Sanyo CE32LD47-B flashing standby light

[blib]

Hi Guys
This set has the Vestel 17PW26-4 power supply.At switch on the 24volts and 3.3volt lines come up that supply the inverter but no enable voltage on pin 12 PL802. After a few seconds power supply powers down then restarts then powers down again then powers down for good with standby light constantly flashing.Unplugging the supply to the inverter produces the same symptom.Does anyone know if this board will work without a load on it.Is it shutting down because the back lights are not starting?Any help in diagnosis will be appreciated.
Thanks.
Dave.

[selldoor]

Re: Sanyo CE32LD47-B flashing standby light

Tom66 knows a lot about these vestel boards - hates them- so you will probably get him going.
Does the backlight flash on at all during startup? Is there any sound?
Is there any noises, hissing ,ticking, have you been trying it with a known source
dvd or pc.

[multimeter]

Re: Sanyo CE32LD47-B flashing standby light

on pin 12 of pl802 what resistance reading do you get with respect to cold ground?

[selldoor]

Re: Sanyo CE32LD47-B flashing standby light

I believe a lot of the boards suffer from poor soldering , cold joints so can you get a picture of the back of the board - the front one is really good- thanks.

[multimeter]

Re: Sanyo CE32LD47-B flashing standby light

they do suffer BADLY with cold joints,ive repaired a few vestals now,everyone had cold joints,in fact in one of my other posts,there was one where i could pull the caps off without unsoldering them,well shocked !,and i found one with a galvanised roofing nail cut down,and used as a 3.15 antisurge fuse !,the bridge was in meltdown ,totally blown to pieces only the legs visable lol,the makeshift fuse was ok though

[blib]

Re: Sanyo CE32LD47-B flashing standby light

Thanks for the replies.Pin 12 to ground is 8.9Kohms with inverter connected.I have found a short between pins 1 and 3 of IC831 with pin 3 disconneced but I cant identify the device.

[selldoor]

Re: Sanyo CE32LD47-B flashing standby light

Thanks for the replies.Pin 12 to ground is 8.9Kohms with inverter connected.I have found a short between pins 1 and 3 of IC831 with pin 3 disconneced but I cant identify the device.

Picture is no good for us to help look for cold joints - perhaps tryagain in natural light tomorrow?.
Looks like a Voltage regulator which is odd for an IC number I wonder if that relates to something missing off the board or on the other side ( have made that mistake before and it could be a mosfet) - do you mean you cant read the part number?
Try and clean it with isopropyl alcohol and use a magnifier

[blib]

Re: Sanyo CE32LD47-B flashing standby light

IC831 turned out to be a red herring.I lifted it off the board and i can see now its just a diode with only two pins connected to the pcb and it reads OK.Cant see any bad joints and posting a better picture of the print side.Bye the way back light does not flash at start up.
Does any one know if this power supply will work in isolation and if not is there a way to test it? I still think it might be shutting down because of no voltage on pin 12 of PL802 which might be the back light on signal.Just dont want to get another power supply and find i have the same problem.

[multimeter]

Re: Sanyo CE32LD47-B flashing standby light

Thanks for the replies.Pin 12 to ground is 8.9Kohms with inverter connected.I have found a short between pins 1 and 3 of IC831 with pin 3 disconneced but I cant identify the device.

8.9kOhm is saying that rail isnt shorted,what is the reading with inverter disconnected?

[blib]

Re: Sanyo CE32LD47-B flashing standby light

9.5Kohms

[selldoor]

Re: Sanyo CE32LD47-B flashing standby light

Can you check the joints marked with a magnifier and resolder any you think are bad- Its hard to tell on a picture but a few look to have cracks/rings.

[tom66]

Re: Sanyo CE32LD47-B flashing standby light

Sounds like a main board issue more than anything, check PS ON pin.

[ben7]

Re: Sanyo CE32LD47-B flashing standby light

Are there any other voltage rails on the output? It sounds like there could be a short, or a rail is not reading the correct voltage.

[blib]

Re: Sanyo CE32LD47-B flashing standby light

Hi Tom
There are no markings on the pcbs showing P-on but
referring to my first pic showing the socket connecting to the main if pin 1 is top left and pin 15 is bottom right then voltages are as follows.
Pin 1= 0.00v
Pin 2= 8.45- 8.57v (fluctuates)
Pin 3=2.92v
Pin 4= 0.00v
Pin 5= 0.00v
Pin 6= 1.75v
Pin 7=5.04v
Pin 8=3.42v
Pin 9=0.1v
Pin 10=0.1v
Pin 11=0.1v
Pin 12=0.1v
Pin 13=0.1v
Pin 14=0.1v
Pin 15=NC
Pin 16=0.09
Pin 17=0.00
Pin 18=0.59
Pin 19=0.59
Pin 20=0.59
Pin 21=3.43
Pin 22=0.00
Pin 23=1.75
Pin 24=0.00
Pin 25=0.00
Pin 26=0.00
Pin 27=0.00
Pin 28=NC

[tom66]

Re: Sanyo CE32LD47-B flashing standby light

Schematic
http://tgohome.com/ServiceManuals/Vestel/Vestel_17PW26_[SCH].pdf

Can you determine which pin is which now? Of interest are the 5VSTBY and 3.3VSTBY pins, as well as ST_BY and SW_SWITCH.

[vinceroger69]

Re: Sanyo CE32LD47-B flashing standby light

maybe worth checking this thread out
https://www.badcaps.net/forum/showthread.php?t=16418

[blib]

Re: Sanyo CE32LD47-B flashing standby light

Tom, The link to the schematic seems to be broken .

[blib]

Re: Sanyo CE32LD47-B flashing standby light

Ok got the schematic now thanks

[blib]

Re: Sanyo CE32LD47-B flashing standby light

Worked out the pins and done some more checks and I have +5vstby on pin 14 and +3.3stby on pins 15 and 16 of PL816 permanently. All the other voltages come up for about 5 seconds then die then come up again then die permanently leaving the flashing front led.

[multimeter]

Re: Sanyo CE32LD47-B flashing standby light

can you esr the 2 caps next to the large transformer?,just there, is a 8 pin chip,one of those caps should go to vcc on that chip,it will be the startup cap,if you dont have an esr meter,find the datasheet for that chip,find the vcc pin,note the voltage,power the tv on ,measure that voltage on vcc,this does seem to be a startup cap failiure,beacause of the constant voltage up voltage down voltage up etc,i think there should be around 22v going to vcc,not sure tho