Sanyo DP42840 P42840-05 set wont turn on

[Sinfury2112]

working on this set for a friend, psu seems to have all its voltage, no front led, no visual signs of burned anything on the boards, has all 24v 12v 5v ps-on is 2.8v no standby led at all is this maybe a mainboard? I uploaded a schematic will try get pics soon. I take it these sanyos are junk from the get go as I have 3 them same symptoms thanks for looking

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

if I unplug 5pin connector K8L on the anolog board that's connected to mainboard, the backlights come on if that helps any

[budm]

Re: Sanyo DP42840 P42840-05 set wont turn on

That means the inverter and the power supply is OK.

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

with everything connected is it poss to force the set on? like gnd/ps-on? thx budm

[budm]

Re: Sanyo DP42840 P42840-05 set wont turn on

You need to remove the PS-ON wire first before using the resistor (330~1K Ohms) between PS-ON and 5VSTBY to force on the power supply.

[CapLeaker]

Re: Sanyo DP42840 P42840-05 set wont turn on

umm... you got PSon though...

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

I read somewhere before some these sets get in the stuck on position?

[budm]

Re: Sanyo DP42840 P42840-05 set wont turn on

umm... you got PSon though...

"ps-on is 2.8v" I know, so I do not know why he still wants to do the force on.

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

so its already on?

[adgor]

Re: Sanyo DP42840 P42840-05 set wont turn on

The DP42840 Sanyo series have main board problems and new boards aren't available. Some kits are available (check ebay) but the smd IC's are difficult or impossible to replace without the right equipment. Problems are usually related to data corruption on IC5750 but other components can be bad too.

[CapLeaker]

Re: Sanyo DP42840 P42840-05 set wont turn on

so its already on?

Yes. You have 2.8V on the PSon pin. That is sufficient voltage to turn on the PSU.

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

well thanks everyone for the post

[CapLeaker]

Re: Sanyo DP42840 P42840-05 set wont turn on

"ps-on is 2.8v" I know, so I do not know why he still wants to do the force on.

We will see... I this case I don't know either why... unless it would come on turn off etc.

[awyatt2]

Re: Sanyo DP42840 P42840-05 set wont turn on

mainboard problem,i had the same set ,same symptoms. fortunately it was under warranty the main was like 170. then the tv was less than a yr old.

[CapLeaker]

Re: Sanyo DP42840 P42840-05 set wont turn on

well thanks everyone for the post

proof is that all other voltage rails are up and running too. So you have to have PSon.

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

this morning I decided play with this set was very quiet and I heard a faint sound the set was on with volume turned way down no backlight and no led on front panel wtf

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

now nothing, I understand after 3 power failures this set goes into standby mode, how long till it resets itself after unplugging?

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

Note: If power failure is detected 3 times in 15 minutes,
the set will enter the standby mode and cannot be
switched On.To reset the operating programs of the
sub_CPU it is necessary to disconnect the AC cord
for a short time.

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

this morning I decided play with this set was very quiet and I heard a faint sound the set was on with volume turned way down no backlight and no led on front panel wtf

help

[Sinfury2112]

Re: Sanyo DP42840 P42840-05 set wont turn on

im using a mainboard out of a P42740-04 in this set has sound but once I plug main video cable nothing schematics shows same pinout for video sound is now working just no video! if I leave lcd plugged into mainboard wont come on no sound but when it is unplugged works fine I know its not right board but I think it will work something else is wrong somewhere