Weird kind of H-H motor failure.

[ayelvington]

My H-H motor suddenly quit moving. (So sad) I went outside with my STAB hand-held controller and tried to see what was going on.

I pressed GOTO 0 and the dish traveled east to zero. I pressed the west button and the dish went west. I pressed the east button and the dish did nothing. I pressed GOTO 0 again and the dish traveled east to zero.

Any ideas? We're having something of an ice/snow event, so I'm trying to come up with a plan before I venture out to take it inside for work. Obviously the motor works fine in both directions. It answers some commands, but won't travel east.

Before you ask: No, I don't know the make and model of the H-H since it's "mature". I think that it's an SG2100, but I wouldn't bet on it. The original label on the top has worn off, but I'm attaching a photo of the bottom to see if it looks familiar to anyone.

 

[Titanium]

Agree that it is a SG2100, GS120, SG90 or other similar motor. As it seems the motor is mechanically working and moving east and west, I would check a few things:

1. Is the same voltage supplied to the east and west function or is one direction being triggered with Horizontal 18Vdc and the other direction triggered with Vertical 13Vdc?

2. If providing Horizontal 18Vdc from the STB, does the motor drive both East and West using the manual drive button on the bottom of the motor?

3. Have you reset the motor with the motor parked at "0" using a paper clip in the reset hole next to the LED?

4. Has a East software limit been accidental saved?

 

[ayelvington]

Agree that it is a SG2100, GS120, SG90 or other similar motor. As it seems the motor is mechanically working and moving east and west, I would check a few things:

1. Is the same voltage supplied to the east and west function or is one direction being triggered with Horizontal 18Vdc and the other direction triggered with Vertical 13Vdc?

I use an independent power supply when I test the motor, so the voltage is the same and constant.

2. If providing Horizontal 18Vdc from the STB, does the motor drive both East and West using the manual drive button on the bottom of the motor?

The weather was foul enough that I didn't hang around to try the buttons, but I will try tomorrow if the weather clears up some. Good pointer!

3. Have you reset the motor with the motor parked at "0" using a paper clip in the reset hole next to the LED?

Great idea! I'll try that too when I can get to the antenna.

4. Has a East software limit been accidental saved?

That's something that I can check tonight

Many thanks for the great pointers. I really don't have the $$ to be buying a new H-H right now. I got it parked on NHK so I have something to watch on Ku for the time being.

 

[ayelvington]

Well, I sent the dish east to 0 (zero) from the receiver without any trouble. And I was able to scan/view birds as I moved west. But no joy driving the dish to the east from the receiver. I'll try the buttons in the morning, and put the motor, weather permitting.

 

[jorgek]

Basic question, have you checked your LONG and LAT settings in the receiver? Are you using USALS?

 

[ayelvington]

Basic question, have you checked your LONG and LAT settings in the receiver? Are you using USALS?

Fair question! Yes, I'm using USALS, and yes, the LAT and LON are in correctly. The birds west of zero all line up well.

 

[ayelvington]

Heavy snow for now, but I did get a chance to try the two motor control buttons. They both work. I suspect that a decoder chip in the housing has failed. I've worked on more sophisticated electronics over the years, but I'm going to sit on this until spring. I'll "shotgun" the board (in the absence of a block diagram or schematics) and that will likely put it right.

 

[Titanium]

Never have had a motor logic fail in this way. I would drive the motor to the zero position and reset.

 

[ayelvington]

Never have had a motor logic fail in this way. I would drive the motor to the zero position and reset.

That raises a small problem: Where is the RESET button? I went out, sent it to zero, and went looking for the button. I used a nylon stick through the four vent holes to no avail. Pressing the EAST button made the LED go red. (I sent it west w/o a problem, and it goes east w/o difficult using the ZERO command).

Totally the wrong kind of weather to be messing with this, and a very unpleasant development since I have no time for TV in the summer

Please look at the photos that I've posted and tell me if I've overlooked a RESET button staring me in the face.

Thanks,

Al

 

[Titanium]

Maybe I misunderstood your previous testing, but I understood that the motor east and west manual buttons would drive the motor. If pressing the east button on the motor gives you a red color error LED, that's an indication that there is a problem in the motor.

Pressing the reset button on the motor may correct that problem. The reset button is a small hole immediately to the right of the East button (LED). The diagram on the motor shows the reset button position. Yep, it's staring right at you! LOL

 

[bigg t]

One of mine " an SG2100" looks similar to that one. I believe on it you hold both the east and west buttons at the same time and have someone apply power to it while you hold the buttons in.

 

[KE4EST]

One of mine " an SG2100" looks similar to that one. I believe on it you hold both the east and west buttons at the same time and have someone apply power to it while you hold the buttons in.

Yes, a couple of mine I have are the same way, no reset button. You have to turn off power to it and hold the two buttons in and reapply power till you get 4 or 5 flashes and it is reset.

 

[Titanium]

Look at the photo in the first post. A diagram on the base of the motor housing definitely shows a reset button. You can see the reset hole on the right edge of the clear silicon LED.

 

[ayelvington]

Look at the photo in the first post. A diagram on the base of the motor housing definitely shows a reset button. You can see the reset hole on the right edge of the clear silicon LED.

Actually, that's the LED. I could see it go red as soon as I pushed the EAST button.

Tomorrow I'll try to do the push-both-buttons-at-the-same-time trick while applying power. I have a plan on how to do it myself

 

[Titanium]

There isn't a little hole partly hidden under the outside edge of the LED cover? From the photo it looked exactly like the model with the separate reset switch partly hidden by the LED cover.

Edit: yep, it is a two button reset. That fooled me!

 

[bigg t]

I actually had mine apart not long ago to work on too much play. I couldn't get it to adjust no matter what I did. It turns out that the grease they used inside had gotten on the set screws and had set like glue. I've had crazy glue that didn't work that good. Once I took care of that and reset everything it has been working great moving around a 1 meter dish.

 

[ayelvington]

Sent it to zero and tried the two-button-reset trick: no joy.
Disconnected power, pressed both buttons, reconnected power: no joy.

After much kneeling in snow and freezing my paws off, it's not getting any more of my attention for now. And now is not the season to take it off the pole and bench test it. I'm stuck with NHK for the rest of the winter for Ku band (not a bad deal really).

Poopers

 

[ayelvington]

We had a break in the weather, and I was able to store the dish in the barn while the motor is on the bench. It appears to be an electromechanical failure of the limit switch.

All of the parts move freely without binding or play, and no sign of wear on the nylon rotor gear. The worm gear back-lash adjust was properly set.

I pulled the worm-gear assembly to access the limit switches and played with their operation to see how the controller responded. I deduced that the inner switch is dedicated to the return-to-zero function. The outer switch is the travel limit switch.

There must be some sort of rules built into the controller that ignore the limit travel when returning to zero. Also, some sort of count so that it knows which direction to travel to get to zero. I don't much care for rules, so I'm not going to dwell on them. What I do need to do next is determine if the travel limit switch is normally open or normally closed. I'll pull the connector from the motor board and do some continuity testing.

I'll be saving a few bucks if all it takes is a remove/replace of the switch. It's winter, I'm retired, I got skills, what the heck!

More as I learn it.

P.S. No, there is no dedicated reset button on this motor I'll try the power-on/button-press method after the limit switch issue is resolved.

 

[ayelvington]

Well, that didn't work. I got down to the limit switches, opened them, burnished the contacts (I have a tool for that), and put it all back together.

The switches are fragile, so I ended up using a hemostat and squinting a lot to work with them.



What I know so far:

1. Both the limit switch and zero switch are working properly. (I was able to drive motor in one direction until the limit switch stopped the travel.)
2. The motor driver circuit works in both directions since I can manually drive motor one way, and it will return travel the opposite direction to return to zero.
3. The machine "hears" commands, so the demod block is working.

This has become an academic challenge now since it's really starting to annoy me.

The manufacturer attempted to obscure the labels on the IC packages, but they were cheap in that regard too.


I also noticed that two of the ICs are in sockets, and that leads me to believe that they are a)high failure rate parts, or b) frequently updated for whatever reason. The sockets cost money, so it wasn't a mistake.

I'm going to try and cross reference the two ICs in sockets to determine their function, and possibly shotgun replace them.

More later...

 

[ayelvington]

After sleeping on it, I deduced one "rule" regarding the return-to-zero function. The casting steps from high to low at the zero point. The switch opens or closes at that step point. The motor knows the direction to travel based on the state of the switch, and the motor stops travel precisely when the switch changes state. Pretty simple after a good night of sleep.