Openbox Power supply Fault

[anotherdude]

Friends Openbox is rebooting after around 5 minutes and then continues to reboot after maybe 30 seconds of being on after this.

As we have a Openbox i tried our power supply in his box and it now works fine so it's a power supply issue

His power supply at the power input (figure of 8) the connections have actually lifted off the board (traces lifted), I thought it may of been a intermittent connection so done a wire bridge for each connection but made no difference.

Don't suppose anyone has any ideas on what causes a reboot on these, guessing the voltage drops for a second or 2 then the box turns off and the power comes back.

[budm]

Re: Openbox Power supply Fault

Did you check to see if the output voltage is swinging up and down? It may have bad start up cap (the black small Lytic cap next to the ZD2).

[anotherdude]

Re: Openbox Power supply Fault

Did you check to see if the output voltage is swinging up and down? It may have bad start up cap (the black small Lytic cap next to the ZD2).

there with the power supply cable disconnected from the main board

12v goes from 11.9 to 12
24v goes from 23.2 to 23.3
5v reads 5.2

connected to the mainboard

24v jumps around between 26.4v and 26.5v
12v jumps around 13.5v and 13.6v

wierd thing is it only reboots when a SAT signal is connected

[anotherdude]

Re: Openbox Power supply Fault

ok seems i get different readings when the box has a SAT signal connected

the 24v starts at 26v then as the box has booted fully it sits at 24.1v then when the box reboots it drops down to 22v

the 12v starts at 12.6v then at reboot drops down to 11v then once booting goes to 13v then back to 12.6v once booted

5v starts at 5.1v then at reboot drops down to 2v then back up to 5v once booted


still be looking at that startup cap?

ok think you may be right, box is at the point of rebooting every 30 seconds to a minute, I applied some heat towards the back of the Power supply and the box does not reboot anymore, if I stop the heat for about 1 minute or so the box reboots again

[budm]

Re: Openbox Power supply Fault

"5v starts at 5.1v then at reboot drops down to 2v then back up to 5v once booted" This is where the problem is, this 5V is used to run to logic circuits, so it can be just bad startup cap, filters caps. I would recap the board.

[anotherdude]

Re: Openbox Power supply Fault

"5v starts at 5.1v then at reboot drops down to 2v then back up to 5v once booted" This is where the problem is, this 5V is used to run to logic circuits, so it can be just bad startup cap, filters caps. I would recap the board.

thanks, ordered and hopefully sorted

thanks again

[fas1]

Re: Openbox Power supply Fault

Hi, I had a similar issue with an openbox, it turned out to be a firmware issue.

[stj]

Re: Openbox Power supply Fault

for those not sat skilled,

the lnb uses 14v or 18v depending on the polarity of the signal that is selected.
and the voltage can have a 22Khz tone modulated over it to switch from low to high band.

to make things worse there is DiSeq a system of sending digital commands to the lnb by using the 22Khz tone to send binary data.

if the lnb effects the box, it can be caused by a bad lnb of water-damaged/badly terminated cable.
but it's usually worn caps in the psu that cant stop the lnb stuff backing up into the rest of the system.

[anotherdude]

Re: Openbox Power supply Fault

for those not sat skilled,

the lnb uses 14v or 18v depending on the polarity of the signal that is selected.
and the voltage can have a 22Khz tone modulated over it to switch from low to high band.

to make things worse there is DiSeq a system of sending digital commands to the lnb by using the 22Khz tone to send binary data.

if the lnb effects the box, it can be caused by a bad lnb of water-damaged/badly terminated cable.
but it's usually worn caps in the psu that cant stop the lnb stuff backing up into the rest of the system.

ye i'm sure the LNB/tuner isn't the issue as the box worked with another power supply

Replaced all caps apart from the large one, still the same


could the class X2 cap be failing?

[budm]

Re: Openbox Power supply Fault

The circuit will still function with X2 removed, it is for AC noise filter.
So if you heat up the board, will it start working again?

[anotherdude]

Re: Openbox Power supply Fault

The circuit will still function with X2 removed, it is for AC noise filter.
So if you heat up the board, will it start working again?

ye, thats it if i gave it heat towards the back of the board it would work until it cooled again, anything else in that area that would react to heat?

seems there must be a known fault with this version of power supply as looking again mine vs this has a different setup as do the replacements