Brand new DM518s from dealextreme with no "service searching" option

[pacmyc]

I guess this problem is due to that the receiver can't find the tuner.
I opened the box and relized that the coil L704 is broken.
In the thread dm500\22khz... i found a datasheet (F.pdf) that seems to be my receiver, and according to that one the coil's name is 331M-R.
Could I replace this faulty one with this? https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=58-114-01&toc=20298

Also on another forum one user tells me that I have no tuner on my motherboard.. Well it's true, I can't see any tuner on it. I googled for DM518 and found more pictures of this motherboard, and on those
I cannot see anything tuner-like neither. Maybe the tuner is so small that it fits on the underside of the motherboard?

 

[Analoguesat]

If its brand new send it back as faulty. Then buy something decent - those 500 clones are poorly built at the best of times

 

[TJExcalibur]

Under a Google search it looks like there are loads of problems with that receiver. The coax input usualy connects to the tuner, on yours it appears as if nothing is there. If its new send it back.

 

[pacmyc]

I cant find any picutres of that motherboard and with a tuner. Could you please provide me the links to those pictures? I would like to use them for claiming refund from DX.
So replaceing this L704 will not do anything good you think? You are sure that its missing the tuner?

 

[TJExcalibur]

This is a DM, not sure which one but it gives you some idea.

 

[Llew]

I guess this problem is due to that the receiver can't find the tuner.
I opened the box and relized that the coil L704 is broken.
In the thread dm500\22khz... i found a datasheet (F.pdf) that seems to be my receiver, and according to that one the coil's name is 331M-R.
Could I replace this faulty one with this? https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=58-114-01&toc=20298

Also on another forum one user tells me that I have no tuner on my motherboard.. Well it's true, I can't see any tuner on it. I googled for DM518 and found more pictures of this motherboard, and on those
I cannot see anything tuner-like neither. Maybe the tuner is so small that it fits on the underside of the motherboard?
View attachment 38165View attachment 38166View attachment 38166

The tuner is the small chip below the LNB socket, in the enclosing white rectangle. Also in there is the larger chip, the demodulator IC. In most receivers, these would be covered by a metal shield to minimise radiation artefacts. Obviously not considered important enough by the designer to warrant the extra cost of a bit of tin...

 

[pacmyc]

The tuner is the small chip below the LNB socket, in the enclosing white rectangle. Also in there is the larger chip, the demodulator IC. In most receivers, these would be covered by a metal shield to minimise radiation artefacts. Obviously not considered important enough by the designer to warrant the extra cost of a bit of tin...

Ok, so you think it's worth to try to replace the faulty coil L704 ?
I dont think I will send it back, takes to much time.. Also I have payed customs for it, which I will not get back anyway..

 

[Llew]

Ok, so you think it's worth to try to replace the faulty coil L704 ?
I dont think I will send it back, takes to much time.. Also I have payed customs for it, which I will not get back anyway..

It's the same value and SMD ferrite choke type as the one indicated on the diagram, so I would be inclined to replace it, although if the old coil has been shorted or open-circuited by another component, the fault may still be present.

 

[pacmyc]

It's the same value and SMD ferrite choke type as the one indicated on the diagram, so I would be inclined to replace it, although if the old coil has been shorted or open-circuited by another component, the fault may still be present.

Yes of course. I think the problem was there already when I received the box, cause I heard the sound from it banging into the motherboard when shaking it. But of course I dont know if it broke when they connected it in the factory.. But to me it looks like that it has physically broken by something touching it,, if it had been a short or something I guess most likely it would just have burned of the lead on it, not breaking the whole thing on the middle.

So PISN-331M works the same as 331M-R. Now I just hope that the pdf sheet really is for my motherboard :S

 

[pacmyc]

Got it up running!
Thanks all for your inputs on this issue. I bought the coil from elfa (as linked to in earlier post).
The new coil was much bigger than the old one, so I had to compromise =).. Works nice, finds (i think) all channels that my other receiver find.. However, there's one TP that I cant get a lock on, 11642 H, 27500, 3/4 on Hotbird.. Thats strange cause i never had problem with this tp with any other receiver, and i dont think this one is among those that are weekest.. (from Sweden, Stockholm).

 

[Llew]

Got it up running!
Thanks all for your inputs on this issue. I bought the coil from elfa (as linked to in earlier post).
The new coil was much bigger than the old one, so I had to compromise =)View attachment 38183.. Works nice, finds (i think) all channels that my other receiver find.. However, there's one TP that I cant get a lock on, 11642 H, 27500, 3/4 on Hotbird.. Thats strange cause i never had problem with this tp with any other receiver, and i dont think this one is among those that are weekest.. (from Sweden, Stockholm).

Good to hear it's working again pacmyc. Do you have a DECT phone nearby? That frequency falls within the DECT band and may be causing interference - especially as the tuner chip is not shielded

 

[Fano]

Those 518 receivers are garbage .
I bought one last year and the tuner in it was faulty too,it had huge ber on every channel.

I dont like the way the tuner is surface mounted on the main board,I prefer the Dm500 tuner design .
The 518 is very flimsy build quality and has no scart connection.

 

[fergyc]

I had a dodgy DM500 that only works if the cable is in a certain position. When I set it up I have to screw and unscrew until it locks!

 

[Llew]

I dont like the way the tuner is surface mounted on the main board,I prefer the Dm500 tuner design .

This is the way to do it when the chip is onboard, as with my DM8000: under a metal shield -

 

[pacmyc]

Good to hear it's working again pacmyc. Do you have a DECT phone nearby? That frequency falls within the DECT band and may be causing interference - especially as the tuner chip is not shielded

Ok.. So the receiver would have a bad influence on the phone, or the phone would make my satellite signal worse?
Or both ways?
Do you have any idea how I could make a shield fot the tuner?

lso, what about radiation from the receiver, around the room..? If it could have an impact on a DECT phone, it doesnt sound to helathy to be around it.. Anyway to measure?

Is there anything else I can do to improve the receiver?
I also have BER on some channels, byt they still seems to work nicely,,

 

[Lazarus]

The Receiver acts as a Faraday cage and will be virtually immune to DECT phone interference: However, DECT phone signals can and do exploit weaknesses in cabling and connections. So you need to ensure there are no joints or damage to the cable, that it is proper double-screened satellite grade, and that any fcelpates are good quality ones that maintain screening throughout.

It is a simple matter to establish if a DECT phone is interfering ................... turn the base station off at the mains.

If that solves your problem, either improve the satellite cabling as described, or shift the DECT base elsewhere.

As DECT uses approx. 1880MHz, it can disrupt Satellite TPs around 11630 MHz and 12480 MHz ( which are downshifted by the LNB to ..... 1880 MHz)

 

[pacmyc]

The Receiver acts as a Faraday cage and will be virtually immune to DECT phone interference: However, DECT phone signals can and do exploit weaknesses in cabling and connections. So you need to ensure there are no joints or damage to the cable, that it is proper double-screened satellite grade, and that any fcelpates are good quality ones that maintain screening throughout.

It is a simple matter to establish if a DECT phone is interfering ................... turn the base station off at the mains.

If that solves your problem, either improve the satellite cabling as described, or shift the DECT base elsewhere.

As DECT uses approx. 1880MHz, it can disrupt Satellite TPs around 11630 MHz and 12480 MHz ( which are downshifted by the LNB to ..... 1880 MHz)

I tried as you suggested with the DECT base station switched off, no difference. Than I moved the dreambox to another room any connected it there. And the TP works..!
I checked the cables (in the first room the sat cable goes via a diseqcs) and also via a special thin cable trhu the window, in the other room it goes straight to LNB with cable sqeezed in around the window..
So I removed this very thin part (its like a short cable ~20 cm, with 1 female F connector in both ends), and mounted the cables together, and now it works in room 1 as well. So, I guess this stupid thin thing is not very good to the signal,,
You however gave me the hint about bad cables, so its thanks to you that I tried this

Now, I get som BER in the first room on this TP, but it locks on it.

 

[pacmyc]

This is the way to do it when the chip is onboard, as with my DM8000: under a metal shield -

Should the shield be connected to ground?

 

[T_G]

Yes those thin through-window connectors are pretty crap from my experience. I had some problems with then a long time ago, so I drilled a hole into the window frame and got rid of it.

Regarding the shield: Yes it should be grounded, as any shield would.

 

[Llew]

Definitely needs to be grounded.. At two or more points around the shield if possible. Don't know the layout of your particular STB's board, but if you're thinking of fabricating one for yours, you will need to make sure you can find some good ground plane points to solder to.