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Discussion Starter · #1 ·
Hi all!

Great board! Hello to all!

I have a ws 55809 with convergence problems. The TV was purchased new (way back before cable provided HD service) and has never been serviced.

Skipping ahead, I decided to order a 'kit' (6 3.9 ohm 2 watt resistors, 2 stk 392-570 chips, and 2 125v5a pico fuses) from a company online. They assured me that these were OEM chips. Thinking I could save time, (don't have to source the parts, pay seperate shipping etc etc) the price seemed fair so i gave it a shot...

On to my question..If only one chip were bad, is it possible that both fuses (F9A04, F9A05) would blow? :scratch:

Thanks in advance!
 

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I recommend reading the convergence repair sticky very carefully for the first ten posts. I also recommend having the service manual BEFORE attempting any repairs. If you had that information it would be clear from the schematic that the fuses supply both chips and either chip could potentially blow both fuses. I also recommend clearly in the sticky to only use known reputable suppliers because of the frequency of getting bad parts. Unknown vendors can claim anything they want, and even some of the most reputable have been burned by what they think are first quality OEM parts.
 

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Discussion Starter · #3 ·
Thanks for your quick answer. Also, thanks for all the help you provide to this forum. I read quite abit before posting, so again thanks!
 

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It looks like you have the same TV I'm currently working on.
F9A04 & F9A05 are for the 24V supply, both chips share the same power source, and share the same fuses, so it does'nt matter what chip goes bad, it will blow the fuses.

I read some where that the Mitz use one chip for vertical and the other for Horizontal, and that the chip used for Vertical will fail first because of the high frequency/more heat. But I could be wrong.
 

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Discussion Starter · #5 ·
It's fixed now. Supplier sent a bad chip to start with...If there were 1 in 10000 i would get it!! Did take a lot of head scratchin' and fuse replacein' to find the problem though. In hindsight i probably could've just re-soldered the old chips to begin with and everything would've been fine..

:dumbcrazy:
 

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Who is your supplier? Please be specific so that others can benefit from your experience. What makes you sure that you got a bad chip? It is much more common to damage them when installing them by missing an open connection, an open fuse, bridging a connection, or failing to discharge power supply caps.
 

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Discussion Starter · #7 ·
The vendor is tvrepairkits (with the usual . suffix added) and I would give them a big thumbs up! In the beginning i replaced the two STK's and put the board back in. Fuses blew in about 3-4 secs. I then removed the chips and replaced the fuses. With no chips the TV came back up. The company then sent me another chip and some more fuses. Put in new chip - TV's ok. Put in one of the 'old-new' chips - 2 more blown fuses. Replaced fuses, put in other 'old-new' chip and Voila! Works like a dream, didn't even have to adjust the convergence. I attribute this to having tried 'factory reset' before I accepted the fact that something was going to have to be done...

I have done plenty of electronics work in the past, including building prototype boards from a blank and a build list. Surface mount included - so I'm about 99.9% sure that i didn't bridge a connection..

The replacement parts we sent to me free of charge...
 

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I had good luck with TVrepairkits in the past.
IIRC the chip's were still in there original "SONY/Sanyo" box.
Sure was'nt a china knock off.
 

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Did you discharge the power supply caps for the + & - supplies to the chips? These sets often hold some charge and you can easily blow a chip if you don't.

I have heard of no prolbems with them as a supplier, and if they are still buying parts from the vendor that they were at one time, it is unlikely that you got a bad part, though it is alway a possibility. Even experienced techs blow a part every now and then...I did so just a couple of weeks ago. The rate of returns is extremely low for the vendors that I use, and they are almost all to consumers, as opposed to pros. Most professionals know when they damaged a chip, while most DIYers do not realize all the ways that it can happen.
 
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