DM8000HD tuner connector vdc measurements.

No idea if it will be useful, but it is an attempt to provide an opportunity to find a tuner error.

Good luck!

(Thank you to Johnny_B for publishing it)

All the best about hardware/support from Johnny_B, link :
http://jb8a8f8.com
http://jb8a8f8.nl

I think this may have helped me solve a problem I've been having.
For me, the 6V feed is only measuring 3.68V. I have followed it back to the PSU supply pin no.3 and am only getting 3.77V instead or the required 7V.

Can you recommend a solution to fix this. I assume a component in the PSU is defective, but I am not skilled enough to follow the circuit back to the defective component.

I have replaced the 4 x 35V caps as I thought that may have been an issue.

Any help you can provide would be greatly appreciated.

Regards,
Hoffy.

You're on the wrong track because the pin 3 could have 3 to 7 vdc.
This value depends on the motherboard, not really from the psu.

The basic voltage for the main board and external tuners are 12/5 and pin 10 3.3 vdc.

Nevertheless you need give more information as,
Failure of all tuners, in/external.
Failure of the external tuners.
Failure of the motherboard tuners.
Other issues..

Thanks for the feedback.

The issue I have is the box boots fine without Tuner 3 & 4 installed (I have 2 DVB-T tuners installed). If I install any of the DVB-T tuners, the boot hangs around 15% progress. I have tried a couple different images, they both stop at the same point. Pin 3 on the main power connector has odd readings. Your Ohm reading for that pin should be 52.3 or 47.3 Ohms. Mine reads 39.07 Ohms and never stabilizes.

The reason I was thinking the Voltage is incorrect was, according to your image of the Tuner voltage readings, the Measurement for 6V in to the caps (around the tuners) is 3.68V, and the 5V out for tuners is only 2.67V. The measurement for 3.2V & 12V in that area are correct.

Having more of a look at your picture just makes me more confused.

Like I said, the 6.6V feed around the tuners is only measuring 3.68V. This is obviously causing the output (meant to be 5V) measuring only 2.67V.

What could possibly be causing that 6.6V feed to be so low?

I noticed in the picture of the external tuners, there is one connection that requires 5V to the external tuners. In my mind, that may be a reason why my DVB-T tuners are not working.

Regards,
Hoffy.

Just went to start my box and make some more measurements and it would not boot. All I had was the initial Dream logo just before it shows the SSL version. Whilst in that state, I measured the main power connector and most things were ok, but that pin 10 you mentioned was jumping all over the place. I could not get a steady V reading on it.

Switched the box off, then back on and it began to boot. Once it was booting, pin 10 had a steady 3.35V.

Any clues as to what would cause pin 10 to jump around like that? Seemed to be something switching on/off rapidly..

Regards,
Hoffy.

The pin 10/3.3vdc is a output voltage from the power supply and may not drop, even with booting.

If it does, then several parts as the tuners will fail.
This could causes by two sides,
Psu, 3.3v regulator can't bare the amps consumption.
Motherboard, mainly tuners, and one of the tuners consumes more amps than normal.

See if it makes a difference if you not use the external tuners, or one of them.

However, I think it's a psu issue.

I believe you may be correct regarding the psu problem. It used to work fine with all components installed. Last night, this issue occurred with none of the external tuners installed.

Do you happen to know what current can be drawn from each rail? I have a a few components running in there.
3.5" WD Green HDD, Slim line DVD-Rom, 8cm cooling fan.
As I said, it used to all run.
Is there a better psu than the original clone psu?

Regards.

I have no technical specifications of the psu, so also not from the amps outputs.
But based on the pin 10 3.3v and the U1 which is a MP1484.
3A, 18V, 340KHz Synchronous Rectified Step-Down Converter.

This line can tolerate 3A.

Fan, hdd etc use the 5/12v

However the input of the MP1484 is 5 to 12v, so it's a bit related.
But in that case you must also see a unstable 5 or 12v.

Q: Is there a better psu than the original clone psu?.
Depends on brand and type..
As the original dm8000hd psu from panasonic NPX654M-3 / NPX654M-4 or ETXEZ654M7F seems to be better.
But even this may fail over time use.

Thank you very much for the help.

I am hoping to do a few more thorough tests in the next few days.

One thing that still troubles me is, in the picture, relating to the voltages around the tuners, there is a 6.6V input to the capacitors, then a 5V output from the converter? My voltages there are not correct as stated in earlier posts.

Am I not understanding something there?

Yeah, this voltage could be 2 to 7 v,
However if you remove the psu, or at least disconnected from the motherboard and you add a 3.3v voltage to pin 4.

Just as this picture shows,
http://www.ourdreambox.com/ubbthreads.ph...-psu-switch.jpg

Than this pin 2 should give 6vdc or a bit higher, at least when I tested this way, with several psu's they were al 6v+.

Just decided to measure a couple old PSU's I have to see if they are any good to use. Are either of them repairable or are their measurements too far out. Anything strike you as simple? I don't think I've every replaced caps in them. Both are 25X10 code.

Original PSU was faulty when it arrived.
1 - 0.63K
2 -
3 - 29.56K
4 - 13.38K
5 - 13.96K
6 - 13.7K
7 -
8 - 8.52K
9 -
10 - 20.53K
11 -
12 - 4.7K
13 - 4.7K
14 -

1st replacement PSU
1 - 8.75K
2 -
3 - 32.98K
4 - 14.92K
5 - 15.03K
6 - 15.03K
7 -
8 - 6.0K
9 -
10 - 22.6K
11 -
12 - 4.68K
13 - 4.68K
14 -

Regards.
Hoffy

Further to this, I just got a chance to test the PSU currently in the DM.

It is the later style 5L0565.
1 - 11.9K
2 -
3 - 53.1K
4 - No Value
5 - 22.09K
6 - 21.63K
7 -
8 - 9.11K
9 -
10 - 30.36K
11 -
12 - 8.22K
13 - 8.22K

This current PSU seems ok based on that alone.

Psu 1, 14v issue.
Psu2 (2.5v) doubtful.
Psu 3 seems to me fine.