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toshiba 32AV500U LCD inverter ?
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Dan the TV man
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PostPosted: Mon Oct 12, 2009 9:59 pm    Post subject: LCD inverter Reply with quote

If you have sound and no picture shine a strong flashlight into the blank screen.If you see a faint picture the inverters are bad.A board can look perfectly fine and still not work.
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bradandjaya



Joined: 12 Oct 2009
Posts: 6

PostPosted: Tue Oct 13, 2009 1:01 am    Post subject: Re: LCD inverter Reply with quote

Dan the TV man wrote:
...If you see a faint picture the inverters are bad.A board can look perfectly fine and still not work.


Dan, what a simple - yet effective - little diagnostic trick! I was so happy to see a dark Wii menu once I plugged the video cable into the side of the set and shined a headlamp into the lcd.

What voltage on what pins should I see coming from the slave (HIU-813-S) and master (HIU-813-M) boards ? I would like to know which one needs to be doctored up - hopefully not both Crying or Very sad

Is Toshiba my best source for the transistor(s)?

Thanks!
Brad
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bradandjaya



Joined: 12 Oct 2009
Posts: 6

PostPosted: Tue Oct 13, 2009 12:39 pm    Post subject: The more I read, the more I learn... Reply with quote

So, the parts that were previously replaced on the master inverter board (and slave now that I look closely) were the 330uF capacitors and the surface mount transformer (not transistor!).

I think I should be able to check for power coming out of the transformer and determine if the transformer is bad or if the backlight bulbs are suspect. I understand that the transformer is changing the 24VDC to something AC, but which legs on the surface mount should I check, and what range of voltage? Is that potentially dangerous, and should I be checking resistance between transformer legs instead? Or should I check the connector that goes from the inverter board to the lcd for high AC voltage?

I'll keep reading and hope for more inspiration from you experts.

Thanks in advance,
Brad
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Dan the TV man
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PostPosted: Tue Oct 13, 2009 5:12 pm    Post subject: LCD inverters Reply with quote

The inverters on this model are over $200 each.You really dont need to be testing these boards live, it can be dangerous.There is a company called PTS Corp-18008447871.You can send them the boards and they will rebuild them,they also have a website.You could also search Ebay Electronics ,you could find this model with a broken screen.They also have used boards sometimes.
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NoMONEYcollegeKID
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PostPosted: Fri Nov 27, 2009 6:50 pm    Post subject: Toshiba32av500u backlight inverter Reply with quote

It appears that I have a common problem with this model of Toshiba product. When the TV is on, green light is present as well as audio, but the picture is absent, (atleast 99%). I'm limited with electronics anything beyond locating/replacing requires a meticulous walk-thru developed an outside souce. Local TV shops seem afraid of the task and question their ability/resources to do so. Toshiba offers a lengthy bureaucratic glimmer of extended warranty. What's one to do? Repair or Replace? Please help.
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bradandjaya



Joined: 12 Oct 2009
Posts: 6

PostPosted: Sun Nov 29, 2009 9:37 pm    Post subject: Some metered values on the Slave Board look bad Reply with quote

I've picked up this project once more. Taking both inverter boards out of the tv, and poking around with a volt meter (checking resistance), here's what I have found:
1. On slave board - F1 appears to be blown as there is infinite resistance. F1 on the master shows zero Ohms.
2. On slave board - two of the transistors (FDD8447L) seem to be shorted as the resistance between the middle/back and both left and right legs is zero. The 330uF capacitor that is closest to these also appears bad, with infinite resistance between it's leads. On the master board, all 4 transistors have similar values (though 1 is pretty different than the other 3) between their centers/backs and left & right leads. Both caps on the master board have zero Ohms between their leads.

Based on the above, it looks like the slave board needs a little repair. Should I look further than the fuse, resistors, and capacitors? Remember, my Toshiba 32AV500U has a diagnosed backlight issue - the LCD panel appears good as I can see a faint image with a video source connected and shining a bright light onto the screen. Sound is fine.

Should I meter the transformers? If so, what values should I expect when measuring resistance between the transformer leads?

Thanks for your continued help and advice...
Brad
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bradandjaya



Joined: 12 Oct 2009
Posts: 6

PostPosted: Mon Nov 30, 2009 2:09 am    Post subject: Re: Some metered values on the Slave Board look bad Reply with quote

bradandjaya wrote:

1. On slave board - F201 appears to be blown as there is infinite resistance. F1 on the master shows zero Ohms.


Each board has one fuse. I corrected the label of the fuse on the slave board.

Any suggestions on next steps?

Thanks,
Brad
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dkollander



Joined: 23 Oct 2009
Posts: 7
Location: United States

PostPosted: Mon Nov 30, 2009 6:28 am    Post subject: 32av500u Reply with quote

I have been doing some research on the 32av500u and here is what I found....apparently on the dual inverter model the 4 transistors FDD8447L and the IC BD9897FS are prone to failing...I am looking for a source for these in the US that I don't have to buy several hundred of them.
If you live in the UK I did find this Site that sells a kit to fix the boards.
http://www.ohmsupplies.co.uk/epages/62027733.sf/en_GB/?ObjectPath=/Shops/62027733/Products/Kit62

Other research has shown me that the single inverter models have the exact same boards (excluding the inverters)in them. The power supplies even have Both inverter connections. I assume they only use the 14 pin connector as that is what is on the single inverter board. So this means that the back light itself must be different. Not he LCD or logic board...just the light part.... Besides the connectors and possible pigtail length.....What I don't know is what the difference is between the 2 back light assemblies..hopefully just the side of set the back lights connectors attach to the inverter.

Some more info thatmay be useful in locating a donor set....The production change over date from the dual to single is sometime in April or May 2008 I figure as I have Feb & March 08 set...both with dual inverters and I found online a May 2008 model that was a single inverter and I am trying to buy his back light and inverter to fix my set if the price is right..
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bradandjaya



Joined: 12 Oct 2009
Posts: 6

PostPosted: Mon Nov 30, 2009 8:15 pm    Post subject: Reply with quote

dkollander wrote:
I have been doing some research on the 32av500u and here is what I found....apparently on the dual inverter model the 4 transistors FDD8447L and the IC BD9897FS are prone to failing...I am looking for a source for these in the US that I don't have to buy several hundred of them.
If you live in the UK I did find this Site that sells a kit to fix the boards.
http://www.ohmsupplies.co.uk/epages/62027733.sf/en_GB/?ObjectPath=/Shops/62027733/Products/Kit62


That looks like a source for the IC, but they are over charging on the transistors which are $0.73 US each (plus shipping) at Mouser (mouser.com). They have the transistors, capacitors, and fuse(s) at a reasonable (to me) price: about $16 US shipping included gets me enough to repair 4 boards. Unfortunately, the BD9897FS IC (a DC to AC switching converter) has a minimum order of 1,570 pieces at $2.17 each (plus shipping).

Mouser #: 512-FDD8447L
Mfr. #: FDD8447L
Desc.: MOSFETs 40V N-Ch PowerTrench MOSFET

Mouser #: 667-ECA-1VM331
Mfr. #: ECA-1VM331
Desc.: Aluminum Electrolytic Capacitors - Leaded 330uF 35V

Mouser #: 504-TR2/6125FF5-R
Mfr. #: TR2/6125FF5-R
Desc.: Fuses SMD BRICK 5A

Rich-Tech has the IC for $14 plus shipping, better than the Ohm Supplies price:
http://www.richtechparts.com/search.html?sfield=&search=BD9897FS

Any thoughts on testing the IC? Should I replace the caps, transistors, and fuse first to see if that fixes it?

Brad
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dkollander



Joined: 23 Oct 2009
Posts: 7
Location: United States

PostPosted: Tue Dec 01, 2009 5:36 am    Post subject: Reply with quote

I would try replacing the caps, fuse and all 4 transistors (they are cheap enough)...if that doesn't fix it then chip it.

I am still working on getting a single inverter and converting mine...the person that has it threw out the back light assembly so I can replace them as a set. Sad

My other option that would cost me little to nothing is fit up a back light/inverter/power supply from another 32" set I have.

Let me know if you have any luck replacing the parts as I now have 2 sets of inverter boards for the 32av500u.
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