Sanyo (Vestel) CE26HW03 with 17PW15-8

[Trevtron]

A friend has given me this old set to have a look at. It is old, but owner would like it fixed if poss, so I said I'd give it a try.
It has the 17PW15-8 power supply and the main board is a 17MB15E-7. It doesn't look like anyone has had the back off before.

It appears to be stuck in standby, the blue standby LED stays lit.

First thing I did was replace the two cap's 877 & 878 but still the same. Can't see any bulging electrolytics, it doesn't look like the set has had much use in fact, it's all very clean.
I checked the voltage on the 24V rail to the inverter and it does increase somewhat when trying to start up the set but it trips and returns to 0V after about 1s. Same with the 5V rail. C819 sits at 325V in standby, rises to about 390V when attempting to start then returns to 325V.
As the set's not worth much I thought I'd ask if anyone has had the same fault, or could suggest things to check rather than waste much time on a possibly fruitless mission.
Any help greatly appreciated.

TIA.

[dick_barton]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

I would still suspect a bad electrolytic capacitor on the power supply. Can you unsolder them and check them all out.

[jetadm123]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

There's a repair kit on eBay for your board. I suggest you check the parts identified in the listing against the parts on your power supply.

http://www.ebay.com/itm/17pw20v1-v2-...SSPklm6tsI9k9w

[Trevtron]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

Thanks for the prompt responses guys.
There are 25 elco's on the board (roughly), I've checked the obvious ones (those mentioned in the repair kits and the ones sited horribly close to heatsinks etc.) with an ESR meter and all checked out OK.
I did have a previous experience with a 32" version of the same model where the audio o/p IC had shorted and gave similar symptoms IIRC, the give-away was a loud thump from one of the speakers on start-up.
Therefore I am not 100% convinced it is in fact a PSU issue- thinking perhaps it is tripping due to excessive current being drawn by something else.

[vinceroger69]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

can you disconnect the mainboard and force on the psu and check all output voltages

[petehall347]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

see if the audio chip and the cap next to it are getting hot . and also check the speaker out voltages . they should be 0v ish .
mind you saying that it may well be dropping the power to audio so will be a waste of time .. just done a more newer Philips that kept the audio power on when everything else had shut down .. it also burned a speaker out . one was really hot after a short time .

[Trevtron]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

can you disconnect the mainboard and force on the psu and check all output voltages

Yep, happy to do this. Do you know which pin forces it on?

see if the audio chip and the cap next to it are getting hot . and also check the speaker out voltages . they should be 0v ish .
mind you saying that it may well be dropping the power to audio so will be a waste of time .. just done a more newer Philips that kept the audio power on when everything else had shut down .. it also burned a speaker out . one was really hot after a short time .

The set won't run long enough for anything to get hot. I disconnected the audio amp (it's a separate board) still the same.

[vinceroger69]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

if you can post a clear picture of the connectors on the psu and any writing by them we should be able to advise you then im sure reece will have a idea on what to check on the psu and also if you need to force on the psu on these sets to test all voltages as its vestel im never 100% sure but im sure reece will advise.

[Trevtron]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

if you can post a clear picture of the connectors on the psu and any writing by them we should be able to advise you then im sure reece will have a idea on what to check on the psu and also if you need to force on the psu on these sets to test all voltages as its vestel im never 100% sure but im sure reece will advise.

Thanks mate, here is another of the front edge of the board showing (most of) the socket numbers.

NB The vertically orientated socket (next to the 2k2) resistor was vacant.

[vinceroger69]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

schematic

[Trevtron]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

Thank you for the circuit vinceroger69.
Pin 6 on PL803 is labelled ST_BY (on the diagram) and on the set this pin is at 3.1V. When I try to start the set, it drops to 0V but goes back up to 3.1 after about 1s. (When it's trying to start up I can hear a faint buzz/hiss from around the big inductor near the mains input).
I see there are several other references to ST_BY on the circuit but it's not clear to me what they mean.
I am worried about forcing this pin 6 down to 0V in case it damages something else. Been there lol!

[vinceroger69]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

im not sure myself too be honest hopefully a more experienced member will comment and know if these sets need to be/can be forced on to check all the voltages and what pins etc

[jetadm123]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

The schematic shows at least 2 surface mount fuses, (F803 and I can't read the other). I would at least check those before going any further.

[Agent24]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

Good idea to check fuses. I can't figure out anything on that schematic at the moment, it's an awful shambles. I'll try to figure it out later if nobody else does first.

There is a BL_ON/OFF pin on a connector somewhere, but good luck finding out where it goes to on the schematic.

[Agent24]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

Thank you for the circuit vinceroger69.
Pin 6 on PL803 is labelled ST_BY (on the diagram) and on the set this pin is at 3.1V. When I try to start the set, it drops to 0V but goes back up to 3.1 after about 1s. (When it's trying to start up I can hear a faint buzz/hiss from around the big inductor near the mains input).
I see there are several other references to ST_BY on the circuit but it's not clear to me what they mean.
I am worried about forcing this pin 6 down to 0V in case it damages something else. Been there lol!

ST_BY Pin 6 on PL803 is an input to the PSU, powered from the +3.3VSTBY rail. This will be pulled to ground by the mainboard (you see it go to 0v when this happens) and the power supply will try to come out of standby and up into full operation mode. So that's the PSU main power enable pin.

You could pull this low with a 1K resistor to manually start the PSU. Then you can check all the other voltage rails and see if they come up correctly without the mainboard connected, as vinceroger69 suggested.



Pulling ST_BY Pin 6 LOW turns on the IC811 Optoisolator, and switches IC828 (an LM317) which would appear to supply the Feedback voltage VF_MAIN from IC806, a TNY266 to IC802.

This is where things don't make sense. I'd expect that IC802 is a PFC controller, but it's listed as an IRF7314 which is a dual-MOSFET. I think this may be a mistake. It would be interesting to see what is actually written on your IC802.

The actual PFC MOSFET seems to be Q803.

But since C819's voltage rises to 390V as you say when the PSU tries to come on, it sounds like the PFC is working OK anyway.



Attached datasheets for future use

[Trevtron]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

OK, a bit of progress- but it's still dead.
First off- it's definitely the PSU that's faulty, I 'borrowed' one off another set & everything works as it should. Unfortunately I had to give it back!
So, original board back in. With only the mains plug on, there was no voltage on any pin on PL803. But with plugs 803 & 806 in, the 3V3 was up on pin 6 of 803. But pulling it down to 0V with a 1k2 resistor didn't do anything besides giving a slight buzz/hiss from the top RH corner. Even C819 remained steady at 325V.

To answer Agent24, here is IC802.

[Agent24]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

I can't see what the last digit is properly, but it's very likely either an L6561 or L6562 PFC controller, which makes sense. Certainly NOT a dual-MOSFET as the schematic says

I am not sure why you don't get standby voltage without the mainboard connected. Does the working PSU have the same behaviour?

The buzz\hiss from top right of PSU sounds like the PFC transformer running when the PSU is told to start up.

[petehall347]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

L6568d

[dick_barton]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

You say that the voltage across the large capacitor reaches 390V before falling back. So the PFC circuit is starting up but not holding.
I would look at all the small electrolytic capacitors rated at 50V or more and check them out.

[Trevtron]

Re: Sanyo (Vestel) CE26HW03 with 17PW15-8

I can't see what the last digit is properly, but it's very likely either an L6561 or L6562 PFC controller, which makes sense. Certainly NOT a dual-MOSFET as the schematic says

I am not sure why you don't get standby voltage without the mainboard connected. Does the working PSU have the same behaviour?

The buzz\hiss from top right of PSU sounds like the PFC transformer running when the PSU is told to start up.

Good question, the answer is definitely NO! The good supply has lot more life to it, though that pin 6 on PL803 is still low. However it does have 24V on the yellow & black sockets which the dead board doesn't, and also various other live pins where the dead one didn't. In fact the only output from the dead board is 3.4V & 5V on PL806.
So this gives me some homework to do this weekend- or perhaps next week- I'm fed up going to bed with little green tracks in my eyes!

PS IC802 is a L6562 on the 'good' board