Mostech SG 2100A moving intermittently

B

booji

Member
My Satellite Setup
Moteck SG-2100A Motor
1M lenson Heath Antenna
15M CT100 Co-ax
Azurewave (twinhan) AD-SP 400 Pc card
Smart Titanium quad lnb (not in use)
Cambridge 0.6dB LNB (in use)
My Location
UK
I have just installed a 2100A Motor with a Twinhan (azurewave) AD SP400 pc card (disecq 1.2 compatable). I am driving a 1M lenson heath dish on 15M of CT100 cable.

At first everything went fine then the dish stopped moving. After trying out lots of things I got it working again but it still only moves intermittently. After about a week of trying to get it working properly I have failed as the motor still only works about 30% of the time.

I have noticed that when I drive the dish manually that sometimes it moves correctly and other time it moves a short distance (a short 100ms pulse). If i keep my finger pressed for 5 seconds it will pulse again. The LED flickers orange after each time a pulse is made. I have also preformed this operation over diseqc using DVBViewer.Pro on the postioner menu and exactly the same thing happens. This can happen at any part over the dish arc. It can work fine for 10 minutes then will only pulse for 10 to 20 tries then suddely work again. When the motor works it seems to drive the dish well and wont stop untill it's position is reached, its just the initial start where I have problems.

I have measured the voltage it the motor and it drops from 13.7 to 13.3 when the motor is going. The motor and lnb seems to draw between 300 to 400mA when driven.

I have tried everything to get this going, reterminated connectors, using a shorter test co-ax cable, removing the LNB etc but without any luck.

Any ideas?
 
Is this motor a Moteck?

Try it by selecting Horizontal channels, the PC card will send out 18v. Can you borrow a receiver to test the motor?
 
Yes its a moteck, wrong spelling sry.

I tried it on the desk before installation and it worked, however being intermittent it may have worked at that time anyway. I will take the antenna off the El bracket and try see if the problem is still there. BTW where is the tensioner?



Edit: I've just tried the motor with the antenna off the bracket and no change so its not a dish load issue.
 
Before touching it, with a dish on… just try to see if the motor has any play - if a little, it should be OK… if non with a heavy dish on it, it might be too tight.

The tensioner is a small black round ended block on the same side as the f connectors & buttons on the left side.. about 6mm x 20mm with 3 cross head screws .. two hold it in place and the third screws into a soft alloy wedge - as you tighten it, it pulls the wedge down inside, pushing the gears closer thus taking the slack (crude but it works) ... but too tight can cause excessive strain on the motor and exceed the designed 350mA diseqc 1.2 motor draw on the stb so it can't be too tight. Can't remember which screw of the 2 together of the 3, … there is a demo around here somewhere on this forum.

that's not to say it's that.. just easy to check and fix if it is.
 
After remeasuring the current at the LNB it looks like it was drawing too much power and the pc card was activataing the short circuit protection. I have a titanium 4 port lnb and it look like the 220mA it needs is too much. I've replaced it with my old cambridge 0.4db lnb and so far it works, fingers crosses.

One thing that threw me though was that the "intermittent" fault would only occur at certain positions (even when the dish unattached). On DVBviewer when I set the step size to 5 and hit the east button it would always fail on the sixth press. Other possitons worked every time. I also found other "dead" areas.

Inermittent faults are a pain though as when things work you never know what you did to fix it.

incedently has anyone managed to drive this motor with a 2 port lnb, I was planning to get 2 cards but i won't be able to do this if the motor is flakey.
 
H-H Motors are not expensive: Might it not be an idea to purchase a "spare" or a replacement?

I appreciate that the current source may not be up to the job, but it could equally be that your particular Motor (As opposed to it being a generic SG2100 issue) isn't up to spec. for some reason. Or both.

Oddly enough, I have an SG2100 which has never stepped out of line (!) in four years and I bought a Fortec Turner (Motek clone) last year for peanuts as a spare . Subsequently I decided, for reasons now lost in history, to have the Fortec Turner drive my 1.1m Triax: At first, it too started off by doing weird and wonderful things eg Missing positions, stopping for no reason. I reset the Motor and remade all connections as robustly and securely as possible and it has behaved perfectly for a year. Of course, that really proves nothing in terms of the cause (could have been a fluke!), but it does highlight your concerns over the difficulty of properly diagnosing intermittent and/or flaky behaviour.
 
There are a couple of threads going way back on the forum discussing PC cards and their problems with powering some motor/LNB combinations.
 
booji said:
incedently has anyone managed to drive this motor with a 2 port lnb, I was planning to get 2 cards but i won't be able to do this if the motor is flakey.
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You can just bypass the motor with the second cable run, just take it directly to the LNB.

I'm not familiar with DVB cards and their software, bu there is bound to be a way round the problem of one of the cards/apps not knowing which sat is being pointed at.
 
I have thought about bypassing the lnb but there is a small problem.

If I were to power my PC card via the motor to port 1 of the lnb then attach another PC card or STB port 2 of the lnb then I would have to make sure that the voltage to port 2 is higher otherwise the current would be driven from port 1, not the disired port 2.

I'm in no hurry to sort it out now the I have a working system but I think I will revisit this again in warmer weather :).
 
booji said:
If I were to power my PC card via the motor to port 1 of the lnb then attach another PC card or STB port 2 of the lnb then I would have to make sure that the voltage to port 2 is higher otherwise the current would be driven from port 1, not the disired port 2.
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:confused: You've lost me.
Surely as long as the coax thats wired through the motor has sufficient power, it will drive the motor and power the LNB.
 
Sry about the confusion. The reason why my motor is intermittent is because the 4 port LNB sinks 220mA. When the motor is running it needs annother 250 to 300mA. This is too much current for my card so it opperates the sort circuit protection and stops the voltage altogether.


If I wanted to attach another receiver then I would have a system where one receiver is attached diectly to the lnb and one is attached via the motor. Even though the LNB has 2 connections to it it only gets its power (it only draws current) from one connection, the connection with the highest voltage. So to ensure my system to work I would have to make sure the LNB with the direct connection is the one supplyling the current to the LNB, and this will only happen if the voltage ie 18V is highter than the supply from the motor say, 17.9V if its the other way around then the receiver directly connected to the LNB will drive 0mA whilst the PC card will drive 220mA + 250-300A.


mmmm this sounds more complicated now.


Alternatively I could always connect a dedicated power supply to one of the ports, set it to 20V. I would then have 3 ports spare each requiring no power to drive the LNB.

this is probably the least complicated solution.
 
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