Philips 32PF5521D/10 Stuck in Standby Sortof

[QuantumCheese]

I acquired this set as a duffer, with the intention of fixing it.
I have spent quite a while on it so far, and two days ago, thought I had cracked it (not literally thankfully)

The fault is like this. Apply power. Standby led comes on RED, pretty much nothing else happens.

I have been over the PSU board and measured the outputs, they are all good and even look clean when viewed on a scope. I have measured (most if not all) of the supplementary supplies as generated on the two small signal boards and they too appear with spec.

So, i convinced myself that the fault was in the primary SSB as the second one was allegedly only a freeview tuner. I found a 'near as damn it' second hand SSB & fitted it.

Bingo, it sprang to life, the LED turned green and the TV asked me what language i would like to use....... all fine you would think........2 days later and i now have a remote with an OK button on it (long story, don't ask), i plug it back in & blow me if it's doing exactly the same as it was.

So basically, it's been having a nap for a couple of days, off power, and now it doesn't work again.

Someone, please suggest something while i still have most of my own hair! I hate faults like this!!

 

[Wabajig]

Do the caps look good on power supply? Is the PS and inverter separate? If I understand you correctly then SSB bd mean main board? Check your +24V is still live when no display? or do you see the flourescent lights on when turn it on? if so, check your t-con board for miniature tiny,tiny surface mount fuse. Also check the P-ON line and the Error line from PS to Main board cable, usually they are listed on the board. Make notes whats happening in order, chicken or the egg.

 

[QuantumCheese]

Do the caps look good on power supply? Is the PS and inverter separate? If I understand you correctly then SSB bd mean main board? Check your +24V is still live when no display? or do you see the flourescent lights on when turn it on? if so, check your t-con board for miniature tiny,tiny surface mount fuse. Also check the P-ON line and the Error line from PS to Main board cable, usually they are listed on the board. Make notes whats happening in order, chicken or the egg.

Yes all the caps look good and even measure within spec for C and even ESR
Inverter(s) are separate and it's possible to fire up the back light by hot-wiring it's control line
SSBs are basically the 'not power supply' boards, that's what Philips refer to them as in the service manual. There are two. one for main control/scaling/panel drive etc and one which adds dvb-t to the set.

I can't see any fuses on the SSB, also the (main) ssb has about 5 supplementary supplies generated on it, so i figure it has power as they all come on. the dvb-t board has 3 supplies on it all taken off the 12v o/p from the PSU. they all light up too.

if i pull the psu control line out of the connector i get some flashing LED error codes - basically telling me the PSU is not working. put that control line back in & it's back to the same old.

I haven't worked on this for a while now due to other commitments but the next thing i was intending on trying was powering the set up off bench supplies. i have enough channels, and that would but to bed the idea of a fault in the psu board for good. I hope.

As i said previously, the SSB showing the fault is a 'new' one. so unless something blew the new one (which it didn't do while i had it powered up, it happened between then and being powered up 2 days later) the fault lies in either the psu of the dvb-t.boards

i'm thinking one of the psu channels is a bit slow on the up or a power-on-good device (that i haven't located yet) is a bit twitchy - or BOTH probably!

 

[Wabajig]

Are you sure about that model #, I was looking in my database and can't find it. Where do you live? I believe 6 blinks is SSB. Does the 5v make it to the SSB? If not, then suspect P.S. Do all your other voltages come up? Are any of the LEDs lighting on the SSB?

 

[QuantumCheese]

Are you sure about that model #, I was looking in my database and can't find it. Where do you live? I believe 6 blinks is SSB. Does the 5v make it to the SSB? If not, then suspect P.S. Do all your other voltages come up? Are any of the LEDs lighting on the SSB?

Apologies for delay, i needed space on my bench so this got shelved for a bit.

Yep, it's definitely the correct model number - if you paste it into google and go the 1st hit @ philips it'll show a picture of it.
Attached is the page in the service manual detailing the psu's for the various versions of set. (full version available from elecrotanya)
I have the 32" and as far as i can tell it has no 5V supply (generated by the psu board), that's only on the 37" set.

there are no led's on the SSB. or none that i can identify.
(reading back to your previous) what's a t-con board?
and identifying which comes first, chicken egg etc is going to be a little difficult as my storage scope just added itself to the 'to fix' pile rather annoyingly!

 

[Raven Luni]

Check any relays and power transistors - thats the first thing I would do in that situation.

 

[QuantumCheese]

Check any relays and power transistors - thats the first thing I would do in that situation.

been there done that thanks

 

[Wabajig]

Do you have a picture of the power supply. No 5V means bad power supply. Check diodes and transistors for shorts and resistors for opens or value changes. Look for discoloration, as a sign of significan heat. Look for the physical first, then apply the meter only after you discharge all caps. I discharge caps through a 10 ohm 10 watt resistor with alligator leads.

 

[(*steve*)]

As a silly suggestion... Last time you removed and replaced the tuner.

Try doing that again.

Maybe there's some error state that gets reset when you do, maybe there's a poor connector, or maybe it was a coincidence. (Or maybe something is taking out the tuner and it took this one out too )

It will give you a little more information anyway.

 

[QuantumCheese]

Blimey, where did you drag this one up from!! this particular 'project' has been languishing in a cupboard for a while now waiting for me to get round to either fixing it or binning it. thanks for the reminder

Do you have a picture of the power supply. No 5V means bad power supply. .

I think you misunderstand my comment of there being "no 5V". What i mean is with reference to the PDF i posted, I have a 32" set. the outputs of the PSU on that model are -
Vp, Vstby and 12vsw. where Vp is 24V and Vstby=3.3

There is indeed 5V, however that is generated by the SSB from the 12V rail.

in the attached picture the psu is the board on the left. two connections leave that board top left and go to the inverters. a 3pin cable exits the top (X220) to power the DVB tuner board. the connector leaving top right and going to the central board named the SSB (X200) and carries the power to the SSB and the control signals back to the PSU. By hard-wiring pin11 i have fired up the backlight to test it comes on. it does.

 

[QuantumCheese]

As a silly suggestion... Last time you removed and replaced the tuner.

. (Or maybe something is taking out the tuner and it took this one out too )

Not a silly suggestion! I'm sure i had done that already, but in the spirit of refreshing my memory i did it again. no joy ;(

And the prospect of the replacement board i bought being somehow cooked by the as yet undiagnosed fault is a worryingly real possibility me thinks. this set may be for the scrap after all

 

[(*steve*)]

I would think that the most likely cause of it taking out other boards (if this is actually what is happening) is overvoltage (or perhaps overvoltage transients).

Measure the supply voltage at the board (or even at the chips) and confirm they are within range. Perhaps take a look on a scope to make sure they're not very noisy, or have spikes, excessive ripple, etc.

 

[QuantumCheese]

Going by the notes i made, I've traced my way around the IC called 'Hercules' on the SSB, checking the various small supplies on that board and they all appear correct. I don't think i scope'd them I probably just used my DVM.

Considering that their are essentially 3 boards in this set. PSU, SSB and DVB. I worked on the assumption that as DVB was an option on the set i could unplug it.
this left PSU & SSB. the PSU appears to measure OK, so i took a stab on it being the SSB board, hence i found another. I suppose it's just possible that the replacement SSB i bought has exactly the same fault as the one i have already - which would be irritating! either that or
a) the PSU isn't coming up cleanly and/or i missed something there or
b) i bought a duff SSB and it's probably time to concede defeat, the price of new 32" tv's now is depressingly cheap and it was my intention to fix this & use it so i'd best chuck it & stop wasting my time on it!

 

[QuantumCheese]

Well, i give up. I disconnected the PSU entirely and powered it up using bench supplies.
with the dvb board unplugged i got a led blink error that could be interpreted as 17 which equates to i2c error comms dvb board - which makes sense, it was unplugged
with the dvb board connected & powered I get....... ta daa exactly the same conditions as when it's powered by it's own supply. Nuts!

I've checked all the supplies generated on the dvb board, and found and checked the elusive POR device. all look good.

So this one's for the skip. I think i've done everything and more in my power to keep it out of land-fill, but it's number's up.