Toshiba 32BV500B fault - Vestel 17PW26-4

[orbiter]

Hi guys just got a Toshiba 32BV500B to repair. It has a Vestel 17PW26-4 PSU.. The initial fault was that it wouldn't turn on at all, no standby LED or anything..

So I did some tests firstly checking the PCB fuse which was blown, then I checked every capacitor (out of circuit) and found all except C874 to be within spec and have good ESR.. I replaced both the fuse (with temporary 3A one) along with C874. However there was still nothing on power up.

So.. Did some more tests and found D893 failed along with transistors Q813 & Q814.. So I went ahead and replaced those too.. On plugging-in the tv it then fired up and the screen came on for about 30 seconds.. Then both the replaced transistors exploded again with the source leg being blown off both.. At the same time the pcb fuse and D893 had failed again

So I guess I've got a short here when something switches after about 30 seconds after power-on.. I've not yet replaced IC830 (FAN7711)

Here is the PCB and replaced components in red...

Anyone got any advice please?

[vinceroger69]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

this is whats in the repair kit for this fault so best replace all parts

F800
Q813
Q814
IC830
D894
R860
R8661
R971
C840

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Wow.. Great response speed there Vince, thanks very much indeed. I've got all those bits so I'll get on it.

Thanks again

[diif]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Maybe D882 and D883 also.

[vinceroger69]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

There are repair kits online but usually better to source the parts yourself as cheaper its a pity they dont give the values of the resistors etc but should be on the schematic or printed on the smd parts.

Edit as diff says maybe best to change D882 and D883 as well as we have saw these failed in other threads on here

[dick_barton]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

D893 feed capacitors C931, C961 & C962 and which are across the 24V supply. I would check that you do not have a short circuit across the 24V supply. You can measure across any of the above capacitors.
If you do have a short circuit or low ohms that would account for the mosfets blowing as well. If D881 fitted then check that diode too.

Also as suggested above check D891, D892, R860, R861, R864 and R865. If any of those are damaged then change the FAN IC

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

@diif.. Ok I'll check those. Thank you.

@vince.. Ok thank you, I think I have all the parts in my stock, and also an app for when I get stuck with my resistor values

@dick barton... Ok I'll check those too.. Thank you.

Thanks all

[diif]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

I have a 17PW26-4 here, I don't know if it works or not but I can measure any values you might need if it helps.

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

I have a 17PW26-4 here, I don't know if it works or not but I can measure any values you might need if it helps.

I appreciate that diif thanks.. I'll get back to you if necessary.. Up to now though I've found that the two 33ohm smd resistors R860 & 861 are reading way off.. in the Mohm range actually so I'll swap those after my tea and check the rest of the stuff too. I'll let ya know how I get on.

Thanks again.

[dick_barton]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

I would change the FAN7711 as a precaution.

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Hi again fellas...

Just an update... So I've got the power supply going to a certain extent BUT the LED on the front of the tv is flashing constantly I've tried holding the touch sense power button for 20 secs etc and leaving the tv alone for a while in the hope that it would reset, but the LED still just flashes away.. No fault CODE flashing.. Just continuous flashing.

I've started checking voltages at PL816 which is the socket off to the main pcb (schematic below) and a couple of voltages are missing there.. I do have the following though.
+3.3v standby (pin 16)
+5v standby (pin 14)

But no +12v or 24v (pin 12)

The only real thing I can't check fully is the Fairchild IC (FS DL321.) which is a PWM controller, this has 20v on it's ground pin :o .. Now I'm hoping that this is an internal short.. So I've ordered a couple of those from eBay and they should be here today or Monday

BTW.. The main board is a (17MB45M-3)

17PW26-4 Schematic... https://www.mediafire.com/?c1rn8stprfp791x

[dick_barton]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Disconnect the main board and on the power supply connect a 1K resistor from +5V standby to Stby (pin 6) and then check 12/24V

[vinceroger69]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

This pdf has some good information regarding the psu etc

[dick_barton]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

This pdf has some good information regarding the psu etc

Interesting. Thanks

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Hi guys,

Sorry for not responding sooner, for some reason I did't get notification that there were any replies
even though I am subbed to the thread and instant notifications are set to ON.

Anyway.. I've reaplced DL321 and there's no change anywhere.

@dickbarton.. I've just tried whast you suggested but there still no 12/24v

@vince.. Thanks for that .pdf it's very helpful.

pin 4 =8v
pin 6 =2.5
pin 13 =0.14v
pin 14 =5v
pin 15 = 3.3v
pin 16 =3.3
pin 15/17/19/21 =0.2v
pin 18/20/22 =0.4v
pin 25 = 0.14v
pin 26/28 =0.14v

Is there a way that these PSU's can be powered without the mainboard connected guys?

Thank you

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

As it's not possible to edit posts here guys?.. I just needed to say that the voltages in my previous post are with the tv turned on (with stby light continually flashing)

I could do with some more advice please guys if you have some..

Is the PSU supposed to show the correct voltage at its output without having the mainboard connected guys?

Thank you

[dick_barton]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

What was the original part number for D893 and what have you put in its place. Was the original an UF5404?
There's also a reference in another post relating to these power supplies to a 0 ohm smd link on the underside of the board that can go open circuit so you lose your 12/24V supply.

https://www.badcaps.net/forum/showth...light=17PW26-4

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

What was the original part number for D893 and what have you put in its place. Was the original an UF5404?
There's also a reference in another post relating to these power supplies to a 0 ohm smd link on the underside of the board that can go open circuit so you lose your 12/24V supply.

https://www.badcaps.net/forum/showth...light=17PW26-4

Ahh... Perhaps wrong diode.. The original diode was a UF5402... I fitted a 1N5408 (1000v)

[orbiter]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Looking at the diodes specs though a 1N5408 should be fine?

[vinceroger69]

Re: Toshiba 32BV500B fault - Vestel 17PW26-4

Looking at the diodes specs though a 1N5408 should be fine?

uf 5402 is a ultra fast diode im not sure about the in 5408 i think thats just a general purpose one?