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Discussion Starter · #1 ·
Hi Folks,


I have a 6.5 year old Hitachi plasma that works fine for a few minutes and then blanks out (goes black). Powering off/on fixes the problem for a while, then it happens again.


The TV repair guy said I needed a "PWB Assembly Signal Board" and it would cost $921 for the part.


Not knowing what this board does... Does this sound right? Obviously, at that cost, the fix price is not worth it, however I really hate to throw stuff away.


Any advice would be appreciated.


Thanks

-Hal
 

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There are specialty parts shops that sell guaranteed used boards, removed from working plasma sets, for much less. Do an ebay or google search for "Hitachi Plasma boards". The "Input" boards typically go for $99 to $150. The boards are easy to replace, if you are brave enough to do it yourself.
 

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Discussion Starter · #3 ·
Thanks. I am all for a DIY approach. I wish I understood what this part was for of if it is part of a larger assembly. Can anyone enlighten me on what an "Assembly Signal Board" does? The set is a Hitachi CMP4120HDU. The part number is supposedly JP04502, however I don't find many matches to this item.


Thanks Again,

-Hal
 

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Since I am involved in that kind of work, I am going to speculate that the part that is bad is a Signal Input board. It is probably written backwards since they are often written from highest level item down. Assembly usually means "collection of parts to make up a higher level item". The PWB means printed wiring board (same as printed circuit board -- often, though not strictly correct -- referred to as circuit board.


So basically the signal input board is bad. On the board itself is a part or an assembly number which will definately be the one you want* Also, searching just the part number sometimes helps since often these boards are sold as OEM parts to other manufacturers.


* Sometimes the boards are revved and have been superceded by another part number.
 

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Discussion Starter · #5 ·
Thanks for the reply. I certainly appreciate it.


I went and talked to technician today and got a little frustrated, probably because I don't understand how Plama's work. The part number I was given (JP04502) does not really turn up many matches on google. I went to a site and paid to download a service manual for this set (Hitachi CMP4120HDU) and it does not list this part number. But, I think that maybe I have solved the riddle.


I have taken off the back of the unit and I can't find this part number on any of the boards. But, from reading the service manual, it appears that there are two boards to which this my be referring. One is the "video board" that contains the component video, composite video inputs and s-video inputs. This board appears to connect to a board called the "Signal Board" (sounds familiar) which contains the RGB inputs (BNC & D-Sub). This board connects to the panel module board.


So, I would guess that even though I was using component video, it is probably the "Signal" board with the RGB connector on it which is bad. As an experiment, I am going to setup the monitor connected to a PC and see if this the picture blanks out again.


Does this sound logical?


Thanks much!

-Hal
 

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sounds quite logical. Though not a guarantee, you are taking the video out of the equation. If it works with the computer then you're probably safe assuming it is the video board. Enter the TV model number and some of the words that the manual refers to in google and see if you turn up anything else.
 

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Quote:
Originally Posted by nobail /forum/post/12982975


Does this sound logical?

Absolutely, that is what I would do. In fact, while you are at it, make sure that if the PC input works, that the component video is still broken. If possible, remove it and reseat any connectors, check for excessive dust, etc.


In practice, if I have performed a proper root-cause analysis, then when I fix it, I should be able to break it again. That is a confirmation step that I like to see performed in general.
 

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Discussion Starter · #8 ·
Thanks for the replies. I gave it a shot with the PC input and the same problem happens. So, now I am off to find a signal board.


- Hal
 
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