Wire Solution is final solution.



Since today our first production of DM800se were success. The only bug we have noticed (less than 5% boxes suffer that above symptoms) we successfully tested with our partners the solution and the cause. You can see on the picture the solution is simple - change R1107 from 10KOhm to 15KOhm. Such issue is visible if you apply a load to +5V branches like USB ports, SC readers and HDD. A few receivers loaded by 500GB HDD, DTT, USB Flash and 2x Smart Card inside the reader were unable to start up due to lack of power at +5V branch. We know how important is to inform our customers about the QC and known issues. We have measured 3R3 inductors and some of them are off the limit inductance and that is why some of you might to value our information.

We have received one board that had HDD "click click" problem even with HDD 0.55A. We have been playing with the PLL and we have found a simple wire can solve the issue. After adding wire we have added DTT USB tuner and also changed the HDD of 1A and for one day all OK.

Your box is interesting us very much. I assume your HDD consumes about 0.85A or more and you are using old DTT with higher power consumption. In this case I would courteously ask you to install R1107 vary from 10K and 15K. Something like 22K or more. We have heard about 3 such cases. It would be helpful anyway. It depends not just on 3R3 inductors but also other Capacitors inside the circuit. The most easy way how to adjust PLL filter of the IC is alter the R1107.

A few tests - we have removed R1107 and made short circuit as Toysoft did with his 15 Ohms. OK, we did a few tests - finally we heard the "CLICK CLICK" HDD sound. Well as we use 0.55A HDD we made additional parallel resistor out of heating string used in HOT AIR stations. Firstly we used 2.5 Ohm so the total current ought to be about 3A. 2A via wire resistor, 0.55 via HDD and about 0.38A via USB DTT. The box started booting and the wire got hot! Than we heard the sound - the voltage dropped to 4.46V on HDD that we assume is critical. Well we have changed the wired resistor to 10 Ohm to get 0.5A stable current via hot air wire and another 0.55A via HDD. The box is running fine and the current is higher than 1A. The conclusion is simple. With 10K resistor do not use HDD with higher current but something like we had ie. 0.55A than all is fine and nothing is necessary to alter. If you insist using big or old HDD with internal power supply I would modify the PLL filter by R1107 by a wire over the R 1107 (make it short) is also OK to move PLL (Phase Loop Lock) filter working well.


To make all clear - we used 3R3 inductors but the correct inductor is 3R5 and this value is critical. All new production is with 3R5 inductors now so w/o any power issue with 1A current HDD. You can check easy if your Ferrari receiver is from our very first production than I would prefer HDD with lower current consumption and than there is no modification necessary or later than same as genuine.

The use of the U1100 LTC3850 was in my opinion a wrong approach, at least for the HDD power supply.
This is in the later designs also changed considerably by making two separate 5V supply's.

It is simply too much for the U1100 to provide all 5v on the motherboard.
Usually it works fine especially if there is not used a hdd, but if this circuit receives a malfunction, because the hdd used too much, or fails, it can give more damage to other components on the board.
The result is often an irreparable or hard to repair problem with too much damage.

A better solution is to separate the HDD power supply of this circuit, and supply it with an additional LM2596 DC-DC converter module.
These are cheap on ebay to found, a small version as 2 amp is sufficient.

Thank you Johnny ! Do you have a schema that would allow people to modify their DM800HDse motherboard to not risk to destroy their DM800HDse using too much power / an internal HDD.

Thanks,

TS

Although I have already a lot of these type of motherboards modified, I have taken no picture of it.
But I will make the next week a drawing of it.

It is not a hard thing to mount, only 3 wires.
12v +/- input, and a 5v + output wire.

Thank you, but then we have to modify the internal connector / support for the DM800HDse Hard Disk. As all comes thru the PCB connected to the connector on the motherboard for the internal HDD.

TS

It is best to wait for the drawing, which I will explain it well.

For safety reasons, I have decided to give no information to separate the HDD 5v from the U1100 LTC3850 circuit.
This is because there are several versions motherboards.

I invented an alternative solution, which is safe to build.

Beautiful as always your work is like a Diamond, really nice, clean and perfect.

Thank you so much !

TS

In my case when I put the pendrive (with the picons) when changing channels or restarting the DM the screen turns black. If I only change the R1107 will the problem be solved?

You should ask to Johnny, but I don't think this could fix it. Did you tried to reboot the box and remove the HDD for example ? To see if you still have the same problem or not ? Which image are you using, did you tried with another image ?

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