Another ASC1 Question

[mwdxer1]

This Winter when we had storms on the Oregon Coast I moved my dish over to the East. Well, apparently the dish is too heavy for the ASC1 as when I went to move the Dish back, the weight of the Dish is too heavy, so I kept getting error messages every few clicks. I had a time to get it back to the center of the arc. The old Supra and USS Maspro I had no trouble moving the dish from one end of the arc for 35 years. Is there some way to solve this? My dish is fairly heavy 8.5 foot solid fiberglass, but I feel the unit should pull the dish back.
Thanks.

 

[Magic Static]

I think you have degradation of multiple components. A 35 year old mount on the Oregon coast will have a lot of corrosion. How old is the actuator? If the actuator was trying to pull more power than the ASC1 could provide, i would think it would pop a fuse. I've seen where they put two actuators on those heavy dishes, one on each side. One pushing and one pulling but only one sensor hooked up.

 

[Titanium]

Highly doubtful that this is a weight issue. If the dish can only be moved by tapping the East West for less than a 1/2 second, there is an error on receiving the sensor count. If the dish movement error message can be cleared by pressing OK then the dish moved again, it is a sensor count return error.

If it were an overcurrent issue, the dish would move, but self protect and shut down, requiring the ASC1 Master Power Switch to be switched off to reset or in a worst cast, pop a fuse like Magic Static suggests.

Is this the same actuator than was previously used?

Is this the same distribution wiring that was previously used?

Does the positioning count change on the front display as the dish is stepped across the arc with the >1/2 second East / West button taps?

 

[mwdxer1]

Yes, the wiring in the ground is 35 years old. I thought of that. I may try to run a separate lead from the sensor/motor wires across the ground into the house and see if there is an issue. However, when there is little weight on the unit, the dish moves fine. Moving the dish over to the East, going down, it works fine. But bringing it back up, I get the error every click or two, until I get 1/3 up towards the center and the errors go away. The errors only happen when there is a heavy pull on the dish. The pivot points do not have bearings. There is much a bolt through both the bottom and the top, but I keep when well greased. Being such an old Dish, there is play in it. However back in 1985 it was built only for C Band analog. But I got the old sows ear to work for C/KU digital. Replaced the LNBs too.
The actuator has been replaced many times. I use a Thompson Saginaw heavy duty unit. The light ones strip right out in our winds. I think I may have a spare motor too. I have replaced the arm a few years ago, but our storms have not been as strong either. But for some reason the Supra still will move the dish without errors. Strange.

 

[Titanium]

Check for common mode RFI (noise) coupling from the motor to the sensor circuit. A motor under load will emit much more noise than a motor running freely. If strong coupling, this will mask sensor pulse cycle counts.

Be sure that the sensor s1/s2 bundle has a shield only around those two wires and the shield's drain (bare) wire is only connected to the ASC1 GND terminal. The other end of the s1/s2 shield (at the motor) should not be connected (open).

If you have a scope, this RF common mode coupling will very obvious. Other ways to address this is to use a type 43 ferrite torrid and wrap the s1/s2 wires around the donut 6 -10 times before connecting to the ASC1 terminals.

Older distribution wiring may have a break, corrosion or impedance issues if water has infiltrated the cables. This will often increase coupling or decense.

Aging motors put out more RF noise as brushes age. Sometimes a capacitor across the motor leads will attenuate this RFI.

Reed switches can magnetize if parked on a magnet or as they age. One the mercury is angled differently, the switch operates more reliably. A sticking reed switch waveforms are often ragged or stutter causing logic errors.

Throwing quite a few possibilities out there. Maybe one of the above is the solution. Think your temporary sensor wiring is a good place to start if no scope is available.

 

[arlo]

Mind if I bug in? Saginaw arms have some heavy duty grease that gooks up after a few years.
You could pop yours off and pull the motor. Mark it where the bottom of the tube points towards the ground.
Before you go any further you'll want to go the the lowest sat where the arm is drawn in the most.
Pull the motor and run the screw all the way in. Count and track how many turns MINUS 3 turns.
It will help you find your lowest sat later on when its back together.
Get a few Zerks from the auto parts store. Drill a hole just-too-small in the center of the tube length (where it faces the ground) just deep enough to penetrate the tube (no shavings inside). Then thread the Zerk in with vice grips. It should self tap. Just a few turns.
I used a donor Allen wrench in the end and my DeWalt after pumping in grease to run the screw in and out. Give it a little more grease. It will squish out so be prepped for that. Run it in and out a few times with the drill. It'll move easier as the grease distributes. Run it back in all the way carefully and wind it out 3 or so turns.
That's where you'll put it back on the dish.

The motor. If you're ok with mechanical things they come apart easily. Again Saginaw grease gets gooked up.
If you're lucky the gear train will just need cleaned and greased. Again not a hard thing to do.
Getting on with the motor. Carefully take it apart and be very careful of the brushes.
One thing I've seen is one of the magnets comes unglued. The armature drags on it. Hopefully you're not in that boat. If so and you tackle this, get back to us.
Clean the armature good. Be careful with solvents. Especially around the magnet glue. Use a Scotchbrite pad to shine the commutator and shaft ends. Nothing too much. Just enough.
Clean out the bronze bushings good. Wipe in a good coat of grease. Not too much.
Clean the brush holders real good. Look for any damage or worn out brushes, all that stuff.
Put it all together. You can run the motor to it's limits with a few chunks of wire and a 12v car, Harley battery.
Set the lower limit. That's where you'll bolt the motor back on the screw tube.
Upper limit will depend on where your dish "flops". You can set that later on. It's slow but a 12V battery is handy for that. Then you can scan for your sats again. Write the locations down on paper.
If you do that and your dish pivots are greased good you've saved a couple hundred bucks minus a six-pack.
That is if the actuator isn't toast. And now you can pump a little grease in it and drive out any water.

Oh. BTW. I've never done this before.

 

[mwdxer1]

Thank you both for the great advice. A good project for this Summer. I also want double check the continuity of the wiring with an ohm meter. 35 years is a long time even though it is very heavy Ribbon Cable. Very tough. But still the age. So it looks like an ASC1 issue is probably ruled out. It is odd that the old Supra moved the Dish fine, but hooking up the the ASC1, there may be some issue in the wiring. Sensor wiring is one place I need to check too. The motor wires are probably okay as they move the dish. I think I will run wires out the door to the actuator, Sensor and motor wires. If that fixes things, I know the the wiring is the issue, if not, I'll go after the motor and the actuator itself. As I mentioned I do have a spare motor, so at least I have that to start with. I'll keep you all posted.

 

[Titanium]

I would test by only running a temporary 2 + shield between the sensor s1/s2 and ASC1. Keep the motor and servo on the current ribbon wire. No need to run temporary motor and skew distribution wires.

Good luck with your testing!

 

[Brct203]

Could it be that various elements (corrosion of the mount, old "solidified" grease in the actuator, weight of the dish) combine and result in the dish moving up from the East very slowly, so the pulses are not as frequent and the ASC-1 "loses patience" and thinks there are no pulses coming and interprets it as a limit reached situation? And that maybe the Supra is more patient then the ASC-1 with slow pulses?

 

[mwdxer1]

Thanks again. Yes, I was wondering if the ASC1 is more picky. Even if I had a new arm & motor, the weight of that NQS dish is pretty heavy. Has a solid iron frame. Only 8.5 foot, but I always have bought Thompson Saginaw actuators that would move a 12 foot dish. It is one heavy frame. It has survived the winds of 135 MPH, a tree falling across it. A mesh dish would have been destroyed several times over. No bearings, just a bolt through the pivot points. There is some slop in the dish frame always had some. But in 85 is was a analog C Band dish and in those days it did not matter. I am amazed I got it to work well on KU, but that was years ago. I mainly use it for the TV diginets now. I run it from AnkF1 to G19. The only time I move it out of the way to a low area is in the high winds so the winds do not hit the dish straight on. The wind has moved 1500 pounds on cement in the ground (Pole Mount). I should had done a HtoH Tripod mount.

 

[arlo]

If it's the "oomph" the actuator can give the dish to move it. It very well could be friction in the actuator arm.
Or the dish pivots. Lots of factors. Could be your reed/sensor isn't providing pulses fast enough to satisfy the ASC-1.
I have a heavy 12' 'glass dish. I put pillow block bearings in place of the original bolt and bushing setup.
Friction there solved. And no slop.
It originally had a 24" Saginaw actuator on it. The arm mount was about 18" from the dish center.
I've extended the mount out to around 30" from dish center and put a 36" actuator on.
Takes care of actuator stress and load.
Last I built an encoder disc with 20 pulses/revolution to replace the original 6ppr magnet.
This winter was the first my ASC-1 didn't freak out with a motor stall error.
No matter how cold and slow the actuator moved, pulses were detected soon enough.
It's all in just diagnosing the cause and fix for the stuff you're seeing.