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Help me read a block diagram and fix my TV

Anonymous Mon 29 Apr 2024 10:28:07 No.1459141 View View Reply Original Report

Quoted By:

Hello /wsr/, I have a broken old rear-projection TV lying in my room. These old TVs work by, as the name says, projecting an image through a set of LCD lenses and mirrors with the help of a bright lamp. My TV has a set of safety switches around the lamp plug, but one of these micro switches is physically broken so the TV refuses to turn on as the mainboard detects it as 'not in place'. the led indicator sequence matches that error. I looked up the service manual and came up with this
https://www.manualslib.com/manual/855317/Sony-Kdf-E42a10.html

Anonymous

View Same Google ImgOps iqdb SauceNAO blocks.png, 1MiB, 3300x2200

Anonymous Mon 29 Apr 2024 10:31:38 No.1459142 Report

Quoted By: >>1459162 >>1460204

Mine is the 42 inch vers btw

By the looks of it, taking it apart to get to the broken switch is going to be a pain in the ass (plus I can't find nor think it's a good idea to spend $50 or whatever I'd get charged for a 20 year old part if I can even find it in first place) so I thought if it's just a simple switch maybe I can bridge/short some cables to make the TV think it's closed, shouldn't be hard. I don't know much about electronics, but I understand that from reading Image A (pdf page 15) that the switch in "T2 board" (the broken one) needs to be closed so it can register as 'lamp_cover_closed' or something like that. On Image B (pdf page 36), you can see on the T2 diagram that it goes (I assume that's what it means) to CN8403, I imagine that's a connector full of cables on another board. On Image C (pdf page 39) you can see a more complete diagram but that really eludes me because I'm dumb, there's the T2 block on the top left, and another block with a red arrow next to it. I think that it is possible to grab the first 2 pins on that connector (the ones labeled LAMP_POS and GND), grab the 2 cables that come from there, cut them and short them and that'd complete the circuit? Or am I missing something else here?

There's another diagram on Image D (pdf page 176) but I don't know what that means. And lastly on Image E (page 179) there's what I think is the main board, labeled with name of connectors. I put a red arrow next to what I think I should look for. This board is right behind the back plastic cover so I wouldn't need to take it all apart to get there. I can just get a metal clip and short the last 2 pins right?

I just need someone that actually knows electronics to confirm what I'm going to do will work or if I need to do something else. Thanks for your help.

Anonymous

Anonymous Mon 29 Apr 2024 11:33:04 No.1459149 Report

Quoted By: >>1459152

>4 fans
How loud are they?

Anonymous

Anonymous Mon 29 Apr 2024 11:35:39 No.1459152 Report

Quoted By:

>>1459149
Very, almost as loud as one of those old first generation xbox 360s that sound like a plane about to take off.

Anonymous

Anonymous Mon 29 Apr 2024 13:37:03 No.1459162 Report

Quoted By: >>1459708

>>1459142
Your thoughts seem right. It's funny, the thing that stands out to me the most here is that they fucked up diagram B by labelling lamp_pos as lamp_cov like in T1. If you just short lamp_pos to the neighboring ground pin as shown in diagram E, you're good, assuming the actual issue is the T2 board switch.

Anonymous

Anonymous Wed 01 May 2024 18:45:40 No.1459708 Report

Quoted By:

>>1459162
Thank's for your input anon. One more bump

Anonymous

Anonymous Sat 04 May 2024 00:19:12 No.1460204 Report

Quoted By: >>1460534

>>1459142
If the switch on the T2 board needs to be closed, you can bridge the connection. If there's a connector that goes to the T2 board, you can either: connect 1 LAMP POS (erroneously also referred to as LAMP COV) to 3 GND by sticking a piece of wire in the connector end, or splice those wires together. If you can't do those you can bridge 1 LAMP POS to 2 GND on CN8403 TO QM with a wire. If you can't do any of those because there's no discrete connectors or wires, you can solder a wire between the contacts on the printed circuit board. If there aren't contacts then expose the wires by scraping.

BUT if the switch needs to be open you can just disconnect or remove the T2 board.
However, if the tv does any self checks involving the T2 board (like if it cycles the switch to make sure it's working) your only recourse is to replace the switch with a similar one.
And when you use a wire to bridge a connection, it generally needs to be at least as big as the wires it is connecting. In reality it just needs to be as conductive, of which material and the smallest cross sectional area are the main factors.

Anonymous

View Same Google ImgOps iqdb SauceNAO 547add9900d0f_347510b.jpg, 91KiB, 1500x843

Anonymous Sun 05 May 2024 10:55:54 No.1460534 Report

Quoted By:

>>1460204
Thanks for replying anon, yeah I'll probably do
>bridge 1 LAMP POS to 2 GND on CN8403 TO QM with a wire.
If it's not too crammed in there, and not too small for my old soldering iron. I just realized there's a "P" square thingy to the right of T2 in Diagram C. No idea what that could be, it makes no mention of it anywhere else, maybe a fuse? Protection? But then it'd run through the cables that go over there, unlikely. Found a pic of the T2 board, looks pretty simple there. 3 input pins, 3 switch pins, the ones in the middle saying NC which probably means Not Connected and not Normally Closed... I'll take it apart tomorrow and hope it works!

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