DM500S shows Frontend: Unknown ( tuner fault )

[Fernbay]

Just for you LP, heres a blow by blow

The answer is the 'plug in tuner'

Tested remote (checked OK). Changed IR board twice with new ones - didn't fix it.
Replaced main board with new twice - still didn't fix it
So, that left the tuner

Went over it with a meter on diode test & found the cap C6 was short.
Replaced it & found problem was solved

Sheesh how did you trouble shoot that one? You wouldn't think it would be a cap on the tuner board!

Leroy

[LeroyPatrol]

Ah the plug in tuner. Thanks for that. There's another good reason them.

Leroy

[gw1]

Tuner problems? See also: due to damaged LT1930 chip.

[uutgrunn]

Hi, sorry for my bad english. I also have a DM500s with a faulty tuner.

I saw that the fault could be in capacitor c4 and c6. These are ceramics,
but what are these values?

What else should I check?

If you have more info, you can also e-mail me directly:
dm500nl[atthingy]gmail[dot]com

Thanks in advance!

[mmsuranjith]

Gentlemen,

Thanks for all your help, my first DM500S which showed "Frontend:Unknown" is now repaired, I went throught the tricky process of installing a new ALPS tuner and straight away got "Frontend:Satellite", its scanned OK. Subsequently I installed PLI Iolite and all back to normal.

For my second DM500 which lost its +30v for the varicap tuner, it was a bit more tricky........this supply is generated on the underside of the tuner sub board with a 5 pin unknown IC and inductor etc. Discovered a minimum of +14v is adequate for the varicap supply, did a shonk and installed a 9v battery with negative connected to the incoming +12v Dreambox supply giving +21v and this I connected to pin 5 of the tuner (varicap supply).

When powered up the battery supplies 700uA so it should last a while. Later I will replace the battery with a 555 driving a voltage tripler, but for now I have two working DM500's.

Thanks for all you inspiration.

Regards,

how can i connect 30v in? tuner side pin 5 empty ?

[mmsuranjith]

Thanks for saying thanks.

You did a fantastic job isolating that component to be the fault.


C4 underneath the Alps tuner unfortunately is on the little daughter board.
A lot of unsoldering to get to a nasty little cap...

dear sir ,

can you tell me c4 capacitor value


thank you....

[cwispy]

dear sir ,

can you tell me c4 capacitor value


thank you....

Use about a 1uf 50v ceramic. Its not that critical its the exact same value that was on there.

[ozfox]

Hi all,

There is some great reading in this thread on fault finding, thank you all for the info.

Is anyone able to advise the part value of the diode D2. It is located on the underside of the tuner card BSBEI-703A.

Thank you

[limit]

hi.....i have similar problems but i dont know where to start.......

when i check in dreambox in i can see Frontend:Satellite

but any how i cant tune on any channels......when i try to scan box finds only 1 transponder maybe 8 channels only ......but still no picture i get on them.....

Also i notice tuner temperature is hot .......i guess there's a short on it same where ......??????

how i can repair pls....??????where to start???

many thanks...

[limit]

sorry i make a wrong post can mod's delete this ..thanks

[LeroyPatrol]

why not pm fernbay and buy another tuner?

[dorcky]

oh alright, here you go......

Hello, everyone, I want to ask if anyone of you have the rest of the schematic for DM500 witch is equipped whit tuner like in the picture from above picture. Thank You!

[limit]

Went over it with a meter on diode test & found the cap C6 was short.
Replaced it & found problem was solved

hi..can you pls tell us the value of the C6......????thanks

[sanjin]

My genuine Dreambox DM500S with ALPS tuner and running Dream release 4.2.0 17.12.2007 is not working.

If I select "INFO>About", it says Frontend: Unknown.

I have tried flashing various images and allways Frontend: Unknown.

What do I do?

Regards,

try connecting another dvb-s receiver thru loop f-connector on dm500.pick on both the same transponder.check if both works and deliver picture,if so,then is faulty a smd mosfet in dc 30v step-up converter on main board.do not use multimeter.just replace mosfet.if you get the picture nothing wrong with tuner and sub board.

[sidplayos2]

I need to replace the c725 cap but not sure what value or type it is. I tested with a 220uF/25v and the tuner works again, however I would like to replace with the correct component if possible.

I noticed on the schematic it mentions c725 = 475, and from my research on the net of smd codes the first 2 digits are the cap value, and the last digit the multiplier in pF.

So 47 x 10^5 pF = 4.7uF. Can anyone confirm I'm on the right track here? Also what would be the type of cap to use, tantalum, ceramic, electro etc?

Cheers

[cwispy]

Just checked an old board here and it is a 4.7uf ceramic.

[sidplayos2]

Thanks cwispy, works great.

Just checked an old board here and it is a 4.7uf ceramic.

[mmsuranjith]

woops wrong one, here ya go....

dear z80,


in this schematic diagram pin 5 blank(NA) , where i connect 30v and which pin to connect 30v ,

dear Z80 plz comment

[daphney]

i have fixed the 30v issue with the board shown on here { thnx }
i can lock & scan most channels but seems to miss certain ch all the time i have tryed on 2 different dishs which work fine with other boxes
i looked on bac of tuner board & seems D1 when tested with multimeter lets current go both ways
so can some1 please tell me value of that diode or what i can replace with

thanks for the info that got me this far

[mmsuranjith]

i have fixed the 30v issue with the board shown on here { thnx }
i can lock & scan most channels but seems to miss certain ch all the time i have tryed on 2 different dishs which work fine with other boxes
i looked on bac of tuner board & seems D1 when tested with multimeter lets current go both ways
so can some1 please tell me value of that diode or what i can replace with

thanks for the info that got me this far

dear,

ex plane how to solve your problem ,its help for other dm lovers