need help slaving an S2-FTA (TBS6925) to 4DTV (DSR-922)

[two4two]

My current setup is big dish, C-Band and Ku-Band LNBs in a single feedhorn. These work(ed) on the 4DTV and still do if there are open signals. There are a few clear open digital C-Band DC-II signals on SatMex8 that work just fine, and then there are clear analog C-Band signals such as C-Span, HSN and QVC that work OK. I can't find any open Ku signals, DC-II or analog. Anyway, the LNBs are the ones that work(ed) on the 4DTV. So now I got a TBS6925 FTA MPEG S2 receiver and slaved it to the 4DTV as follows: the 4DTV is the positioner and controlls the polarity, etc. I have two hi-freq splitters that are 2-way. They have red lines from inputs to one of the outputs, and these are the sides I send to the 4DTV. I send the other sides to a 2-input DiSEQC combiner, and from there to the TBS6925. The Ku-band works OK in the TBS6925 (I set it up as LOF = 10750). I'm getting some good hits. But the TBS6925 can NOT lock any C-band signal. As I mentioned, the 4DTV can definitely lock and tune those open signals. So, what I can figure is the LNBs work OK, the co-ax is OK, and the 4DTV side of the C-Band splitter works, while the TBS6925 side of the Ku splitter works (I'm assuming the 4DTV side of the Ku splitter works too, but there's no signal available for the 4DTV to tune to verify that). So, either the TBS6925 side of the C-band splitter is bad, or the DiSEQC is bad, or the TBS6925 itself is bad in the C-band range. I got an RMA from BUYdvb online and been told to ship it back to China. I've heard horror stories of people trying to return merchandise back to China because the Chinese customs agents simply steal it. I'd like to verify that the unit is definitely bad before throwing it away into the trash heap of doing business with China.

I believe my 4DTV has a loop out connector. Would it be possible to connect that loop out to the input of the TBS6925 and thereby bypass all of the splitter/combiner stuff? How would I set up the TBS6925 to do that? This way I can can get a better idea of where the problem lies.


Also, I think I'm going to get an OpenBox X5 and see if IT can lock those C-Band signals.

 

[Magic Static]

Well without knowing what software you are using with the DVBS2 card, it's hard to say exactly, but Use the loopout and set a custom L.O.1 5150 - SW 11700 - L.O.2 10750 If the 920 will pass the 22khz tone it should work
I'm not a 4DTV person. I don't know the 920 that well. Not sure if you even need 22khz in that setup.

 

[FaT Air]

I can't find any open Ku signals, DC-II or analog

Don't think there are any.
TBS card>> diseqc port1>>Ku splitter >> 4DTV Ku in
MMMMMMMMMMM port 2>>C splitter >> 4DTV C input

Got the correct port selected? Port 1 is 'default', selected if nothing is selected.
Is the C band LNB powered (selected with the 4DTV) ? [unsure if they are on continuously or if only when selected]

 

[DRCars]

My suggestion would be to simplify to determine what may be SNAFued.

I use a 4DTV 922 as a dish positioner/polarizer. You don't even need to hook the LNBs to the 4DTV. Just use it to position the dish and change polarity/skew. For testing purposes just hook the C-band LNB straight to the TBS 6925 and let it control the power to the C-band LNB. That will give you a setup with nothing in between the TBS 6925 and the LNBs (except the cable). If you can get a C-band signal that way then you for sure know there is nothing wrong with the TBS 6925. Since the same tuner is used for C-band and Ku band, and since you say you are getting Ku channels, then there is probably nothing wrong with the tuner anyway. It doesn't care if a signal is Ku or C-band since it only needs to tune the local oscillator (LO).

If you simplify like this and still see no C-band activity you may have a problem with a cable/connector. To test that you could swap the Ku band cable to the C-band LNB.

BTW, the 4DTV does not have LNB loop thru. What you may be seeing is the TV IN/OUT.

DRCars

 

[updatelee]

You cant use a diseqc backwards, thats what it looks like your doing anyhow.

6925 -> 4DTV -> 22khz switch -> LNB

Im not sure what this Ku / C splitter is your referring too

UDL

 

[mmewrench]

The DC splitter should have one side power passing, and one side dc blocked.the power passing side should be hooked up between the 4dtv and the lnb with the lnb connected to the input side of the splitter. Connect the dc blocked side to your lnb port on the switch. In this way the 4dtv will power the lnbs and the splitter will prevent voltage from feeding back to the receiver/tuner card. This is a definite advantage since the voltage is constant regardless of the polarity, and there is enough current to power the most power hungry Pll lnbs. It sounds like maybe you have a bad switch or the wiring is wrong.

There is no loopout on the 922. One output is for Cband the other is for Ku and there is an input for an ota antenna. Both outputs are powered when the receiver is plugged in after the warmup cycle. For this reason its recommended to unplug the power cord before removing or switching coax connections.

You may have a damaged switch. I would eliminate the switch and hook the C band side directly to your tuner card to see if that works for you. As long as you can receive C band on the 4dtv you should be able to receive it on the tuner card. If removing the switch doesn't solve the problem try swapping the splitters to eliminate the possibility of a bad splitter.

If all else fails then replace your coax jumpers on the Cband side.

 

[two4two]

OK, thank you eveyone. mmewrench, I had it set up exactly as you said. So, I got 2 new switches. So, let me ask, if I hooked up the new switches backwards -- with the power-passing side on the TBS6925 -- would it ruin the TBS6925? What if I did NOT unplug the DSR-922 before replacing the splitters? I'm not as steady as I once was and I touched the conductor against the side of the post on one of the splitters and got a small spark. C-Band still works on the DSR-922: clear DC-II channels on SatMex8 work fine. But now, not only does the TBS6925 NOT tune C-Band, but it can no longer tune Ku either. However, the signal strength says 100% for both C and Ku! It never did that before for either C or Ku. Next I'll try connecting the LNB(s) directly to the TBS6925 and see if I can tune any signals on either band. I really do hate to have to return the unit because it has to go back to China, and it is known that Chinese customs simply steals anything you send back and your money just goes down the toilet.

 

[two4two]

PS: with the C-band lnb connected directly to the TBS6925, is the TBS6925 capable of controlling the polarity on the lnb? So that when Kaffiene software does a scan it will set polarity based on the tuning data file?

 

[mmewrench]

You will need to use the 4dtv to control polarity, its easily changed by switching between channel 1 and channel 2 (the 4dtv must be turned on in order to control polarity, and switch channels) on any transponder. For testing purposes I would only scan a horizontal transponder with your polarity on the feedhorn set to match. The reason for this is that your tuner outputs 18v on horizontal channels and the average lnb requires this higher voltage to work properly. Anyone feel free to correct me if Im wrong about voltage and polarity.

I don't know how sensitive the splitters are, but I know most diseqc switches would not survive the spark you described. As far as the tuner card is concerned, Updatelee could tell you more about whether or not it could be damaged, and how to test for that.

 

[FaT Air]

IIRR, I read somewhere it's illegal to bring anything capable of receiving DVB satellite signals into the country (China). So their 'customs' agents confiscate said equipment.

Can you check for 13/18 volts on the cards LNB(F) input?

Use Horiz when powering the LNB with the card. H=18v V=13v

is the TBS6925 capable of controlling the polarity on the lnb?

The 4DTV will operate the polarity servo of the feed.

 

[two4two]

You will need to use the 4dtv to control polarity, its easily changed by switching between channel 1 and channel 2 (the 4dtv must be turned on in order to control polarity, and switch channels) on any transponder. For testing purposes I would only scan a horizontal transponder with your polarity on the feedhorn set to match. The reason for this is that your tuner outputs 18v on horizontal channels and the average lnb requires this higher voltage to work properly. Anyone feel free to correct me if Im wrong about voltage and polarity.

I don't know how sensitive the splitters are, but I know most diseqc switches would not survive the spark you described. As far as the tuner card is concerned, Updatelee could tell you more about whether or not it could be damaged, and how to test for that.

If I had plugged the co-ax directly into the TBS6925 would the DSR-922 still be able to control the polarity? The DSR-922 has a few DC connections in the back: the heavier guage ones are for operating the positioner, but are the lighter guage wires the ones that would control the polarity? Or is this control signal sent through the co-ax? I ask this because I had the co-ax plugged directly into the TBS6925, in which case it wouldn't go through the co-ax to the lnb because it was not connected to the DSR-922.

In case I ruined the DiSECQ switch when I caused that spark I have a Dish SW21 that I think would do the job. One other thing, maybe updatelee knows: these DiSEQc switches are operated by 22kz tone, right? How do I get that tone from my PC to the switch? This is a Linux machine BTW. I don't see any setup software where I would specify voltage vs tone for the DiSEQc control. As far as I can see, these DiSEQc switches serve the same function as a hardware selector switch where you slide the slider back or forth to choose input A vs input B, except they aren't operated physically by your thumb and finger; they are operated electronically by your equipment, hence the acronym DiSEQc means Digital Satellite Equipment Control. It is either a voltage or a tone that causes the thing to switch from one input to another. So in this case the TBS6925 or the software (Kaffiene) should send the signal. I can't see my computer has enough voltage to send that kind of voltage signal, so I should have to choose tone burst, right? I don't see anywhere where I can specify that choice.

Well I did the tests of plugging the co-ax from the lnbs directly into the TBS6925, and for a fact, now I can tune no signal, and always the signal level is 100% (never used to be that way) and SNR is 0. This on both C and Ku band. So I ruined SOMETHING with that spark. The DSR-922 still plays the clear C-band channels on SatMex8 and such. I tried to find a backhaul feed or something in Ku so I could verify the lnb is still good. No luck yet, but when I go to a Ku satellite it shows some transponders with high signal strength and quality, but these are not NTSC or DC-II signals so they don't show a picture.

I'm going to put in my alternate DiSEQc switch and see if I can tune some signals on the TBS6925. I'm trying to figure out when I've determined the TBS6925 is no good. I figure that money is wasted because there's no way it'll go to China and actually be received by those people (BuyDVB online, TBS's distributor) and they will replace it.

 

[mmewrench]

Yes if all the wires are hooked up properly to the 4dtv (except the coax), the 4dtv will control the polarity. You will have to do it manually by switching between channel 1 and 2 with the 4dtv remote.

 

[two4two]

OK, so it looks like it's dead

With the co-ax connected directly to the TBS6925 it can lock no signal. The software (Kaffiene) says the signal strength is always 100%. This has never happened before. And it always says SNR = 0. So it looks like it is dead. Time to pull it and pack it up and send it back to BuyDVB, as TBS said to do, and give up on ever getting a replacement because I know Chinese customs agents will steal it. I sent an e-mail to TBS asking if there was a place in the USA that could honor the warranty. I'm waiting for that reply. That's my last hope.

If, in fact, I send it to China and never hear from them, I'm going to post on the TBS forum warning about the situation.


Now, I saw another brand of manufacturer that uses the same chipset. It has a SAA7160 and an STV090x. I don't know which chip does what. But I remember seeing another card that boasted the same specs as the TBS6925 and so the cards would be identicle except in name. Anyone know which card that is?

 

[updatelee]

There are lots of cards that use that chipset, some the same cut (0x30) others (0x20) some the BAC others the BAB demod.

UDL

 

[two4two]

There are lots of cards that use that chipset, some the same cut (0x30) others (0x20) some the BAC others the BAB demod.

UDL

It is the NetUP Dual DVB-S2-CI card. It boasts the same capabilities as the TBS6925, but I don't know anything about it. Thye don't list a price; they have a link for you to request a price. I did that but never got a response. (Actually, I didn't check my Spam folder in my e-mail account, so it might be there.) Anyone know anything about this card?

 

[updatelee]

There are two cards that use the same demod as the 6925 (many more that use slight variations of it)

NetUp and the Omicron advanced. Bother are very very expensive, 2-4x the price of the TBS6925.

Do you need ACM/VCM demod? if you dont there are much cheaper cards out there. The skystar 2 express HD is around $80 shipped, uses the same demod, same cut, minus the fact its only the consumer model vs advanced model. It will lock ACM/VCM under specific cases, but not all like the advanced will. Its my goto card, very fast. Great price.

UDL

 

[two4two]

Any comments on OpenBox x5 STB? It has component out for older systems.

 

[updatelee]

nope, no clue. Havent touched a STB in years. I use PC tuners in Linux exclusively.

UDL

 

[two4two]

Anyone have any experience with having to return a TBS6925?

 

[two4two]

PS: now, in /dev/dvb/adapter0 there are only net0, demux0 and dvr0. I can't find anything called headend0 on my computer anywhere. And in Kaffiene when I try to configure the device it says STV090x Multistandard and it says "device not connected". What does all this mean? The C-band co-ax is connected directly to the TBS6925.