Samsung LE40R88BD locking up and power cycling

[Lee]

LE40R88BDX/XEU, not quite the usual cycling with relay clicking on
startup as this one does start up but then locks up and power cycles
after varying amounts of time.
Checked the power supply, which appears to have been built with decent
caps in this example, rather than the usual junk, anyway all the
voltages 'scope clean as do all the ones I checked on the main board.

I have replaced the eeprom (24C256) and performed a factory reset which
apparently allowed it to work faultlessly for an hour until it locked up
watching Freeview and reverted to the original problem.

However, turning off the digital watch dogs in the options table does at
least allow it to stay powered, albeit with Freeview (integrated digital
tv for those not in the UK ) not working.

As it appears to work in this state I'm going to leave it like it, as
it's being used with a satellite box anyway and HDMI seems to work fine.
Unless anyone has any ideas?
I don't have access to a newer firmware file and for some reason this
particular mainboard revision isn't appearing at the usual suspects,
maybe it's just too old now

 

[N_Cook]

On 19/06/2014 13:58, Lee wrote:

LE40R88BDX/XEU, not quite the usual cycling with relay clicking on
startup as this one does start up but then locks up and power cycles
after varying amounts of time.
Checked the power supply, which appears to have been built with decent
caps in this example, rather than the usual junk, anyway all the
voltages 'scope clean as do all the ones I checked on the main board.

I have replaced the eeprom (24C256) and performed a factory reset which
apparently allowed it to work faultlessly for an hour until it locked up
watching Freeview and reverted to the original problem.

However, turning off the digital watch dogs in the options table does at
least allow it to stay powered, albeit with Freeview (integrated digital
tv for those not in the UK ) not working.

As it appears to work in this state I'm going to leave it like it, as
it's being used with a satellite box anyway and HDMI seems to work fine.
Unless anyone has any ideas?
I don't have access to a newer firmware file and for some reason this
particular mainboard revision isn't appearing at the usual suspects,
maybe it's just too old now

Or is it just coincidence and an intermittant fault brought on/cleared
by close handling?.

 

[Lee]

On 19/06/2014 16:38, N_Cook wrote:

Or is it just coincidence and an intermittant fault brought on/cleared
by close handling?.

I did wonder that, in particular heating the board changing the eeprom,
but prodding, freezing and heating seems to make no difference, whereas
a reset does.
I'm thinking a failed bga connection or maybe faulty dram. The main
chip does run quite hot...

 

[Mark Zacharias]

"Lee" <cyberwitch@ukonline.net> wrote in message
news:c0gfqkFg71qU1@mid.individual.net...

On 19/06/2014 16:38, N_Cook wrote:


Or is it just coincidence and an intermittant fault brought on/cleared
by close handling?.

I did wonder that, in particular heating the board changing the eeprom,
but prodding, freezing and heating seems to make no difference, whereas a
reset does.
I'm thinking a failed bga connection or maybe faulty dram. The main chip
does run quite hot...

Not sure if this relates to yours, but I have seen on some recent vintage
Samsungs the cable between the main board and power supply develops a burned
and intermittent connection at the power supply side. A close examination of
the connections would reveal if this is the case.

Mark Z.

 

[Lee]

On 22/06/2014 01:59, Mark Zacharias wrote:

"Lee" <cyberwitch@ukonline.net> wrote in message
news:c0gfqkFg71qU1@mid.individual.net...
On 19/06/2014 16:38, N_Cook wrote:


Or is it just coincidence and an intermittant fault brought on/cleared
by close handling?.

I did wonder that, in particular heating the board changing the
eeprom, but prodding, freezing and heating seems to make no
difference, whereas a reset does.
I'm thinking a failed bga connection or maybe faulty dram. The main
chip does run quite hot...


Not sure if this relates to yours, but I have seen on some recent
vintage Samsungs the cable between the main board and power supply
develops a burned and intermittent connection at the power supply side.
A close examination of the connections would reveal if this is the case.

Mark Z.

It looked ok at first glance, but I will examine it more closely. Thanks.

 

[Mark Zacharias]

"Lee" <cyberwitch@ukonline.net> wrote in message
news:c0o09eF2otrU1@mid.individual.net...

On 22/06/2014 01:59, Mark Zacharias wrote:
"Lee" <cyberwitch@ukonline.net> wrote in message
news:c0gfqkFg71qU1@mid.individual.net...
On 19/06/2014 16:38, N_Cook wrote:


Or is it just coincidence and an intermittant fault brought on/cleared
by close handling?.

I did wonder that, in particular heating the board changing the
eeprom, but prodding, freezing and heating seems to make no
difference, whereas a reset does.
I'm thinking a failed bga connection or maybe faulty dram. The main
chip does run quite hot...


Not sure if this relates to yours, but I have seen on some recent
vintage Samsungs the cable between the main board and power supply
develops a burned and intermittent connection at the power supply side.
A close examination of the connections would reveal if this is the case.

Mark Z.

It looked ok at first glance, but I will examine it more closely. Thanks.

We've also seen wireless modules and jog assemblies cause this type of
thing.

Sheesh. For the days when basic troubleshooting was enough. Too much purple
magic in this new stuff.

Mark Z.