Echostar AD3000IP

C

Cager

Member
My Satellite Setup
Echostar AD300IP+Pace MSS508IP Various Linux and M-S computers
My Location
Norfolk UK
Hi All
I have an Echostar AD3000IP which was working fine untill a couple of months ago. It suffered a power supply fault which I have fixed but it now seems to be looking for the wrong transponder frequencies. I suspect that the 22Khz band switching signal is not getting to the LNB, although if I look with an oscilloscope at Q910 on the main board the 10Khz signal appears briefly after switching on. I cannot see this signal on the i/p coax socket under these conditions. Any Ideas anyone. I have two other good AD3000IP recievers which both work with my dish/LNB so the problem must be local!
I have restored this faulty box to its shipping condition and tried doing a search on ASTRA1 and the only transponder that is found is 10778 on which there appears to be one clear channel with advertising for "Taquilla".

I also have fourth AD3000IP which I bought as faulty for its power supply and possible parts. This one produces all sorts of odd messages with some screens having a mix of Arabic, Russian and Latin script. I did get it to do a search some months ago so at least the reciever is working. I will try updating the operating system to version 1100 and then downloading a copy of the memory of one of my good machines but I suspect tthat the problems are deeper than that.

In case anyone wonders why I am still using thes old recievers my movable dish is driven by an old 36v positioner which is not supported by more recent ones. Also I'm a cheapskate!

Cheers Cager
 
Nothing wrong with keeping old receivers going if they are still operational. My beloved old 3000 is still wired up, although its almost exclusively used for the documentaries on NHK Japan for an hour or so when we get back from work in the evenings.

Llew is the 3000 electronics expert - I'll pm him and ask hime to take a look.
 
Hi Telstar. Yes I remember Llew from some years back on this forum. I sem to remember that he was investigating the 22Khz routing but I don't know how far he got. I do now have some official schematics for the power supply that could have saved him some grief tracing them out!
 
Hi Cager

We got the official power supply schematics eventually, they're somewhere in the Echostar Schematics sticky.

Looking at my dog-eared notes,I did do a trace of the 22kHz, at least what I reckon is the path from the uProcessor. From what I can make out, it connects to the collector of Q903 (joint H/V and LNB on/off transistor) via R14/R15, D902, R16/R17, D917, Q910 (where you're checking) and R919.

Is your box switching H and V to the LNB ok? If Q903 is dead, it'll kill the 22kHz at the collector.
 
HI Llew. Nice to hear from you again and thanks for the Info. Looking at the LNB IN connector on a good unit I can see what appears to be a 22kHz squarewave superimposed on a much lower frequency squarewave. On the bad unit neither of these signals is present. I tried yesterday reloading the box software, doing a system reset and then re-scanning ASTRA1. It picks up some signals but significantly it only seems to see some Vertical channels and no Horizontal so it looks as if I will have to dig a bit deeper. By the way, in case you haven't already found them, you might be interested in Fairchild Application Notes AN4104 and AN4105 which discuss switch mode power supplies of the type used in this and probably other recievers. It's fairly heavy reading but may be useful.They are still available via a Google search.
Cheers for now, I will report further when I have time to dig deeper!!!

Cager
 
Yes, those Notes are very good for a good understanding of SMPS technology. You can find online the Power Switch used in the Echostar by searching for FS7M0880. The circuits shown in the Notes are necessarily only typical, but if I remember the Echostar's arrangement is near enough similar apart from some of the C and R values.

You mentioned that you are getting odd scripting in the Menus of one of your boxes - that's usually a sign of an eeprom memory failure. Another problem with some of the eeproms used is failure of a sector of memory, which shows up as a continual circling of dashes on the LED display when trying to reboot the receiver. I've had that one, and during the attempt to reflash the receiver, it just stops when it comes to the bad sector. Result - a box fit only for spares.
 
Hi LLew. Sorry for the delay. The Power company turned the power off last Saturday so that they could prune some trees. Power was off for about seven hours during which we were running on diesel power! The switching transients caused my Firewall computer (Old Gateway P2-266) to die and I have only just got round to fixing its corrupted hard drive. In the meantime I have tried replacing Q903 but still no joy. I have now got a bit more scientific and hung my scope and Avo onto the "LNB in" port with the LNB cable disconnected. While watching the info. pages on a TV and switching desired transponders with the remote I found that the 14/18V(H/V) switching was working correctly as I changed transpoders. Also the 22Khz( High/Low) 0.6v squarewave was appearing for transponders above about 11.720 as it should.
With the LNB cable reconnected the box will rece Lowband Vertical tranponders but no Highband or Horizontal ones. As the dish/LNB work ok with two other units the only thought that comes to mind is that the LNB is loading whatever is driving the cable. Bearing in mind that according to the backplate 400mA should be available I will try loading it with about 100 ohms and see what happens. If this is the problem I then have to identify the driving device. Q901 looks a likely candidate as a 2SA1273 is rated for Icmax=2A and Veco=30V. and it is in the right general area.

Cheers for now Cager

I am not too bothered about the box with the weird display since I only bought it for its power supply. I tried updating to the latest 1100 software but it failed to take it.
 
Odd one that. Q901 caters for analogue H/V switching only, so 1t shouldn't help changing that. Power for the LNB is provided by regulator U901, the digital switch is Q903 - it only has to turn on or off via Q904. This appears to be happening satisfactorily without the LNB load.

So - U901 may not be providing 18V with Q903 switched on with the LNB connected. It's a +12V regulator that "floats" above ground level to +18V due to the +6V pinned to its ground terminal via Q909, but works ok with +1V (12V +1V = 13v for V switching) from Q909.

Could be Q909 I suppose; it switches the +6V or +1V supply to U901 depending on the correct H/V switching from the uProcessor at its base.
 
Cager, I've moved this topic to the more appropriate Tech Head section (Work Bench and Soldering Station - the home for various Echostar AD3000ip problems).
 
Hi LLew. Last Night I had another look at the problem. I tried loading the "LNB In socket" with a 120 ohm resistor while monitoring with a voltmeter. To my surprise applying the load dropped the output volts from about 18 to about 12! I didn't check to see what happened to the 22Khz but this explains why the system couldn't find the horizontal transponders. I made a guess that the 21V supply was a likely source of this power and found that this was also dropping when the load was applied. I then pinched the power supply from my good spare and to my relief all was well. I buttoned up this combination and put the supposedly bad power supply into the previously good box. To my amazement it worked perfectly with no significant change at the LNB skt when loaded with the resistor. Subsequent testing of the box showed that it too was still able to receive all the appropriate transponders.

I don't understand what was going on but I now have three working units. It does show that checking the outputs of the power supply should be done with a dummy load in place of the LNB cable if the cable is not connected.

Many thanks for your support and comments which I have added to my paper files on this receiver

Cheers and Happy Christmas Cager
 
Excellent news that another venerable old 3000 has been repaired. :)
 
Yes, they're well worth keeping going if you don't want to 'go DiSEqC / VBox ' to drive a motorised dish.

@Cager

Good to hear you have a result. Having a spare box to play with does make things a little easier.

It's possible that the +21V from your original power supply is borderline, but sufficient to power the U901 regulator and subsequent LNB supply of the box you have it in now, owing to the overall better general efficiency of the respective components in that network compared to the 'faulty' box.

An ESR meter check of the electrolytics smoothing the 21V supply (C16 and C17) might show them as 'on the way out' - it would be a good idea to replace them if you have any problems in the future similar to the one you had.

Merry Xmas to you too, regards Llew.
 
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