appreciated

I can provide any other info

Thanks in advance
Leonardo
 
I'd give another power supply a shot. Seems like you have proved the servos are ok with the simple back and forth Arduino program.
 
Hi Jeff, thanks for suggestion.
I've purchased a new power supply 12V 1A
Very strange behavior: at very first start up it worked. I switched off to unscrew the piece from adapt-a-damper to align it when fully open.
Switched on and it's dead again.

Actually it moves if i touch the contact on signal wire, but it seems random movements.
And it have a jump when i plug or unplug

At the plug (open) I have
4.61v signal-gnd
4.94v 5v-gnd
These are constant so i assume connections are ok (tested also several cables) more over because fan is working perfectly, increasing and decreasing from 100% to 0% (stopped)

At this point I have no idea of what else to try :(
 
Sounds to me like it could be a bad intermittent connection, or worst case, a bad servo. Check your connections into the LAN plug.
 
another thing that can cause intermittent issues with the servo is if you tightened the screw holding the damper wheel to the servo body. if you did and tightened it too much, then the damper disk could bind and not move smoothly unless you move it by hand, then the disk will move the the commanded position.
 
I'm posting a video...easier...
Initially it's dead, then I move a little signal wire, and it has some random movements.

At the end it worked for a while...after the end of the video, after 2 minutes, without touching anything else than control buttons moving from 0% to 100% it's dead again

 
Tested also with 2A power supply.
Still not working.

I’ve read signal is a 3.3v line, but I have same tension of 5v line (4.95v) when unplugged and little less (4.65v) when servo is plugged... there may be a short around soldered eth plug or somewhere around there?

These tensions are ok?
 
if it worked when you move the signal wire, you have a break somewhere in that wire or a bad solder joint there.
 
Hi Dave,
I've actually checked two (or more) pieces of everything:
- 2 servo
- several eth cables
- 2 eth plug adapt-a-damper side
- 0,5A, 1A and 2A power supply

I've also checked in the board for all pins that seemed to have "air" in the holes and soldered again

Only thing I haven't substitute is the eth plug soldered on HM, but with the tester I see tension is present and constant even when servo is dead (99% of time).
4.97v on 5v-gnd and 4.63 on signal-gnd
And these values are the same even on the HM pins behind the plug even on the other side touching open contacts on servo wires.

Last possibility...I'm using a raspberry PI 3 Model B+
I've been reading that version consume more power than previous tested ones, and it is working also a not stable software version, (I'm with the snapshot package now)...

So I'm getting a Rasp 3 (not plus) and see what happen with that (I'll have it on friday)... unless other ideas from you guys...that's my very last one :p
Thanks you all anyway :)
 
The voltage is WAY high for signal on servo -- that's your problem. See this thread: https://tvwbb.com/showthread.php?59783-Servo-Testing

Check the Ethernet jack pins on the board with a multimeter and check the solder joints with a magnifying glass. I know that is a tight area so don't be afraid to re-heat the joints with a tinned tip and let the heat (and flux) work its magic. Report back.

And, yes, get rid of the RPi 3B+ -- just get yourself a $14 Zero W from Adafruit and you'll thank me later. A week of torture testing and my HM is running like a champ with the Zero. You run the risk of the Wifi crapping out on the 2B and earlier, so just know that if you go with an older Pi, you are trading lower power consumption for lower module stability, IMO.
 
Hi Todd,
thanks for helping.
I've unsoldered the RJ45 plug from HM board, and tested again pointing tester on holes in the board.
I still have same voltage in signal-gnd and 5v-ground (4.97v).
So issue is before, but I'm not able to identify it...checking all pins I seem there are no bad contacts.
I have no idea where servo pin takes 5v
 
Hi All,
another day of testing...
after had unsoldered the RJ45 plug I put multimeter directly into holes in the board, and if I put red in 5V and black in SERVO holes, I see a contact. Is that normal?

If servo line should be 0,xV and i have same value of 5V, my idea is that somewhere 5v gets into servo channel... but I'm not so skilled to understand where and I don't know exactly the circuit.
All solderings seem ok...
Getting crazy...
 
Hi All,
another day of testing...
after had unsoldered the RJ45 plug I put multimeter directly into holes in the board, and if I put red in 5V and black in SERVO holes, I see a contact. Is that normal?

If servo line should be 0,xV and i have same value of 5V, my idea is that somewhere 5v gets into servo channel... but I'm not so skilled to understand where and I don't know exactly the circuit.
All solderings seem ok...
Getting crazy...

The 5V and SERVO pads should definitely NOT show continuity. Sounds like you have issues with the BS170 transistor tied to the Signal wire or the 1K resistor tied to the 5V line.
 
Hi WBegg,
thanks a lot!
Resistor should be ok since tester gives me aroung 1k on board...but I tested them all before mounting, since I'm little color blind...and all of them were ok.

So I'm going to concentrate on mosfet (Servo one should be Q5)...I'll unsolder and test "offline"...
Hope is that and only that!
 
Hi Everyone!
Good news!!! It is working now!! It was Q5 mosfet broken.
...step by step
I've purchased a raspPI 3B not + installing stable version...and I still had the problem. Actually I had that even in manual mode without rasp connected .

Then it must had to be the circuit. Following the line from eth servo pin I reached the mosfet Q5! I've changed with another one and now it's working perfectly!!

Thank you all for your support!
 

 

Back
Top