Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

[richhol]

Goodmans GTVL32W26HDF (32" approx 2007)
Vestel MB22 chassis
PSU 17PW15-9

I had this TV for repair from a family member a few years ago with a no picture fault. It seemed OK otherwise and sound was present. I changed a few bulging capacitors on the PSU board with no fix and it turned out to be a blown SMD fuse on the TCON board (CP101). It has arrived some years later with the same fault, so off I went to the same place, but the two TCON SMD fuses (CP101/CP228) are OK.

Looking more carefully there is no backlight but the picture is there. There does not appear to be any brief backlight flash at switch on so I'm fairly sure there is no backlight at any time. Tuning, sound and standby operation are all normal.

- I've changed more caps that have bulged since last time (C851, C812, C818)
- The 24V rail is steady at 24.6V when on and present on the inverter board
- BL_ON/OFF on PL802 pin 12 : 0V standby and 3.3V TV on and present on the inverter board
- A_DIM on PL802 pin 11 : 0V standby and 2.3V TV on
- A/D_DIM_SEL on PL802 pin 9 : No connection
- D_DIM on PL802 pin 10 : No connection
- The big cap (C819) has 345V in standby and 390V TV on, which I have read is correct
- C877 + C878 get mentioned a lot but I have not changed (yet) - they measure as 15n1 and 14n6 out of circuit

The panel is a Samsung LTA320WT-L16 with SS1320WA16 inverted board

- Nothing appears burnt on inverter board. Slight irregular heat (?) ticking when TV on - may be normal
- Two SMD fuses (5A/35V) on inverter board intact. 24.6V present.
- Two Samsung electrolytic caps on inverter board look OK
- Transformer LT-3224 (x4) have 1K5 secondary resistance, all the same
- Transformer primaries all have same voltages when TV on, not sure of pin-out
- Nothing appears burnt at the CCFL sockets (have had the panel apart)

Any further pointers would be appreciated - thanks.

Rich

[dick_barton]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

You have the PFC voltage (390V) so it looks like the power supply is fine.
I suspect a tube or inverter fault.
Measure all the inverter transformers both primary and secondary resistance (set off) and give the results.

[dick_barton]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

You have the PFC voltage (390V), sound and picture so it looks like the power supply is fine.
I suspect a CCFL tube or most likely a faulty inverter.

Measure the resistance of all the inverter transformers, both primary and secondary (set off) and submit the results.

[budm]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

"There does not appear to be any brief backlight flash at switch on"
I would say you have bad inverter board, if you have bad lamp/s the inverter should still fire the startup Voltage first (you will see the lamps flash on) and then goes into shutdown if bad lamp/s is detected but you are not seeing that.
It is SAMSUNG Inverter board which is known for being bad, reece fixed some of these with bad PWM IC.
Samsung SSI320WA16 Backlight Inverter

[richhol]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

See new picture for pins.

All measurements taken with transformers in circuit.

(P1+P4 don't appear to be connected - mounting only??)
P2-P3 : 0R dead short on all 4 transformers

S1-S2 : 1K45 on all 4 transformers except top transformer=1K51
S3-S4 : 1K45 on all 4 transformers except top transformer=1K51

The additional small transformer shown in original picture Inverter-1 has primary of 30R and secondary of 32R, again mounted in circuit.

Thanks for your help.

[CapLeaker]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Since the backlight doesn't even flash for a second, I actually doubt it would be one of the transformers or one of the CCFL's going bad. That being said, I'd still like to see the secondary's on each inverter transformer. That should still try to power up.
Maybe check around the DC-AC inverter control IC? Some inverter control IC's you can disable the protection. I do not recommend doing that.

Probably cheaper and less headache to just get another inverter board. Unless you can't find one... I guess then you have to repair that one. Got to go.

[dick_barton]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

If it is the inverter board then there's one here at a good price.

http://www.lcd-plasma-parts.co.uk/ss...msung-inverter

[vinceroger69]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

http://www.lcd-plasma-parts.co.uk/ss...msung-inverter
not sure what there postage costs are?
but they also have them listed on ebay
http://www.ebay.co.uk/itm/SSI320WA16...4AAOSw-FZXjyR4

Edit! dick barton beat me too it

[ReeceyBurger123]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Common issue on this board is failed controller. Had this before.

[ReeceyBurger123]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Also there is two caps on the Psu I urge you to replace, two 100uf 50v caps next to the top heatsink replace them as they commonly fail which will cause issues in that supply.

[richhol]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

> ReeceyBurger123

A few more observations. Another thread refers to a very similar Samsung inverter board:
www.badcaps.net/forum/showthread.php?t=11182
Controller chip BD9882 seems hard to find in the UK but can be had for USD1.46 at Aliexpress [with a 4 week+ wait!].
I measured a few voltages on my BD9882:

Pin 11 (standby): 2.2V (if over 1.8V backlight should be on,so correct)
Pin 13 (regulator out): 3.1V (same as in other thread)
Pin 12 (under/over voltage): 1.54V (OK I think)
Pin 20 (Vcc): 4.5V (low?? Datasheet shows 5-14V range,other thread=9.1V)

The low Vcc could be an issue or faulty BD9882 dragging it down? It is hard to be sure, but I think the Vcc trace goes to a GY644 (the marking has not shown up at all on the picture attached). I cannot find out anything about GY644 but maybe a regulator.

Your comment on the two 100uF/50V caps noted for later (C834/C835), but I don't think you were meaning this to be a possible cause to the no backlight fault? These appear to be labelled 33uF/50V on my circuit diagram but are 100uF on the board, as you rightly say.


> dick_barton
By pure chance these guys http://www.lcd-plasma-parts.co.uk/ are only 8 miles from me so that board is a possibility.

> budm + CapLeaker
Just to be sure I've powered up the TV from standby in complete darkness and there is definitely no initial backlight flash.

Thanks to all.

Rich

[CapLeaker]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

That control IC is bad or there is an issue around it.

[ReeceyBurger123]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

That control IC is bad or there is an issue around it.

+1 as suspected, check for short circuit devices in that area. Also the caps are not an issue atm but I advise you replace them after the inverter repair.

[richhol]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Final info on this...

I cut the trace to pin 20 (Vcc) of the control IC leaving that pin isolated (see X on new pic). The voltage on the feed (left of X) then jumped up to just over 9V which is almost the 9.1V in the other thread I mentioned earlier.

Zener ZD8 is marked F4 which is also 9.1V so this is likely to be the correct supply voltage for the IC. The larger item below the Zener that I previously suggested was a regulator has a 'Q' board reference so more likely a transistor.

I'll decide whether to go with an IC or a board in the next day or two, though I suspect I don't have the eyesight and equipment to change the IC or the patience to wait for one to arrive!

Thanks again - will report back with final status, whenever that may be.

Rich

[ReeceyBurger123]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Keep us updated buddy

[richhol]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

A used eBay inverter board arrived this morning, fitted and the TV is back to normal with backlight. I'll hang on to it for a day or two to check it behaves.

The two extra caps (C834/C835) mentioned by ReeceyBurger123 also changed (happened to have some Panasonic of the correct value on hand - this almost never happens!). I also changed the two smaller ones below (C826/C840) since I also had them.

Interesting that this TV has been fairly reliable for a Vestel, but the two repairs have been to the Samsung TCON and Inverter boards and not the PSU. Some preventative cap changing was done at the first fault time and some more now. Details of caps changed this time, though don't take these as gospel from my cheap-o Chinese component tester:

10uF/63V G-Luxon ESR 12R Reading 9uF
33uF/50V CapXon ESR 7R9 Reading 32uF

100uF/50V G-Luxon ESR 2R7 Reading 90uF
100uF/50V G-Luxon ESR 1R1 Reading 92uF

1000uF/16V G-Luxon ESR 6R8 Reading 155uF (bulging)
1000uF/16V G-Luxon ESR not detected Reading 28pF! (bulging)

The last two are obviously shot, but those ESRs on the top two look very high to my untrained eye.

Thanks again.

Rich

[dick_barton]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

So another set saved from the scrap heap.

[ReeceyBurger123]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Awesome work Also these older Vestels are a poor design but hey I know some that have been working for over 10 years-my nans Tv which is a 17pw20 (same as PW15) has been working since 2006 not a signle issue these ones last better than Samsung's and Lgs do. Hopefully you get many more years of service from it......hopefully

[CapLeaker]

Re: Vestel MB22+17PW15-9 (Goodmans GTVL32W26HDF)

Good to hear!